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Select this Article		State and Parameter Estimation with a Sequential Importance Resampling (SIR) Particle Filter in a Three Dimensional Groundwater Pollutant Transport Model Shoou‐Yuh Chang, M. ASCE, Tushar Chowhan, and Sikdar Latif Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000584 Posted ahead of print 30 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Mathematical modeling of the contaminants in the subsurface is important to predict the spread of the plume as well as for risk assessment. A three dimensional subsurface contaminant transport model, with an instantaneous input, is developed to represent the high dimensionality of the real field. Due to the inherent randomness, heterogeneity of the transport process, macrodispersion, non‐fickian motion, and ergodicity, general assumptions of linearity and Gaussian distribution do not hold for the real field. Therefore, a state‐space transport model for the non‐linear and non‐Gaussian system is proposed in this study. In this paper, the state variable (concentration vector) and parameter (first‐order decay) are updated with the simulated measurements. A particle filter, which is a sequential Monte Carlo method, provides a rigorous general framework for dynamic state estimation problems in the Bayesian scheme. In this paper, the reactive contaminant transport in subsurface is treated as a dynamic state and parameter estimation problem. A type of particle filter, commonly called Sequential Importance Resampling (SIR) is used for this subsurface transport problem. The model estimation is compared with a true random field, which acts as a reference. A promising improvement of the estimation accuracy is attained with the SIR particle filter when compared with a traditional deterministic approach. The particle filter data assimilation scheme reduces the prediction error by 48% in estimation accuracy. A standard technique to perform parameter estimation consists of extending the state with the parameter to transform the problem into a suboptimal filtering problem. This approach requires the use of special particle filtering techniques which are affected by several drawbacks. We consider here an alternative approach in combining parameter estimation with the particle filter method. The concept of the norm has been introduced in order to address the sequential weight assignment to the parameter estimation. The estimates of the parameter clearly show the efficacy of this innovative approach in this field.

Select this Article		MBR Process Modeling and Optimization: Case Study of Ulu Pandan Water Reclamation Plant J. C. Chen, R. Luo, S. Mu, Z. Zhang, M. Andersen, and P. E. Jørgensen Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000581 Posted ahead of print 16 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract The operating energy efficiency of Ulu Pandan MBR plant is optimized by Artificial Neural Network (ANN) and bioprocess models. The ANN model mines historical plant data to uncover optimal operating settings. Historical plant data indicate that adjusting the membrane scouring aeration cycle will lead to direct energy savings. The ANN model concurs and shows the same correlation. Changes to plant operations carry substantial risk to the stability of the plant and hence place limitations on the range of operational variations. A plant risk assessment is conducted to ascertain the risk proposition for the adjustment of operating parameters. The bioprocess model investigates the underlying biological treatment mechanisms to identify the impact of solids retention time on the volatile suspended solids, soluble microbial products, and endogenous decay coefficient. Results of the modeling show qualitatively good agreement with measured operating data. The concentrations of volatile suspended solids (VSS) and soluble microbial products (SMP), as well as, the endogenous decay coefficient are shown to be sensitive to the system solids retention time (SRT).

Select this Article		Application of Ferric Chloride for Removal of Glyphosate: Modeling of Axial and Radial Flow Impellers Using Artificial Neural Networks M. Mohsen Nourouzi, T. G. Chuah, and Thomas S. Y. Choong Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000580 Posted ahead of print 13 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract This paper studied the removal of herbicide Glyphosate in aqueous solution using ions capable of forming an insoluble complex Glyphosate salt (ferric Chloride). A maximum Glyphosate removal of 67.4% was achieved using 300 mg/L of ferric chloride. The precipitation of the insoluble Glyphosate salt was affected by rapid mixing velocity, rapid mixing time, dosage of flocculant and types of impellers. An artificial neural networks (ANN) model was used to predict the removal of Glyphosate. The results showed good agreement over the range of experimental and predicted data. Increasing the velocity gradient increased the Glyphosate removal. The Glyphosate removal decreased with further increase in shear stress. At higher flocculant dosage, the effect of impeller shear is less as the flocs are stronger. The results showed that the effect of impeller type was highly dependent on the rapid mixing velocity and rapid mixing time.

Select this Article		Hybrid Process Combining Electrocoagulation and Electro‐Oxidation Processes for the Treatment of Restaurant Wastewaters Rimeh Daghrir, Patrick Drogui, Jean François Blais, and Guy Mercier Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000579 Posted ahead of print 12 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract The present study investigates the electrocoagulation‐electro‐oxidation process (EC‐EO process) for the treatment of restaurant wastewater (RWW) loaded with organic and inorganic matter, oil and grease and suspensions solids. The EC‐EO process was firstly evaluated in terms of its capability of simultaneously producing an oxidant and coagulant agents using either iron or aluminum electrodes arranged in bipolar configuration and graphite electrodes arranged in monopolar configuration in the same electrolytic cell. Relatively high concentrations of active chlorine (9.6 mg/(min.A)) and aluminum (20 – 40 mg Al/L) or iron (40 – 60 mg Fe/L) were in‐situ produced. The best performance for RWW treatment was obtained using aluminum and graphite plates alternated in the electrode pack and operated at current of 0.4 A during 90 min of treatment with pH adjustment around 7.0. Under these conditions, more than 98% of O&G was removed, whereas COD and BOD removal reached 90% and 86%, respectively. Likewise, more than 88% of soluble phosphate was removed and the process was also found to be effective in removing turbidity (98%) and suspended solids (98%). The EC‐EO process operated under the best conditions involved a total cost of 1.56 ± 0.01 US$ per cubic meter of treated restaurant effluent. This cost includes energy and electrode consumptions, chemicals and sludge disposal.

Select this Article		Use of Simulation Filters in 3‐Dimensional Groundwater Contaminant Transport Modeling Godwin Appiah Assumaning, BS, MS and Shoou‐Yuh Chang, Ph.D., P.E. Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000578 Posted ahead of print 12 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Contaminants have been modeled using numerical models to predict their fate and transport. These models are simplified by introducing approximation that plagues the model with truncation and round‐off errors. In order to improve the accuracy and effectiveness of contaminant concentration prediction, three simulation techniques such as Particle, Kalman and Extended Kalman filters were used in this research as a tool to model the groundwater contaminant using a 3‐Dimensional (3‐D) subsurface advection‐dispersion‐reaction model. The 3‐D model was discretized spatially and temporally using the Forward‐Time‐Central‐Space (FTCS) method. A total of 18 observation points were used to run the simulation filters. The dynamical models used by the simulation filters are embedded with random Gaussian noise to mimic a real life situation. The Kalman and Extended Kalman filters also have an advantage of storing only the previous estimate to make a new prediction. The Particle filter however, applies sequential Monte Carlo method and probability density functions to make estimates. The filters are capable of providing a better prediction than the numerical method when sparse observation data are used. The algorithms to generate the simulation and the numerical results were run on Matlab 7.1. The effectiveness of the prediction results were assessed using the Root‐Mean‐ Square Error (RMSE), Mean‐ Absolute‐Error (MAE) and Maximum‐Absolute‐Error (E_max) equations. The results show that the filters perform better than the numerical method. The filters are capable of reducing the error in the numerical results by approximately 70%.

Select this Article		Effect of Urban Catchment Composition on Runoff Temperature Matthew P. Jones, Ph.D., William F. Hunt, Ph.D., P.E., and Ryan J. Winston Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000577 Posted ahead of print 12 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Urban runoff adversely impacts cold‐water stream environments due to sporadic fluxes of thermally enriched runoff. This has adverse impacts on tourism in regions that support trout and salmon streams. Research on stormwater control measures (SCMs) has shown that meeting the 21°C trout threshold is not consistently feasible with current SCM technologies. Thus, it is important to consider other factors in stormwater temperature management, such as catchment characteristics. Median and maximum runoff temperatures from a shaded parking lot were consistently lower than those from a nearby unshaded lot. This suggests the need for implementation of tree canopy cover in trout sensitive catchments. A light colored chip seal pavement was compared to a traditional hot mix asphalt pavement; the light colored chip seal produced median stormwater temperatures that were 1.4°C lower than the standard hot mix asphalt. It was shown that runoff temperature measurement location is critical when evaluating SCM performance, and that underground conveyances can reduce runoff temperature substantially.

Select this Article		Influence of Process Parameters on the Characteristics of Struvite Pellets Kazi P. Fattah, Donald S. Mavinic, and Frederic A. Koch Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000576 Posted ahead of print 10 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract With an ever increasing demand for phosphate‐based fertilizer, new sustainable sources of phosphorus are warranted. Recent technologies have successfully demonstrated the possibility of recovering phosphorus from wastewater treatment plants as struvite, which is also a readymade, slow‐release fertilizer. However, process parameters that influence the operation of crystallizers and production of good quality struvite pellets have yet to be fully understood. This paper discusses the influence of process parameters on the characteristics of struvite pellets. Among the various process parameters, upflow velocity and flow patterns in the crystallizer were found to influence the size and shape of the pellets. In the range (1.5–7.1) tested, supersaturation ratio did not appear to influence the crushing strength of the pellets formed. Mid‐sized pellets, in the 2.0–2.5 mm range, exhibited the highest crushing strengths. Higher magnesium concentration in the crystallizer was able to increase the crushing strength of struvite pellets by as much as 15% — 27%.

Select this Article		Are Bioretention Cells Being Installed Per Design Standards in North Carolina? A Field Assessment Brad J. Wardynski, S. M. ASCE and William F. Hunt, III, P.E., M. ASCE Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000575 Posted ahead of print 10 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Forty‐three bioretention cells (BRCs) throughout North Carolina were assessed for maintenance needs, soil media composition, and as‐built surface storage volume to determine whether BRCs are typically constructed per their intended design specifications. Visual inspections identified hydric soils and redoximorphic features (indicators of prolonged anaerobic conditions) and quantified the occurrence of issues requiring maintenance. Particle‐size distribution and permeability of soil media were measured at multiple locations within each cell and topographic surveys were performed to calculate as‐built surface storage volumes. Field drawdown tests were used to verify permeability measurements and assess overall BRC function. Of the studied cells, 22% contained redoximorphic features in the upper 30 cm, and 53% were in need of maintenance due to one or more factors. Although 71% of assessed cells failed to meet soil media particle‐size distribution specifications, 98% of BRCs contained media with adequate or high permeability. Over half (65%) of cells were undersized vis‐à‐vis intended design, with 53% exhibiting moderately or severely undersized surface storage capacity. Discrepancies in average ponding depth and incorporation of inspection/maintenance programs significantly influenced the accuracy of as‐built BRC storage volume; therefore it is important for inspectors to verify that the bed elevations of BRCs have been accurately graded. Despite being typically undersized, it was concluded that most observed bioretention cells are meeting the hydrologic goals of North Carolina standards.

Select this Article		Worldwide Regulatory Guidance Values for Chlorinated Benzene Surface Soil Contamination Emily S. Kowalsky, M. ASCE and Aaron A. Jennings, Ph.D., P.E., M. ASCE Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000574 Posted ahead of print 10 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Surface soil contamination is a worldwide problem that is often addressed by the use of regulatory guidance values (RGVs) that establish the maximum amount of contamination that may exist without prompting a regulatory response. Chlorinated benzenes are a family of 12 synthetic aromatic contaminants for which at least 168 jurisdictions have promulgated guidance values. Analysis of the 973 RGVs for the eight most commonly regulated chlorinated benzenes is presented. The RGVs of chlorobenzene, 1,2‐, 1,3‐ and 1,4‐diclorobenzene, 1,2,4‐trichlorobenzene, 1,2,4,5‐tetrachlorobenzene and hexachlorobenzene vary by over six orders of magnitude. The RGVs for pentachlorobenzene vary by five orders of magnitude. The RGV distributions resemble those of lognormal random variables, but contain non‐random clusters and extreme values that deviate from the lognormal distribution model. Point clusters appear to reflect the influence of organizations such as the U.S. Environmental Protection Agency (USEPA) and the Canadian Council of Environmental Ministers. Uncertainty analysis applied to the USEPA RGV derivation model indicates that only about 39% of all RGVs fall within easily justified uncertainty ranges. Methods are discussed to help reduce the remaining RGV variability.

Select this Article		Effect of Heavy Metals on Bacterial Attachment in Soils Haibo Zhang and Mira S. Olson Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000573 Posted ahead of print 26 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract The presence of both heavy metals and bacteria is frequently reported in urban stormwater runoff. Adsorption and complexation of metals onto bacteria and soil takes place as stormwater runoff infiltrates into the subsurface, potentially changing both bacterial and mineral surfaces, and altering the attachment of bacteria onto soil surfaces. Scanning electron microscopy and energy dispersive X‐ray spectroscopy analyses were performed on soil samples equilibrated with synthetic stormwater amended with copper, lead and zinc to determine changes in the elemental content of soil. Sets of batch sorption experiments of Escherichia coli onto soil were conducted under different conditions by varying solution composition and soil exposure history. E. coli attachment increases in synthetic stormwater with elevated heavy metals concentrations (K_d= 0.0229mL/mg) as opposed to nutrient buffer (K_d= 0.0100mL/mg) for the same untreated soil. For E. coli both suspended in nutrient buffer, K_d is higher when equilibrated with metals‐treated soil (K_d= 0.0119mL/mg) in comparison with untreated soil (K_d= 0.0100mL/mg). Results indicate that the presence of heavy metals in solution increases bacterial attachment to soil surfaces.

Select this Article		Statistical Modelling of Contaminants Removal in Mature Integrated Constructed Wetland Sediments Yu Dong, Miklas Scholz, and Rory Harrington Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000572 Posted ahead of print 26 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract Multiple regression models, principal component analysis (PCA), redundancy analysis (RDA), and the self‐organizing map (SOM) model were applied to assess the effects of physico‐chemical parameters on the treatment performance of contaminated wetland sediments in replicate integrated constructed wetland (ICW) mesocosms treating either farmyard runoff or domestic wastewater. Dissolved oxygen (DO) concentration and conductivity were correlated with the reduction of ammonia‐nitrogen (NH₄‐N) and/or molybdate reactive phosphorus (MRP), and the redox potential (RP) and conductivity were related to chemical oxygen demand (COD) removal. SOM was selected as the prediction model to provide numerical estimations for the performance of ICW mesocosms. The model was validated, indicating that NH₄‐N, MRP, and COD removal can be predicted by input variables which are quick and cost‐effective to measure. The SOM model is an appropriate method for monitoring the performance of mature ICW being a source of some contaminants such as nitrogen and phosphorus. Although no reduction in the overall performance has been noted for ICW sites 7 and 11, this laboratory‐scale study provides valuable warning signs regarding the loss of contaminant removal for ICW systems that are in operation for a relatively long time.

Select this Article		Environmental Factors Influencing the Abundance of Enterococci in Gulf Coast Beach Waters Kevin M. Chenier, M. Teresa Gutierrez‐Wing, Zhi‐Qiang Deng, and Kelly A. Rusch, P.E. Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000571 Posted ahead of print 26 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract Enterococci concentrations in seawater samples collected in 2010 at a Gulf Coast beach in the afternoon were significantly lower (12 MPN/100mL) compared to morning samples (172 MPN/100 mL). The factors affecting temporal differences of enterococci concentration in beach waters were studied through five laboratory experiments analyzing beach sands, solar radiation, salinity, and turbidity. Enterococci were found in beach sands at a geometric mean of 43 MPN per 100 g of sand, demonstrated the ability to persist for extended periods of time, and increased when incubated (geometric mean of 54 MPN per 100 g sand). Solar radiation inactivated large enterococci concentrations (≥24,196 MPN/100mL) in as little as four hours in salinities ranging from 0 to 25 parts per thousand (ppt). Increased turbidity (70 and 140 NTU) hindered the effect of solar radiation, suggesting that near‐shore turbidity may promote higher enterococci concentrations. The results indicate that enterococci replenishment along Gulf coastal waters is not due to reactivation as found in other areas. This work illustrates that beach sands, solar radiation, salinity, and turbidity impact enterococci concentrations in Gulf Coast beach waters.

Select this Article		Determining Minimum Ion Exchange Resin Usage for NOM Removal Shaoying Qi, Lance C. Schideman, and Treavor H. Boyer Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000569 Posted ahead of print 16 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract For design and analysis of an ion exchange (IEX) process, it is necessary to know the minimum IEX resin usage defined thermodynamically. In this article, we recognize that anion exchange resin sorption of dissolved natural organic matter (NOM) may follow an isotherm of either type I or type II that are noticeably different at high surface coverage. The charge density of NOM, which monotonically increases with the pH, appears to play a critical role. Basic pH (high charge density) favors a type I isotherm while acidic pH (low charge density) may change the isotherm to type II. The Langmuir equation and the Wiegner‐Jenny‐Summers‐Roberts (WJSR) equation can be used to quantify the type I and the type II isotherms, respectively. Explicit relationships between minimum resin usage and desired level of removal are subsequently developed and the isotherm constants along with the non‐removable NOM fraction are estimated simultaneously by an innovative least squares regression (LSR) approach. The Langmuir isotherm based model describes the sorption removal of type I isotherm well while the WJSR isotherm based model describes the sorption removal of type II isotherm well. At removals >30%, though, the two sorption models give comparable minimum IEX resin usages. The sorption models and the LSR methods developed herein are applicable to resin slurry contactors including batch reactors, plug flow reactors, or continuous‐flow stirred tank reactors (CSTRs).

Select this Article		Enhanced Adsorptive Removal of Cadmium from Water By Immobilized Hydrophobic Ionic Liquids on Nano‐Silica Sorbents Mohamed E. Mahmoud and Hassan M. Al‐bishri Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000568 Posted ahead of print 14 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract Excellent adsorptive removal of cadmium from a pH 1.0 adjusted acidic aqueous solutions was accomplished by using two physically loaded ionic liquids with various hydrophobicity, [Emim ⁺Tf₂N⁻] and [Omim ⁺Tf₂N⁻], on nano‐silica sorbents, [Nano‐Si‐OH‐Emim ⁺Tf₂N⁻] and [Nano‐Si‐OH‐Omim ⁺Tf₂N⁻], respectively. Adjusted solutions to a pH 1.0 were found to produce the highest cadmium adsorption capacity values (1.200–1.300 mmol g⁻¹). Anion exchange mechanism was proposed for such high adsorption of cadmium via exchange of anionic cadmium species by [Tf₂N⁻] anion. Several operational controlling factors including the reaction pH, reaction time, sorbent dose, initial cadmium concentration, interfering ions and hydrophobicity of ionic liquids were monitored and optimized. The more hydrophobic ionic liquid, [Omim ⁺Tf₂N⁻], was found to enhance the adsorption efficiency of modified sorbent in all evaluated controlling factors. Adsorption equilibrium modeling data were fitted to Brauner‐Emmet‐Teller (BET) and Langmuir models. The potential implementations of [Nano‐Si‐OH‐Emim ⁺Tf₂N⁻] and [Nano‐Si‐OH‐Omim ⁺Tf₂N⁻] were successfully established for cadmium removal. The percentage extraction values of cadmium from industrial waste water and drinking tap water samples, both adjusted to a pH 1.0, were found 97.25–99.30 ± 2.00–4.00 %. The determined percentage extraction values (94.11–98.47 ± 2.00–4.00 %) were also identified for the two water samples adjusted to pH 7.0 after three stages of micro‐column elution.

Select this Article		Long Term Orthophosphate Removal in a Field‐Scale Stormwater Bioinfiltration Raingarden John Komlos and Robert G. Traver, M.ASCE Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000566 Posted ahead of print 6 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract Unabated runoff from impervious surfaces after rain events is considered a major source of impairment of receiving water bodies. Bioinfiltration Stormwater Control Measures (SCM) have been shown to be effective in reducing runoff and pollutants from urban areas and thus provide a mechanism for protecting downstream sources from erosion and contamination from suspended solids, metals, and nutrients. However, less is known about the loss mechanisms responsible for contaminant removal and the long‐term performance of such SCMs. Even less is known of the performance from a vadose zone perspective. The research presented herein examines the long‐term (nine year) performance of a bioinfiltration raingarden with specific emphasis on the removal of orthophosphate. Field data indicated clear removal trends for orthophosphate (PO₄³‐P), the bioavailable form of phosphorus, as the stormwater infiltrated into the infiltration bed of the raingarden. The median PO₄³‐P concentration decreased from 0.21–0.25 mg/L in the ponded water to 0.03 mg/L in the pore water at the bottom of the infiltration bed. Overall, the raingarden showed no sign of decreased PO₄³‐P removal performance over nine years of monitoring. In addition to monitoring dissolved PO₄³‐P concentrations over time, soil samples were collected throughout the raingarden to quantify the accumulation of PO₄³‐P in the soil. Results show that PO₄³‐P was uniformly distributed throughout the top layer of the ponded area of the infiltration bed (0.13 ± 0.03 mg/g dry soil, n=4) and then decreased with depth between 0 cm and 10 cm. The sorbed PO₄³‐P concentrations remained relatively constant between the depths of 10 to 30 cm throughout the infiltration bed (0.05 ± 0.02 mg/g dry soil, n=20). A mass balance comparing the mass of PO₄³‐P entering and leaving the raingarden to the mass sorbed to the soil suggested that the extraction procedure used to remove the PO₄³‐P from the soil (0.5 N HCl for 24 hours) provided a rough estimate of the PO₄³‐P that accumulated during the nine years of operation. Comparison of the PO₄³‐P sorbed to the first 30 cm of soil over the nine years (1.58 kg or 176 g/year) to the maximum amount of PO₄³‐P that the soil can hold if in equilibrium with dissolved PO₄³‐P concentrations typical of the raingarden (0.05 – 0.11 mg/g dry soil, based on batch sorption experiments) indicated that the top 10 cm of the infiltration bed was saturated with PO₄³‐P but saturation of deeper depths would not occur for >20 years. This led to the conclusion that, in regards to the soil, infrequent maintenance is needed with respect to PO₄³‐P removal during the long‐term operation of the raingarden.

Select this Article		Fate of Endocrine Disrupting and Pharmaceutically Active Substances in Sand Columns Fed with Secondary Effluent Jinxia Ke, Karina Yew Hoong Gin, Lai Heng Tan, and Martin Reinhard Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000564 Posted ahead of print 1 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract Sorption and biotransformation of six endocrine disrupting compounds (EDCs) (estrone (E1), 17β‐estradiol (E2), estriol (E3), 17α‐ethynylestradiol (EE2), 4‐tert‐octylphenol (4‐t‐OP), bisphenol A (BPA)) and two pharmaceutically active compounds (PhACs) (ibuprofen (IBU) and naproxen (NAP)) were studied in microcosm and columns under conditions that simulate the percolation of effluent through sandy soil on reclaimed land in Singapore. Sorption isotherms followed a linear model except for IBU and BPA, where a Freundlich model was used, and for NAP, which sorbed too little to be measurable. Degradation experiment results showed that aerobic conditions were more favorable for the degradation of EDCs than anaerobic or anoxic conditions. E3 and 4‐t‐OP were totally removed within 40 days, while EE2, BPA, IBU and NAP were persistent. However, under anaerobic conditions, E1 was formed from E2 and vice versa, reaching steady state conditions after about 15 days. In order to simulate the groundwater recharge condition, eight laboratory‐scale soil aquifer treatment (SAT) saturated sand columns (length of 1.0 m each) were operated in series. Secondary and ultrafiltered effluent augmented with the target compounds was applied to two identical sets of eight columns respectively. With secondary effluent (SE) and ultrafiltered SE as the feed, the target compounds were completely removed after 8 m of infiltration with the exception of NAP, which persisted at 1 μg/L in the effluent of recharged columns after an operating time of 3 pore volumes. The higher removal rate in SE recharged columns is attributed to the higher nutrient content, microbial populations as well as the longer period of acclimatization. Small‐scale batch studies showed that E2, EE2, IBU and NAP removal was primarily due to biological transformation that was faster under aerobic than anaerobic conditions.

Select this Article		Experimental Study on Chromium Containment by Admixed Soil Liner Sudipta Ghosh, Somnath Mukherjee, Kunal Sarkar, Ashraf Z. Al‐Hamdan, A. M. ASCE, and Krishna R. Reddy, M. ASCE Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000563 Posted ahead of print 27 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Chrome tanneries generate large quantities of chromium‐laden sludge which require proper disposal in engineered landfills to prevent contamination of subsurface soils and groundwater and reduce the risk to public health and the environment. This study investigates the feasibility of using a fine‐grained soil as a suitable landfill liner material for the effective containment of chromium in the sludge leachate. Several series of laboratory permeability, adsorption and column tests were conducted using the soil without and with selected additives (rice husk, bentonite, and fly ash) to determine permeability and adsorption and transport of chromium in the soil. Permeability tests showed that the field soil amended with 17% rice husk and 2% bentonite provides the desired hydraulic conductivity of 10⁻⁷ cm/s (or less) to minimize the leachate migration into the surrounding subsurface environment. The rice husk and bentonite admixtures significantly reduced the hydraulic conductivity of the soil from 3×10⁻⁷ to 2.8×10⁻⁹ cm/s, and this admixture was further tested for its effect on the adsorption and transport of chromium in the soil. The batch kinetics and column tests results showed that the soil possess relatively high chromium adsorption capacity under natural or slightly alkaline condition. The batch tests showed the amendment marginally improved the chromium adsorptive capacity of the soil. The column tests showed slight increase in breakthrough time due to the presence of amendment. The inclined base column tests showed that a mildly inclined liner configuration has a marginal effect on the chromium attenuation in the soil. Overall, this study showed that the soil amended with 17% rice husk and 2% bentonite decreased the hydraulic conductivity of the soil significantly and slightly increased the adsorption of chromium; therefore, has the potential for usage as a landfill liner in landfill system to contain chromium contamination.

Select this Article		Stacked Filters: A Novel Approach to Rapid Sand Filtration Michael J. Adelman, Monroe L. Weber‐Shirk, Ph.D., M. ASCE, Anderson N. Cordero, Sara L. Coffey, William J. Maher, Dylan Guelig, Jeffrey C. Will, Sarah C. Stodter, Matthew W. Hurst, and Leonard W. Lion, Ph.D. Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000562 Posted ahead of print 27 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Rapid sand filters are a familiar and mature technology, but the mechanical sophistication they incorporate in industrialized nations limits their sustainable application in developing countries. Conventional rapid sand filters require pumps, elevated tanks, or multiple filter units to generate high flow rates for backwashing. Stacked rapid sand filtration is introduced here as a more robust and sustainable alternative. A stacked rapid sand filter can backwash itself with no additional flow, which eliminates the need for pumps or other expensive equipment. This study presents laboratory and field proof‐of‐concept demonstrations of this novel technology. The multi‐layer configuration of stacked rapid sand filters allowed a laboratory unit to be loaded at 1.4–1.83 mm/s (120–160 m/day) per layer and backwashed at 10–11 mm/s (860–950 m/day) with the same or similar total flow rate. The filtered effluent met U.S. EPA drinking water standards. The backwash cycle was also demonstrated, and flushing of contaminants from the sand bed was effective even with 5–10 NTU backwash water. A test stacked filter unit also demonstrated satisfactory filtration performance and effective backwashing at several water treatment plants in Honduras.

Select this Article		Bench Scale Study of Electrochemical Oxidation for On‐Site Treatment of Polluted Groundwater Jens Muff, Henrik Jepsen, and Erik Søgaard Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000561 Posted ahead of print 27 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Electrochemical oxidation has been studied in a series of bench scale tests as a physico‐chemical oxidation technique for on‐site treatment of a very complex polluted groundwater containing pharmaceuticals, chlorinated solvents, BTEX and inorganic salts. Two different cells were applied, one with Ti/Pt90‐Ir10 as anode material and one with Si/BDD anode material representing two different classes of anode materials for organic oxidation. COD and TOC analysis were used to assess the performance, and the influence of change in recirculation flow and applied current density was studied. Si/BDD showed the highest ICE of 0.17 at 50 mA cm⁻², but further optimization at lower currents closer to the limiting currents are needed for the process to be economically attractive. Si/BDD showed a superior TOC removal resulting in full mineralization of the organic groundwater contaminants compared to the higher degree of partial oxidation obtained by Ti/Pt₉₀‐Ir₁₀. Model consideration showed the importance of bulk oxidation by generated oxidants using the Ti/Pt₉₀‐Ir₁₀ anode and the high dependence of this process on the flow conditions and applied current.

Select this Article		Start‐up Performance Evaluation of Submerged Membrane Bioreactors Using Conventional Activated Sludge Process and Modified Luzack—Ettinger Process Zhihua Liang and Zhiqiang Hua Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000559 Posted ahead of print 25 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract The rising trend of converting conventional activated sludge processes to membrane bioreactor (MBR) processes for water reuse requires studying the start‐up performance of bioreactors, during which mixed liquid suspended solids concentrations increase significantly. One conventional activated sludge MBR (CAS‐MBR) and one modified Luzack—Ettinger (MLE) type MBR (MLE‐MBR) with mixed liquor recirculation were evaluated for their performance on organic and nutrient removal, membrane fouling, biomass characteristics and bacterial activities during the start‐up period. The two bench‐scale MBRs had identical reactor volume (7.2 L) and were operated under continuous flow conditions with no sludge wasting during the start‐up operation. It took about 130 days for the MBR biomass concentrations to increase from initial 2500 mg biomass COD/L to a final concentration of 13000 mg COD/L with net specific biomass growth rates of 0.0125 day⁻¹ and 0.0127 day⁻¹ for the CAS‐MBR and MLE‐MBR, respectively. The total nitrogen removal efficiency of the MLE‐MBR was 73%, higher than that of the CAS‐MBR (44%) while both MBRs had excellent organic removal (> 99%) soon after the start‐up operation. Because of sequencing anoxic and aerobic operations, the biomass of the MLE ‐MBR exhibited higher heterotrophic and autotrophic respiration activities and better sludge settling than that of the CAS‐MBR. Furthermore, the MLE‐MBR experienced less membrane fouling than the conventional MBR. Results of the start‐up performance suggest alternating anoxic/aerobic MBR operations improve wastewater nutrient removal, increase bacterial activities, and reduce membrane fouling.

Select this Article		Mass Transfer Kinetics of Phosphorus to Filter Media from Wastewater, Stormwater and Surrogate Matrices Tingting Wu and John Sansalone Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000558 Posted ahead of print 25 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Granular media are increasingly utilized for control of phosphorus (P), frequently indexed as total P (TP), which represents the sum of particulate (PP) and dissolved P (DP) fractions. The fate of PP notwithstanding; when such media are deployed for control of DP the mass transfer kinetics from an aqueous matrix to the media is important for design and modeling tools. In this paper, the mass transfer of DP for a suite of common media are monitored and modeled with a focus on comparing the behavior of Al‐oxide coated media (AOCM) subjected to synthetic‐ and actual runoff (wet weather) as well as wastewater (dry weather) matrices. The media employed were AOCM_c (clay based), AOCM_p (pumice based), and AOCM_pcc (Portland cement concrete based), and their corresponding media (UCM) substrates. A 2^nd order potential driving model is utilized for the overall TP transfer rate from aqueous solution to AOCM, while an intra‐media diffusion model illustrates diffusion rates. In comparison to AOCM forms that demonstrate similar and rapid kinetics (lower for AOCM_p), other media exhibited large variability, decreasing in order from Fe‐coated perlite, activated alumina, expanded shale and bioretention media. In contrast, Zeolite‐perlite‐GAC (granular activated carbon) and tire‐crumb (Black and Gold, B&G) displayed net adsorption not significantly different from 0 (p = 0.05). Comparing synthetic‐ and actual runoff matrices demonstrated that actual runoff produced slower kinetics for AOCM_c and AOCM_p, primarily due to the presence of competitive ions (SO₄²⁻), while elevated Ca²⁺ at the alkaline surface of AOCM_pcc offset the effect of SO₄²⁻, through surface precipitation.

Select this Article		Effectiveness of Air Stripping, Advanced Oxidation, and Activated Carbon Adsorption‐Coupled Process in Treating Chlorinated Solvents‐Contaminated Groundwater Bingzhi Li, Kuangfei Lin, Wei Zhang, Shuguang Lu, and Yongdi Liu Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000557 Posted ahead of print 23 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Chlorinated solvents are the most prevalent organic contaminants in groundwater because of their extensive and widespread use as cleaning agents and metal degreasers, and they have become a significant threat to groundwater supplies. Groundwater contamination by chlorinated solvents has proven difficult and costly to remedy because of the physicochemical properties of the solvents. This study was conducted to examine the effectiveness of treating contaminated groundwater containing chlorinated solvents using air stripping, advanced oxidation, and activated carbon adsorption processes. The results showed that the stripping instrument could effectively transfer chlorinated solvents into the gas phase within several minutes at an airflow rate of 5.0 L/min and a temperature of 298 K. The residual chlorinated solvents were further oxidized into harmless by‐products by the subsequent O₃/H₂O₂ process, and the off‐gas generated from the above processes were collected and absorbed by four types of activated carbons (i.e., Shanghai coconut, Shanghai fruit, Taixi coal (12*40) and Taixi ZJ‐15 (cylinder)). Shanghai coconut exhibited the greatest adsorption capacity, at 0.5 g/g. Two types of contaminated groundwater containing chlorinated solvents from contaminated sites were successfully treated by the coupled process at bench scale with the effluent concentrations of chlorinated solvents complying with the target values standard for groundwater regulated by the Dutch Ministry of Public Housing. Overall, the study found that the proposed coupled process is a viable method for efficiently and effectively remediating shallow contaminated groundwater containing chlorinated solvents in Southern China.

Select this Article		Physical Modeling of Particulate Matter Washout from a Hydrodynamic Separator Hwan Cho and John Sansalone Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000556 Posted ahead of print 23 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract A hydrodynamic separator (HS) is commonly used as a preliminary unit operation for separation of particulate matter (PM) and PM‐associated constituents transported by urban rainfall‐runoff. Although the small spatial footprint of an HS is advantageous for integration into sewer (storm or combined) or drainage systems, the small footprint also concentrates flow energy. In many HS units where PM sludge is not isolated or in units that are not maintained (cleaned), washout of previously separated PM sludge can result in a net export of PM. This study analyzes PM washout from a baffled HS as a function of steady flow rates and particle size distributions (PSDs), guided by a physical modeling framework utilized for “scour” certification. The HS hydraulic signature is determined through velocity measurements and a residence time distribution (RTD) analysis. As a function of surface overflow rate (SOR), the pre‐deposited PM washout rate ranges from 0.4 to 13.3 g/min. for fine PM {SM I,< 75 μm}, from 0.3 to 4.9 g/min. for moderately‐coarser PM {SM II,< 100 μm} and 0.2 to 3.1 g/min. for coarser PM {SM III,<1000 μm} as SOR ranges from 47 L/min‐m² (0.91 L/s) to 581 L/min‐m² (11.31 L/s). The washout rate decreases with time for each hetero‐disperse PM gradations and the evolution of HS washout is modeled as a 1st order exponential analogous to urban washoff models. Washout from the HS is modeled as a function of the densimetric Froude number and SOR. Results indicate that washout based on a Shields approach cannot be applied to HS units.

Select this Article		An Enhanced HSPF Model Structure for Chesapeake Bay Watershed Simulation Gary W. Shenk, Jing Wu, and Lewis C. Linker Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000555 Posted ahead of print 21 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract For more than two decades, an HSPF‐based watershed model has been used to simulate nutrient and sediment load delivery to the Chesapeake Bay. Over time, the watershed model has increased in complexity commensurate with the management challenges in Chesapeake Bay restoration. The increased complexity poses challenges to the standard application of HSPF for efficient operation of the model in a large‐scale watershed, as well as difficulties in incorporating changes in Best Management Practices (BMPs) and land uses over time. In response, the U.S. Environmental Protection Agency's Chesapeake Bay Program Office developed a software solution that enhances the existing HSPF model structure. The software system, consisting of preprocessors, an External Transfer Module, and postprocessors, was devised to conveniently generate and update parameter files essential to operations of a large and complex watershed modeling system and to implement land use and nonpoint source pollution management changes on any time scale greater than or equal to daily. The developed model system is demonstrated through comparison of the hydrologic calibrations of the current Phase 5 model and the previous Phase 4.3 model at 14 stations as well as by several key scenario runs. The results show that the combined upgrades in segmentation, input data, and functionality improved model calibration, however simply incorporating changes in land use did not significantly improve model calibration. The developed software provides a means to represent the key forcing functions in more detail and to address issues of flexibility that are difficult to manage in traditional HSPF applications.

Select this Article		Unique Superposition Solution of Multiple Plane or Round Buoyant Jets for Tracer and Buoyancy Fluxes Panayotis C. Yannopoulos Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000554 Posted ahead of print 21 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract The present work proves the uniqueness of the superposition solution, regarding tracer or buoyancy, for parallel multiple (plane or round) turbulent buoyant jets with positive buoyancy, in general, which are discharged vertically upwards into a still environment from sources of relatively short spacing. The multiple plane buoyant jets are of infinite length, while the multiple round buoyant jets may form groups of any arrangement shape. The proof is based on the observation that the partial differential equation of tracer or buoyancy conservation becomes linear with respect to the mean tracer or buoyancy fluxes of single plane or round turbulent buoyant jets, which simultaneously satisfy the aforementioned equation. Alternatively, the validity of similar assumptions to the Reichardt's hypothesis, for either plane or round turbulent buoyant jets has been verified. Findings denote that the solution of a group of interacting buoyant jets with respect to the tracer or buoyancy fluxes can be uniquely obtained by superimposing the particular solutions corresponding to each single buoyant jet of the group. In addition, the superposition method is suitably applied to predict the profiles of the tracer or buoyancy flux above a finite two‐dimensional or three‐dimensional source.

Select this Article		Efficient Removal of Cd²⁺ from Aqueous Solutions by Adsorption on PS‐EDTA Resins: Equilibrium, Isotherms and Kinetic Studies Xiaoli Li, Liuqing Yang, Yanfeng Li, Zhengfang Ye, and Aixiao He Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000553 Posted ahead of print 21 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Batch adsorption experiments were conducted using environment‐friendly prepared chelating PS‐EDTA resins as an adsorbent to adsorb Cd²⁺ from aqueous system in which experimental parameters were studied including solution pH, adsorbent dose, contact time, initial metal concentration and temperature. The Langmuir, Freundlich and Dubinin‐Radushkevich (D‐R) isotherm models were employed to analyze the experimental data among which Freundlich isotherm model was found to be suitable for Cd²⁺ adsorption. In addition, Cd²⁺ adsorption on PS‐EDTA resins fitted well to the pseudo‐second‐order kinetic model. Intraparticle diffusion studies revealed that surface adsorption and intraparticle diffusion were both involved in the adsorption of Cd²⁺ ions. Thermodynamic parameters such as Gibbs free energy (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) were calculated and indicated that adsorption of Cd²⁺ ions onto PS‐EDTA resins was a spontaneous and endothermic process. The effects of various salts and co‐existing heavy metal ions on Cd²⁺ ions adsorption were also investigated. Moreover, the results from the sequential adsorption—desorption cycles showed that PS‐EDTA resins held good reusability and this could be a potential application in the fixed‐bed continuous‐flow column for the removal of heavy metals.

Select this Article		Groundwater Geochemical Characterization of a Fuel Contaminated Fractured Bedrock in a Permafrost Environment Olumide Iwakun, Ania Ulrich, Kevin Biggar, and David Sego Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000552 Posted ahead of print 16 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Remediation of a contaminated site to site‐specific cleanup standard requires a good understanding of the geochemical characteristics of the site. In this study, the groundwater hydrochemical characteristics of a fuel‐contaminated Colomac mine site in the Northwest Territories (Canada) was evaluated to understand the active geochemical processes and assess the groundwater quality in comparison to Canadian Council of Ministers of the Environment (CCME) guideline for the protection of freshwater aquatic life. Groundwater samples were taken from installed monitoring wells across the site and analyzed by field and laboratory methods for dissolved metals, ions, and BTEX (i.e., benzene, toluene, ethylbenzene, and xylenes) organic constituents. The results showed that the groundwater is Ca — SO₄ type due to ubiquitous occurrence of gypsum dissolution and carbonate weathering. Last sampling at the site showed that the BTEX constituents of interest were above the CCME limits in some locations but other geochemical indicators showed biodegradation is occurring at the site. The inorganic parameters of interest were generally less than the CCME limits with few outliers except iron, aluminum, and nickel. Iron and aluminum have background concentrations above the CCME limits. This study underscores the importance of mineralogical composition of the native bedrock on groundwater geochemical processes.

Select this Article		Effects of Media and Plant Selection on Biofiltration Performance Michael E. Barrett, P.E., M. ASCE, Maëlle Limouzin, and Desmond F. Lawler, P.E. Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000551 Posted ahead of print 9 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract The goal of this research was to compare the pollutant removal effectiveness of biofiltration systems containing different media and plant species. A laboratory column study was conducted using three media and two plant species, each with and without a submerged zone intended to promote denitrification. Twenty experiments using synthetic stormwater were run over the course of nine months and ten of them were analyzed. The three media used were concrete sand, masonry sand, and a medium that meets the City of Austin biofiltration specifications. The plant species were Buffalograss 609 and Big Muhly, both commonly found in Texas. The results of this study show a significant improvement in nutrient removal with the presence of these plants in the filter. The columns without plants were found to export substantial amounts of nitrate/nitrite, whereas the columns with the plants demonstrated substantial removal of nutrients (total nitrogen 59–79% and total phosphorus 77–94%). Solids removal remained high through the entire set of experiments for all the columns (88–97%). Hydraulic conductivity experienced an initial rapid decrease in all the columns, but then stabilized.

Select this Article		Harvestable Nitrogen Accumulation for Five Stormwater Wetland Plant Species: A Trigger for Stormwater Control Measure (SCM) Maintenance? H. A. Lenhart, W. F. Hunt, M. ASCE, and M. R. Burchell Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000550 Posted ahead of print 6 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract As the use of constructed stormwater wetlands to treat stormwater runoff becomes more frequent, strategies for maintaining or increasing their pollutant removal over time must be examined. One potential strategy is plant harvesting at the water surface to remove nutrients that would otherwise be deposited back into the wetland during senescence. This technical note presents a “first look” at this strategy from a stormwater management perspective. Vegetation was harvested from two stormwater wetlands located in Smithfield and Pactolus, North Carolina, to evaluate the ability of five wetland plant species to sequester nitrogen. Biomass samples were collected from the following species of emergent vegetation: Pontederia cordata (Pickerelweed), Saururus cernuus (Lizard Tail), Scirpus cyperinus (Wool Grass), Sagittaria latifolia (Arrowhead) and Schoenoplectus tabernaemontani (Softstem Bulrush). Samples were collected immediately prior to senescence in September and October 2007 and analyzed for nitrogen content on a percent of biomass basis. At the Pactolus wetland the Pontederia cordata, Scirpus cyperinus and Schoenoplectus tabernaemontani biomass retained significantly (p<0.05) more nitrogen than Sagittaria latifolia and Saururus cernuus. At the Smithfield wetland, Pontederia cordata and Sagittaria latifolia biomass retained significantly more nitrogen than Scirpus cyperinus and Saururus cernuus. Wetland maturity appears to have a direct relationship to harvestable nitrogen which could explain why the relative amount of nitrogen sequestered in Scirpus cyperinus and Sagittaria latifolia varied between the two wetlands. A positive relationship existed between the density of harvested biomass and nitrogen removal for two species. To estimate the relative amount of harvestable nitrogen, a model for estimating total nitrogen loading in Coastal Plain watersheds in North Carolina was used to compare estimated inflow nitrogen mass to that which could theoretically be harvested. The harvestable N mass was greater than 20% of inflow nitrogen on an annual basis. Stormwater wetland plant harvesting as a maintenance activity has potential to supplement wetland nitrogen removal.

Select this Article		The Identification of the Naegleria Species in Natural Watersheds Used for Drinking and Recreational Purposes in Taiwan Po‐Min Kao, Bing‐Mu Hsu, Yi‐Chou Chiu, Nai‐Hsiung Chen, Kuan‐Hao Huang, and Shu‐Min Shen Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000549 Posted ahead of print 6 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Naegleria spp. is a free‐living amoeboflagellate, which is widespread in natural environments. Some Naegleria spp. cause fatal human infections and the most important source of these infections is water. This genus is recognized as a potential human pathogen, which causes primary amoebic meningoencephalitis. In this study, 211 water samples were collected from two watersheds in Taiwan. We detected the Naegleria spp. based on PCR amplification with a genus‐specific primer pair, and an investigation of Naegleria spp. in the Puzih River and Kaoping River in Taiwan. The percentage of positive samples obtained from the Kaoping River (21.8%) was higher than that from the Puzih River (0.6%). The presence/absence of Naegleria spp. within the water samples showed a significant difference with levels of water temperature and pH value. The most frequently identified Naegleria spp. was N. philippinensis (n=3), followed by N. clarki (n=2), N. gallica (n=2), N. americana (n=2). N. australiensis, N. dobsoni, N. gruberi, and N. schusteri were each detected once. The presence of Naegleria spp. should be considered a potential public health threat; therefore, regularly maintaining normally operated water treatment facilities and implementing effective management strategies are critical for protecting public health.

Select this Article		Engine and Duty Cycle Variability in Diesel Construction Equipment Emissions Saeed Abolhasani and H. Christopher Frey, Ph.D., Professor Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000548 Posted ahead of print 6 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract This paper explores methods for analyzing on‐board mass emissions data and developing modal models based on case study examples for nine selected nonroad construction vehicles. Data for these vehicles were obtained from the U.S. Environmental Protection Agency. Several modeling methods were explored, including stratification of the data into operating modes, supplementing the modal models with ordinary least squares regression, and multiple least squares regression. The modal approach offers the advantages of being conceptually the simplest, reducing the influence of autocorrelation in the model, and providing substantial explanatory power. The normalized relationship between predicted mode‐specific average emissions and exhaust flow is stable, similar, and consistent for all vehicles. For a given engine, the average emission rate can vary by more than a factor of two when comparing highest to lowest rates among different duty cycles. Some engines are common to different types of equipment, such as bulldozers and front‐end loaders. For a given type of equipment, such as bulldozers, average NO_x and CO₂ mass emission rates can vary by more than 50 percent depending on the duty cycle. Vehicle category‐specific modal models are recommended based upon on‐board second‐by‐second in‐use activity and emissions data and for use in new modeling tools to estimate emissions produced by nonroad construction vehicles.

Select this Article		An Adaptive Time Stepping‐Operator Splitting Strategy to Couple Implicit Numerical Hydrodynamic and Water Quality Codes Gaurav Savant and R. C. Berger Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000547 Posted ahead of print 6 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Hydrodynamic and water quality codes have been frequently linked. These have typically been linked with both the hydrodynamic and water quality models using similar explicit time steps, but for long term simulations implicit models are required. The water quality codes linked to these hydrodynamic codes are forced to perform their computations using the hydrodynamic time step even though utilizing the same might result in drifting of the water quality solution. This technical note presents the development and testing of an Operator‐Splitting derived method for linking hydrodynamic and water quality codes with adaptive time stepping. The resulting method provides high fidelity solutions that compare well to analytic solutions and lends itself for extension to various other transported quantities.

Select this Article		Rapid Small Scale Column Tests on the Adsorption of Arsenate by Cationic Surfactant‐Modified GAC W. F. Chen, S. Y. Lin, and M. T. Cheng Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000546 Posted ahead of print 4 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Cationic surfactants were employed to modify granular activated carbon (GAC) for the purpose of improving GAC's adsorption of arsenate from water. Rapid small column tests (RSSCTs) were set up to test the adsorption capacities. Results indicated that surfactant cetyltrimethylammonium chloride (CTAC) modification manifested the highest improvement in GAC's adsorption for arsenate. GAC modified by 2 mmol/L of CTAC was able to operate around 64,000 bed volumes before 10 μg/L of arsenate breakthrough as compared to 2,100 bed volumes for virgin GAC. GAC also performed much better than zeolite and bentonite both in surfactant retention and arsenic removal. Arsenate adsorption was affected by influent concentration, pH and presence of other anions. The impact of competitive anions on arsenate adsorption was in the order of PO₄³⁻>SO₄²⁻>NO₃⁻. Breakthrough test on tap water spiked with arsenate indicated that the modified GAC had high selectivity for arsenate and considerable amount of arsenate was removed though the influent contained interfering anions and TOC in concentrations magnitude higher than that of arsenate.

Select this Article		A Comparison of Hollow‐Fiber Ultrafilters to Pleated Capsule Filters for Surface and Tap Water Samples Using U.S. Environmental Protection Agency (EPA) Method 1623 Gina H. Kimble, James E. Amburgey, and Vincent R. Hill, P.E. Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000545 Posted ahead of print 4 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract EPA Method 1623 is designed specifically for the detection of Cryptosporidium and Giardia, but the method has some issues with low and variable recoveries. Ultrafiltration has been used effectively for microorganism recovery from water samples but is not approved by EPA. In order to determine the efficacy of using ultrafiltration, ten‐liter tap water and surface water samples were seeded with Cryptosporidium and Giardia and concentrated with either a pleated capsule filter or a hollow‐fiber ultrafilter. For Cryptosporidum, oocyst recovery in tap water was significantly higher for ultrafiltration (68%) versus the capsule filter (37%), while ultrafiltration recovered 65% of oocysts in surface water versus 61% for the capsule filter. However, Giardia cyst recovery was mixed. In tap water, the capsule filter produced a significantly better recovery (85%) of Giardia compared to ultrafiltration (63%), but the surface water ultrafiltration recovery (81%) was significantly better than the capsule filter recovery (40%). Overall, ultrafiltration recoveries were equal to or better for Cryptosporidium, but recoveries of Giardia were varied depending on the filter used and the type of water analyzed.

Select this Article		Adsorption of Acid Extractable Oil Sands Tailings Organics onto Raw and Activated Oil Sands Coke Christina C. Small, Ania C. Ulrich, and Zaher Hashisho Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000543 Posted ahead of print 2 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract The accumulation of organic contaminants in process‐affected (PA) water represents an environmental liability for oil sands operators. Oil sands coke is a promising adsorbent for removing dissolved organic carbon (DOC), which includes toxic acid‐extractable oil sands tailings organics (AEOSTO) found in PA water. The ability of raw and activated delayed and fluid coke to remove DOC and AEOSTO from PA water was assessed. Treatment with 5 g/L of activated delayed and fluid coke removed 91% of DOC and 92% of AEOSTO at levels of 36 mg/L and 60 mg/L, respectively. Heavy metal leaching of vanadium at 5.9 mg/L was observed for a 5 g/L application of activated delayed coke, representing a challenge to the approach. Microtox™ testing indicated that higher carbon doses of activated cokes were effective in reducing toxic biological response due to organic compounds; however, exposure to heavy metals increased the toxic effect with time. The proposed methodology should be coupled with an inorganic treatment technique for complete oil sands tailings water treatment.

Select this Article		Surface Structure and Photocatalytic Activity of Nano‐TiO₂ Thin Film for Selective Oxidation Zhong‐Min Wang, Endalkachew Sahle‐Demessie, Ashraf Aly Hassan, and Christopher Perrett Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000542 Posted ahead of print 1 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Controlled titanium dioxide (TiO₂) thin films were deposited on stainless steel surfaces using flame aerosol synthetic technique, which is a one‐step coating process, that doesn't require further calcination. Solid state characterization of the coatings was conducted by different techniques, including X‐ray diffraction spectrum, scanning electron microscopy and atomic force microscopy. The coated thin films were used in a gas phase photoreactor for the partial oxidation of hydrocarbons to alcohols and ketones as an alternative production method for the highly sought oxygenates. For this purpose, oxidation reaction of cyclohexane to form cyclohexanol and cyclohexanone was chosen as a model reaction. The effects of film thickness, anatase‐to‐rutile ratio and particle morphology on the reactivity of the catalyst were studied. Experimental results revealed that there is an optimal film thickness (between 400 and 700 nm) for the photooxidation process that gave a maximum rate of reaction. The yield and selectivity of TiO₂ increased with the increase of the film thickness up to 350–400 nm. The activity decreased with further increase in thickness. The influence of crystallographic structure of TiO₂ on partial oxidation of cyclohexane showed that the catalyst efficiency increased almost linearly with the increase of the anatase fraction between 20 to 95%. The coating technique that formed highly porous and soft aggregated TiO₂ thin films with rough morphology, showed lower photoactivity than the technique that formed fine particle and transparent thin film.

Select this Article		Effects of Chitin Purity and Proppant Loading on the Bioremediation of Chloroethenes Jennifer A. McElhoe and Rachel A. Brennan Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000541 Posted ahead of print 31 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract Hydraulic fracturing (or “fracking”) of substrates and proppants into contaminated soils is a developing, but understudied, practice of stimulating in situ bioremediation. In this work, three different purities of the substrate crab shell chitin (SC‐20, SC‐40, and SC‐80), two proppant loadings (sand:chitin mass ratios of 5:1 and 15:1), and three chloroethene concentrations (1 and 10 mg/L trichloroethene, and 1.5 mg/L cis‐1,2‐dichloroethene) were experimentally and statistically examined to determine their effects on halorespiration. The least refined crab shell, SC‐20, produced the greatest variety of electron donors, converted the highest percentage of contaminant mass to ethene, and supported a significantly greater Dehalococcoides population than the other substrates. Although influent chloroethene concentration and proppant loading did not significantly affect halorespiration (p‐values > 0.079), decreasing the proppant loading from 15:1 to 5:1 increased the longevity of electron donor production. These results indicate that funds need not be expended for purification of crab shell substrates, and that SC‐20 should be used with proppant loadings of 5:1 or lower to maximize the duration of electron donor production at sites with potential biodegradation rate limitations.

Select this Article		Investigation of Flow Patterns in Stormwater Retention Ponds Using CFD Sher Khan, Bruce W. Melville, Asaad Y. Shamseldin, and Christoph Fischer Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000540 Posted ahead of print 25 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract The use of computational fluid dynamics (CFD) as an engineering tool for the design of stormwater retention ponds is a rapidly growing area of interest, but there is a large gap in the literature with regard to validating the CFD models against experimental data for investigation of flow patterns and velocity distributions in stormwater retention ponds. This paper assesses a CFD model against experimental flow data from a laboratory scale physical model of an existing field retention pond. The simulated results were compared to each other and also to the experimental data to test the ability of numerical simulations for this type of problem. A representative and realistic range of flow rates from 0.16–1.5 l/s was tested in the physical model for comparison with the CFD model. Also, the vorticity from the physical model tests was compared to that from the numerical model to validate the CFD model. The results confirm previous findings that CFD modeling is a potential engineering tool to simulate hydraulics of stormwater retention ponds and can reliably be used in pond design even at moderate computational cost. Also, it was found that CFD is relatively insensitive to the turbulence model used and grid density within a wide range of grid densities for observing general flow patterns. However, it is sensitive to the advection schemes for this particular problem. Higher order differencing schemes (HRS) worked better than simple differencing schemes like the upwind differencing scheme (UDS). It was also found that the strength of the vorticity increases with increasing flow rate for both models and at higher flow rates CFD is more consistent in predicting the vorticity than that of the particle tracking velocimetry (PTV) technique used in physical models.

Select this Article		Temporal Variability of Bacterial Diversity in a Chlorinated Drinking Water Distribution System Stacia T. McCoy and Jeanne M. VanBriesen, M. ASCE Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000539 Posted ahead of print 19 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract The present work is the first to examine temporal variability of bacterial diversity in a free‐chlorinated drinking water distribution system over multiple years. We examined seasonal and monthly bacterial diversity using three different molecular methods. 16S rRNA gene clone library analysis identified the bacteria in Pittsburgh seasonal water samples, collected in fall 2006, and winter, spring, and summer 2007 and an event sample collected following a major pipe break, as primarily members of the alpha‐, beta‐, and gamma‐Proteobacteria classes, which agrees with previous studies of smaller numbers of bulk water samples over shorter durations. However, in this study, seasonal shifts in relative populations were observed with decreased alpha‐Proteobacteria and increased beta‐Proteobacteria diversity in the winter sample compared to the other seasonal samples, which may be due to changes in chlorine dosing. Further, in eleven monthly samples collected at the same location from September 2008 to August 2009, quantitative polymerase chain reaction (qPCR) results indicated that alpha‐ and beta‐Proteobacteria predominated over the year except for May and October, when changes in chlorine dosing due to temperature shifts may have influenced bacterial diversity. Denaturing gradient gel electrophoresis (DGGE) cluster analyses suggested that the monthly samples cluster seasonally with greater than 85% similarity between March and April, June and July, and December and January. These results demonstrate the consistent presence of alpha‐, beta‐, and gamma‐Proteobacteria in drinking water distribution systems across seasons during routine operational conditions and suggest that changes in bacterial class distributions may be useful indicators of system disruptions.

Select this Article		Municipal Wastewater Sludge Stabilization and Treatment Using Electrochemical Oxidation Technique Marc‐André Bureau, Patrick Drogui, Balasubramanian Sellamuthu, Jean François Blais, and Guy Mercier Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000538 Posted ahead of print 12 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract The objective of this research was to investigate the performance of an electrochemical process at the laboratory scale for enhancing dewaterability and stabilizing wastewater sludge from municipal wastewater treatment plant. This process encompasses advantages of simultaneous disinfection as well as odour removal from sludge. The process was composed of a 12 L‐cylindrical electrolytic cell containing Ti/RuO₂ anode and Ti cathode electrode. Current intensities varying from 5.0 to 10 A have been tested in the absence and the presence of electrolytes H₂SO₄ (10 to 27 kg/tDM) and NaCl (88 to 354 kg/tDM). The best performances for sludge treatment and stabilization were obtained while the electrolytic cell was operated during 60 min at a current intensity of 8.0 A, with energy consumption of 856 kWh/tDM and in the presence of 177 kg NaCl/tDM and 23.3 kg H₂SO₄/tDM. The electrochemical treatment induces particles agglomeration and enhances filterability of wastewater sludge during dewatering in the presence of a cationic polymer Percol 789 (2.5 kg/tDM). The process was efficient for increasing the dryness of sludge. A total solid gain of dehydrated sludge as high as 6 to 10 units were expected when the process was applied. The electrochemical process was also found to be effective in removing pathogen indicators (abatement > 4 – 5 log units of total and fecal coliforms) and unpleasant odours. At the same time, it preserved its fertilizing properties by maintaining the concentration of inorganic nutrients (P_tot and N‐NTK) and organic matter (COD) in dewatered sludge.

Select this Article		Factors Influencing Dissolved Copper Concentrations in Oregon Highway Stormwater Runoff Jeffrey A. Nason, Don J. Bloomquist, and Matthew S. Sprick Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000537 Posted ahead of print 12 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract Highway stormwater runoff represents a significant source of dissolved copper to surface waters. It is well established that even low concentrations of dissolved copper can be toxic to many aquatic organisms. In the Pacific Northwest of the United States, recent research has focused on the effects of low‐level copper exposure to salmonids listed as threatened or endangered under the Endangered Species Act (ESA). In light of these recent studies, increasingly stringent guidelines for the discharge of highway stormwater runoff have been imposed as part of ESA assessments of transportation projects. Assessing factors that may impact dissolved copper concentrations in stormwater provides a practical framework for predicting when and where copper toxicity could be problematic. A stormwater sampling effort was performed to examine the influence of site locale, traffic density, storm hydrology, the “first‐flush” effect, and water quality parameters on measured dissolved copper concentrations in highway stormwater runoff. In general, runoff from urban/high traffic sites and “first‐flush” samples exhibited higher copper concentrations than other samples. Increased dissolved copper concentrations were highly correlated with both dissolved organic carbon (DOC) and alkalinity. However, multiple linear regression modeling suggests that only the correlation with DOC has the potential to be causative. These findings will help inform State and Federal transportation and environmental protection agencies regarding the conditions under which elevated copper concentrations (and potential copper toxicity) are most likely to occur.

Select this Article		Optimised Treatment of Phenol‐Containing Fire Fighting Wastewater Using a Fenton Oxidation Diya'uddeen Basheer Hasan, A. R. Abdul Aziz, and Wan Mohd Ashri Wan Daud Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000536 Posted ahead of print 12 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract This study presents the degradation and mineralisation results of a phenol‐containing fire fighting wastewater (FWW) generated from quenching a fire outbreak in an oil storage facility. The chemical oxygen demand (COD) and phenol content of the wastewater were above the Malaysian Standard B discharge limits of 100 and 1 mg L⁻¹ for COD and phenol, respectively. The Fenton oxidation method was chosen as the treatment technique, and a response surface methodology was employed to optimise the response of the dependent variables: namely, COD, phenol and total organic carbon (TOC) percentage removals. Based on the wastewater COD, three controlling variables, namely, t_r and the mass ratios of [H₂O₂]:[FWW] and [H₂O₂]:[Fe²⁺], were studied at values of 0.5–8 h, 2–12 and 5–20, respectively. The results obtained for the treated samples showed complete phenol degradation. However, the optimum percentage of TOC and COD reduction were 53.4 and 77.5%, respectively. The low TOC removal was attributed to partial hydroxylation, which generated more aliphatic components that then retarded the mineralisation of the organic load. Kinetic studies using the Generalised Lumped Kinetic Model showed that the apparent kinetic constants, for the initial oxidation step (k′₁) and for the final oxidation step (k′₂), are 11.2 × 10⁻³ h⁻¹ and 6.4 × 10⁻³ h⁻¹, respectively. These results indicate that the reaction rate leading to the hydroxylation of the organic load is approximately twice as fast as the rate of intermediate product conversion to the final product. The fast initial rate (k′₁) accounted for the complete phenol degradation and the relatively slow second rate (k′₂) resulted in incomplete mineralisation of some of the intermediate organic by‐products.

Select this Article		UV Dose‐Response Behavior of Air‐Exposed Microorganisms Soojung Lim and Ernest R. Blatchley, III, M. ASCE, P.E., BCEE Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000535 Posted ahead of print 12 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract Laboratory experiments were performed to demonstrate an experimental method for measurement of UV dose‐response behavior among air‐exposed microorganisms, and to quantify the effect of relative humidity on this behavior. These experiments included two non‐pathogenic microorganisms as surrogates for airborne microbial pathogens: Bacillus subtilis spores and coliphage MS2. UV dose‐response behavior of these microorganisms was measured as a function of relative humidity (RH). Microorganisms were transferred to membrane filters at less than monolayer coverage and were subjected to exposure to UV radiation delivered from a collimated beam to a planar surface in a humidity‐controlled environment at two germicidally active wavelengths: 254 nm and 282 nm. Dose‐response data for Bacillus subtilis spores and coliphage MS2 exposed to UV radiation were fit to the Phenotypic Persistence and External Shielding (PPES) model. B. subtilis spores showed a modest effect of RH on the UV dose‐response behavior, whereas essentially no effect of RH was evident for air‐exposed MS2 in terms of their UV dose‐response behavior at 254 nm or 282 nm.

Select this Article		Enhancement of Ultraviolet Disinfection of Wastewater by Low Pressure Water Jet Pre‐Treatment: A Case Study of Effectiveness and Impacts on Bacteria Cheng He, Renée McFadyen, and Quintin Rochfort Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000534 Posted ahead of print 9 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract It has been proven that the concept of using a high pressure water jet (HPWJ) to pre‐treat wastewater for the enhancement of ultraviolet (UV) disinfection of wastewater is an effective and cost‐efficient alternative compared to the widely‐studied ultrasonic method. This study addresses: (1) the effectiveness of the pretreatment with a low pressure water jet (LPWJ) under similar experimental settings to the previous HPWJ study, (2) the water pressure impacts on bacteria in the treated wastewater and (3) the difference in electrical energy consumption under treatment with different pressures. The results show that with the tested primary clarifier overflow (PCO), there were no real differences in enhancement of UV disinfection with LPWJ pretreatment operating under a tested pressure range from 0.97 to 6.80 MPa. More than 1 log unit improvement of UV disinfection efficiency can be achieved under all the tested pressures compared to treatment by UV irradiation alone when the UV dose is in the 20 ∼ 30 mJ/cm² range. The general hypothesis for the enhancement of UV disinfection using a water jet is due to two factors: (1) reduction in the particle shield/shadow effects by breaking up the larger particles and (2) reduction in the resistance to UV irradiation by weakening the bacteria. Unfortunately, there is no easy and reliable way to test bacterial viability. In this study, an indirect method was proposed and corresponding experiments were conducted for an investigation of the impact of water jet force on the bacteria. Results show that for the tested pressure range from 0.97 to 6.80 MPa, there was no confirmation that the bacteria in PCO were weakened after being treated by the water jet. The main function of the water jet pretreatment was to affect a reduction of particle size in the treated water, instead of weakening the bacteria themselves.

Select this Article		Gas Pressure Model for Layered Municipal Solid Waste Landfills Yu‐Chao Li, Peter John Cleall, Xiao‐Fei Ma, Tony L. T. Zhan, and Yun‐Min Chen Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000533 Posted ahead of print 27 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract A mathematical model for calculating gas pressure profiles in layered landfill systems is presented. Solutions to scenarios considering a zero-pressure top boundary condition and a zero gas flux or fixed gas pressure bottom boundary condition are presented. Two cases, that is, specified gas pressure and specified inward gas flux, are addressed for scenarios having horizontal gas collection systems. A series of application examples demonstrate how the proposed model can be used to investigate the influences of i) variation of gas generation rate with respect to depth and time, ii) soil covers, iii) horizontal collection layers and iv) geomembrane and geosynthetic clay liner covers on gas pressure distribution in landfills. The proposed model provides a useful tool to landfill engineers in designing of landfill gas management systems and in particular when selecting and specifying gas collection system spacing and pumps.

Select this Article		Moisture Measurements as Performance Criteria for Extensive Living Roof Substrates Elizabeth Elizabeth, Ph.D. and Robyn Simcock, Ph.D. Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000532 Posted ahead of print 27 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract Extensive living roof substrate design to promote storm water management while balancing structural load and maintaining ≥ 60% non‐irrigated plant cover is investigated through linked laboratory and field experiments in Auckland, New Zealand. Setting quantifiable goals for FLL (2002) and agronomic testing methods resulted in successful design of multiple non‐proprietary substrates. Particle size distribution and quality control in the materials' supply chain are critical. Additional work is required to define a meaningful standard permeability test for living roofs. While the FLL (2002) maximum water capacity provides a conservative estimate for structural loading when a substrate is wet, it should not be used to predict storm water retention. Agronomic measures of readily available water (10–100 kPa suction) plus plant stress water (100–1500 kPa suction) provide a reasonable estimate for the maximum potential rainfall storage during individual storm events. Subject to Auckland's frequent rainfall, an extensive living roof with 70% v/v 4–10 mm pumice, 10% v/v 1–3 mm zeolite, and 20% organic matter at 100 mm depth is recommended to maintain plants without irrigation (excluding drought conditions) and minimize weeds while preventing runoff from storms with less than 25 mm rainfall.

Select this Article		Leaching of Metals from Fly Ash‐Amended Permeable Reactive Barriers Doina L. Morar, Ahmet H. Aydilek, M. ASCE, Eric A. Seagren, A.M. ASCE, and M. Melih Demirkan Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000531 Posted ahead of print 27 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract One beneficial reuse of high carbon content (HCC) fly ashes is in reactive barrier applications for remediation of contaminated groundwater. However, leaching of metals from the coal fly ashes into the environment is of concern. A series of column leach tests (CLTs) and batch water leach tests (WLTs) were performed to investigate the potential leaching of metals from HCC fly ashes during reactive barrier applications. Fly ash content and pH were two key factors affecting the leached amount in the WLTs. Leaching of metals in the CLTs exhibited a first‐flush, followed by a tailing elution pattern for all fly ashes. Attempts to correlate the WLT and CLT data indicated that scale up of the WLT results to the column experimental set‐up provided a better prediction of the leachable amount in CLTs compared to a direct comparison of concentrations. Nevertheless, caution should be exercised when building correlations because of the different testing conditions in the two test set‐ups.

Select this Article		Multivariate‐Parameter Optimization for Photodegradation of Tetracycline byFe(III)‐Citrate Complexes at Near Neutral pH Xiaonan Feng, Zongping Wang, Yong Chen, Tao Tao, and Feng Wu Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000530 Posted ahead of print 27 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract Tetracycline antibiotics have been extensively used in pharmaceutical and veterinary therapies, and they are widely present in natural waters. Although Fe(III)‐citrate complexes are known to be highly photoreactive, the optimal conditions for treatment of pollutants at near neutral pH are not fully understood. In this study, the photochemical removal of tetracycline (TC) in the Fe(III)‐citrate solution under simulated sunlight was investigated. A central composite design was employed to explore the effects of the initial concentrations of TC (0–90 μgM), Fe(III) (0–40 μM), citrate (0–400 μM) and pH (5.0–9.0) on the photodegradation of TC in aqueous solution. Five levels of each factor were included in the design. The photodegradation of TC in the Fe(III)‐citrate solution was observed to follow pseudo‐first‐order kinetics. According to the multivariate effects analysis, the optimal photodegradation condition was achieved at pH 6.9 and [Fe(III)]₀/[citrate]₀ = 33.8/324 (μM), with the corresponding rate constant 0.0323 min⁻¹ (t1/2 = 21.5 min). The quenching experiments verified that up to 74.5% degradation of TC was attributed to the attack of ^•OH formed in the Fe(III)‐citrate solution. The results indicated that Fe(III)‐citrate complexes were highly effective catalyst for the elimination of TC at near neutral pH under simulated sunlight.

Select this Article		Nitrate Reduction in Water Using Commercial Titanium Dioxide Photocatalysts (P25, P90, and Hombikat UV100) Kyle Doudrick, M.ASCE, Oihane Monzón, Alex Mangonon, Kiril Hristovski, Ph.D., and Paul Westerhoff, Ph.D., M.ASCE Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000529 Posted ahead of print 27 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract Photocatalytic nitrate reduction was examined in a model water and in groundwater by utilizing three commercially available titanium dioxide photocatalysts (Evonik P25, Evonik P90, and Sachtleben Hombikat UV100). The photocatalysts were characterized using uniform methods (TEM, XRD, surface area, UV‐VIS, surface charge) and their photocatalytic activity was differentiated using these results. Under all experimental conditions, P25 and P90 were superior to UV100, and P90 outperformed P25 with nitrate reductions as high as 77% at the maximum irradiance level used (6.46 × 10²² photons/L). The photocatalytic nitrate reduction activity was found to be dependent upon the rate of recombination, pH, and total photocatalyst surface area, with the recombination rate being the limiting variable. Nitrate reduction was more efficient in model water than in groundwater that contained constituents capable of occupying photocatalyst surface sorption sites or scavenging conduction band electrons. The greater efficiencies of P25 and P90 compared to UV100 were attributed primarily to the mixed‐phase nature of the photocatalysts, which allow for better charge separation, and the greater activity of P90 over P25 was attributed to a larger surface area. The results should be helpful in the selection of these commercially available photocatalysts to treat a wide range of pollutants other than nitrate.

Select this Article		Contaminant Mass Transfer from NAPLs to Water Studied in a Continuously Stirred Flow Through Reactor Lihua Liu, Uli Maier, Peter Grathwohl, and Stefan Haderlein Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000528 Posted ahead of print 27 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract The release of NAPLs from porous media to groundwater is a widespread environmental problem. The mass transfer of individual NAPL components controls both the extent of groundwater contamination and the persistence of the residual NAPL phase. In order to quantify this key process, small‐scale experimental studies on NAPL‐water mass transfer were performed in a dynamic system mimicking environmental conditions with “clean” water continuously flowing through the NAPL pool. To describe this process a modified simulation method was developed and validated by the experimental data. The experimental system consisted of a custom designed flow cell (with NAPL and water) connected to the peripheral equipment (pump, water source etc.). This continuously stirred flow through reactor was used to perform mass transfer experiments with simple and complex model NAPL‐water systems. To simulate the experimental data (concentration vs. time profiles of individual NAPL compounds) an analytical solution of a standard mass transfer model was adapted in simple model NAPL systems, and a numerical method was employed for complex multi component model NAPL‐water systems containing phenols, heteroaromatic compounds and PAHs. The numerical model was developed based on a mass balance equation and a general form of Raoult's law. The simulated concentration profiles of the various solutes matched well the experimental data only if the non‐ideal behavior of the more polar solutes was accounted for. Using the developed numerical mode simulated mass transfer coefficients for individual NAPL components compared well with previously published values if available.

Select this Article		Flocculation, Ozonation and Fenton's Process in the Treatment of Distillery Effluents Rui C. Martins, Fábio L. Pinto, Sérgio Castro‐Silva, and Rosa M. Quinta‐Ferreira Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000527 Posted ahead of print 23 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract This paper reports the application of flocculation, Fenton's process and ozonation on the depuration of distilleries wastewaters. The treatment processes were analysed separately; nevertheless, integration schemes were also considered. The commercial flocculant 923PWG lead to up to 84% of TSS removal even if a very low COD abatement was observed (<2%). The effect of hydrogen peroxide concentration and [H₂O₂]/[Fe²⁺] molar ratio were tested on Fenton's process efficiency. Moreover, the [H₂O₂] injection mode was still analysed. Gathering up both COD degradation and biodegradability enhancement it was possible to selected the following operating conditions [[H₂O₂]] = 0.5 M and [[H₂O₂]]/[Fe²⁺] = 10 (mol/mol), being the oxidant totally introduced at the beginning of the reaction. Ozonation showed poor results regarding organic matter removal; however, it seems to be an interesting methodology raising the effluent's BOD5/COD ratio. In fact, in the strategies involving the integration of ozonation with Fenton's process it was possible to conclude that ozone oxidation did not improved COD degradation; nonetheless it was essential to improve biodegradability. Particularly conducting ozonation (at pH=3) after Fenton's revealed to be an interesting approach leading to an effluent amenable to further biodegradation.

Select this Article		An Alternative Approach to Evaluate Sedimentation Performance of Stormwater Detention Basins Using A Nondimensionalized Time Scale Masatsugu Takamatsu, M.ASCE, Michael E. Barrett, and Randall J. Charbeneau Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000526 Posted ahead of print 21 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract To evaluate sediment removal in dry detention basins, one of the most frequently used Best Management Practices (BMPs), a particle pathline model using plug flow assumption was proposed in a previous study. The model requires numerical integration, thus it may not be convenient for quick evaluation and design of detention basins. To overcome the difficulty a simpler CSTR model is proposed and used to compare outflow Suspended Sediment Concentrations (SSCs) from different size storms using a nondimensionalized time scale. The CSTR model satisfactorily predicts sediment removal and outflow SSC measured using a physical model. The paper presents the time nondimensionalization and CSTR model application processes; and discusses the critical characteristics of the proposed models.

Select this Article		The effects of ozonation and catalytic ozonation on the removal of natural organic matter from groundwater Jelena Molnar, Jasmina Agbaba, Božo Dalmacija, Mile Klašnja, Malcolm Watson, and Marijana Kragulj Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000525 Posted ahead of print 21 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract This investigation compares the effects of ozonation (0.4 to 3.0 mg O3/mg DOC) and TiO₂‐catalyzed ozonation ‐ TiO₂‐O₃ (0.4 to 3.0 mg O₃/mg DOC; 1.0 mg TiO₂/L) at pH 7.46 on the removal of natural organic matter (NOM) from groundwater from the Central Banat (Northern Serbia) region. This groundwater is rich in NOM (9.85 mg/L DOC), which are mostly of hydrophobic character (65% fulvic acid and 14% humic acid fraction). Ozonation and TiO₂‐O₃ resulted in almost identical degrees of DOC content reduction (up to 30%), with the maximum efficacy of both processes being achieved with 3.0 mg O₃/mg DOC. The application of oxidation treatments resulted in complete humic acid oxidation, and increased the content of the hydrophilic fraction (up to 72%). The use of TiO₂‐O₃ did not result in an improvement in the removal of trihalomethane precursors in comparison to ozonation (up to 48%), but produced less brominated species, while using the TiO₂‐O₃ process resulted in better removal of haloacetonitrile precursors (up to 44% removal) than ozonation, which had less effect.

Select this Article		Application of Kalman Filter with Time Correlated Measurement Errors in Subsurface Contaminant Transport Modeling Shoou‐Yuh Chang, M.ASCE, Godfrey Mills, and Sikdar Latif Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000524 Posted ahead of print 21 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract Prediction of a conservative solute transport in the subsurface is investigated by applying a Kalman filter (KF) that uses time correlated error and a KF that uses Gaussian error. The observation data generated from an analytical solution of two dimensional advection dispersion equation with an additive time correlated random errors were used as the measurement equation for the KF with time correlated measurement errors and the KF with white Gaussian errors. The measurement differencing algorithm was adopted in deriving a discrete time varying KF with time correlated measurement errors for predicting contaminant transport in the subsurface in the case of observations with time correlated errors. Simulation results indicated an improved root mean square error (RMSE) profile of KF with time correlated errors over KF with white Gaussian error. The KF with time correlated error reduced the error in the prediction by 11.4% when compared to the KF with white Gaussian error. The stability analysis of the two filters indicated that both filters were stable and convergent for the entire simulation duration.

Select this Article		Evaluating the Relationships between Pb Species and Leaching Properties in Simulated MSWI Fly Ash with Thermal Treatment by ESCA Jing‐Dong Chou, Shih‐Hsien Chang, Chiou‐Liang Lin, Jia‐Hong Kuo, and Ming‐Yen Wey Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000522 Posted ahead of print 19 November 2011 Full Text: \| Download PDF
	+ -	Show Abstract The aim of this study was to develop a fundamental understanding of the association between Pb species and leachability behavior during the thermal treatment process. Two main factors that influence this process, temperature and the carbon content in the simulated ash, were also studied. In the sequential extraction results, the main distribution pattern of Pb in treated simulated ash was carbonate fraction with different temperatures when carbon content was 3.5%. The chief fraction of raw simulated ash (carbon content = 0%) was carbonate, and that of raw simulated ash was Fe‐Mn oxide when carbon content increased. Electron spectroscopy for chemical analysis (ESCA) results showed that Pb (element) in treated simulated ash could increase the TCLP concentration of Pb when temperatures reached 700 °C. With a temperature of 900 °C, PbSiO₃ was present in treated simulated ash and reduced the TCLP concentration of Pb. A comparison of different carbon contents showed that PbO‐SiO₂‐related compounds were present in raw simulated ash and caused the distribution patterns of Pb to become stable as carbon content was increased.

Select this Article		The Need for and Use of High Resolution Turbidity Monitoring in Managing Discolouration in Distribution John W. Gaffney and Stephen Boult Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000521 Posted ahead of print 17 November 2011 Full Text: \| Download PDF
	+ -	Show Abstract Turbidity measurements at high temporal resolution from several sites within the distribution network gave a more complete record of the variability of turbidity than previously possible, showing that there are frequent movements of sediment at low concentration. Knowledge of the availability of sediment was shown to be important to prediction of turbidity, as the correlation of hydraulic disturbance (indicated by pressure change) alone with changes in turbidity was weak. These datasets also showed with greater confidence than previously possible that mains flushing frequently resulted in incomplete removal of sediment. Given that knowledge of sediment availability is required to reduce uncertainty in prediction of turbidity, measurements at high temporal and spatial resolution were used to calculate sediment mass balances and determine its distribution within the study area. A net accumulation of 0.923kg of sediment was observed within 2482m of main, equivalent to 5.212 g m⁻¹y⁻¹; it was also possible to identify the impact of hydraulic disturbance in changing sediment sinks to sources during the monitored period. In addition the sediment fluxes gave some insight into the processes of deposition and resuspension. The former was shown to be unaffected by sediment concentration and an increase in the latter was seen to persist for several days following a hydraulic disturbance of < 15 minutes. High resolution monitoring may be useful for improving the targeting and evaluation of current reactive maintenance strategies for reducing discolouration and may also form the basis of more proactive strategies. The latter may be possible by using sediment budgets in conjunction with operational intervention to actuate mild hydraulic disturbances to encourage sediment throughput and maintain the discolouration risk below a critical limit.

Select this Article		Use of Frequency and Duration Analysis for the Determination of Thermal Habitat Thresholds: Application for the Conservation of Alasmidonta heterodon in the Delaware River, USA Elena Castelli, Piotr Parasiewicz, and Joseph N. Rogers Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000520 Posted ahead of print 12 November 2011 Full Text: \| Download PDF
	+ -	Show Abstract A novel approach for setting thermal habitat recommendations for an endangered aquatic species will be proposed in this paper. The method, Uniform Continuous Above Threshold (UCAT) analysis, evaluates the duration and frequency of continuous events where the temperature is higher than a specified value and identifies temperature levels that, because of their rare occurrence in the past, can be considered stressor thresholds. The UCAT analysis was applied to set thermal habitat recommendations for Alasmidonta heterodon, an endangered mussel species in the Upper Delaware River. We found that a maximum daily water temperature of 26.5°C lasting for more than 7 days is a rare event in the A. heterodon population centers in Upper Delaware River and consequently this condition should be avoided by adjusting already regulated cold‐water releases from upstream reservoirs. Knowledge of temperature thresholds and their relationship with persistent low‐flow periods provided further decision support for the development of flow management recommendations for species protection. The case study of A. heterodon in the Upper Delaware River demonstrates that, in the absence of laboratory research on physiological temperature tolerance of a species, UCAT analysis provides an effective way to approximate habitat conditions that fall within thermal tolerances. Due to quick and easy preparation and analysis this method may also have a broader application to habitat studies of other animal groups.

Select this Article		Absorption Behavior and Removal of Gaseous Elemental Mercury by Sodium Chlorite Solutions Yi Zhao, Jie Yao, and Xiao‐ying Ma Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000519 Posted ahead of print 10 November 2011 Full Text: \| Download PDF
	+ -	Show Abstract The absorption behavior of Hg⁰ was studied experimentally by using sodium chlorite (NaClO₂) as the absorbent in a bubble reactor. Primary influencing factors on removal of Hg⁰ such as NaClO₂ solution concentration, solution pH, reaction temperature, the concentration of Hg⁰ and other components in the flue gas, such as O₂, SO₂ and NO were investigated. Approximately sixty five percent removal of elemental mercury can be achieved under optimal experimental conditions. The removal mechanism of Hg⁰ was proposed by analyzing of Hg²⁺ concentration in the spent absorption solution and comparing the electrode potentials between NaClO₂ species and Hg²⁺/Hg⁰.

Select this Article		Use of Long‐Term Monitoring Data to Evaluate Benzene, MTBE and TBA Plume Behavior in Groundwater at Retail Gasoline Sites R. Kamath, J. A. Connor, T. E. McHugh, A. Nemir, M. P. Le, and A. J. Ryan Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000488 Posted ahead of print 4 November 2011 Full Text: \| Download PDF
	+ -	Show Abstract Long‐term groundwater monitoring data for 48 retail gasoline sites have been analyzed to define the characteristics of affected groundwater plumes containing benzene, methyl tert‐butyl ether (MTBE), and tert‐butyl alcohol (TBA). Results of this analysis have been used to determine the observed range and statistical distribution of current plume lengths, plume stability conditions, constituent concentration trends and attenuation rates, and the remediation timeframe for this population of sites. The goal of this evaluation has been to characterize plume behavior as observed across a variety of hydrogeologic settings, based upon detailed groundwater monitoring records, rather than to define the site‐specific factors controlling plume behavior. The results indicate that MTBE plumes in groundwater underlying a majority of these UST sites that have been monitored for 5 years or more: i) have significantly diminished in concentration over time, ii) are comparable in length to benzene plumes, iii) are, like benzene plumes, principally stable or shrinking in size and concentration, and iv) are on track to achieve remedial goals within a timeframe comparable to or faster than that of benzene plumes. At these same sites, TBA plumes were found to be comparable to benzene and MTBE plumes in terms of plume length. However, while most TBA plumes are also stable or shrinking, the percentage of TBA plumes that are currently stable or shrinking (68%) is less than that for benzene plumes (95%) or MTBE plumes (90%), likely reflecting the temporary build‐up of TBA concentrations in groundwater due to MTBE biodegradation. Nevertheless, overall trends for TBA concentrations in groundwater indicate that TBA is attenuating at rates comparable to benzene and MTBE and can be expected to meet applicable remediation goals in a similar timeframe as the other gasoline constituents.

Select this Article		Performance of Modified Electro‐Fenton Process for Phenol Degradation Using Bipolar Graphite Electrodes and Activated Carbon Chunping Yang, Huanyu Liu, Shenglian Luo, Xiong Chen, and Huijun He Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000517 Posted ahead of print 3 November 2011 Full Text: \| Download PDF
	+ -	Show Abstract A modified version of the electro‐Fenton process was evaluated for the degradation of phenol in an aqueous solution with bipolar graphite electrodes and activated carbon. The effects on reaction parameters including pH value of the solution, the dosage of ferrous ion, and the current density within the solution on the removal of phenol and COD_Cr at various reaction time were evaluated for the treatment of wastewater containing phenol of 100 mg/L and granular activated carbon (GAC) of 333 g/L at 25±1°C. Removal mechanisms were also investigated by analyzing intermediate products using HPLC and GC‐MS. Results showed that removal efficiencies of phenol and COD_Cr were 93% and 65% respectively at pH of 3.0, a current density of 3.75 mA/cm², a dosage of ferrous ion of 0.10 mmol/L, and a reaction duration of 60 min. When reaction time was increased to 180 min, phenol concentration in the wastewater was below detection limit. Phenol removal efficiency decreased significantly when Na₂CO₃, a hydroxide radical scavenger, was added in the reactor. This indicates that both electro catalytic oxidation and radical oxidation contributed to the degradation of phenol. The removal efficiency of phenol achieved 39%, 65%, and 93% at a reaction time of 60 min when the traditional electrolysis, the traditional electro‐Fenton process, and the modified electro‐Fenton process were used, respectively.

Select this Article		Effectiveness of “LID” for Commercial Development in NC D. E. Line, R. A. Brown, W. F. Hunt, and W. G. Lord Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000515 Posted ahead of print 20 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract The purpose of this project was to characterize runoff and pollutant export from three commercial sites: one with no stormwater control measures (NoTreat), one with a wet detention basin (WetBasin), and one with Low Impact Development (LID) measures. The sites were located in the Piedmont and Coastal Plain physiographic regions of central North Carolina. Rainfall, runoff, and pollutant concentrations were monitored at each site for more than one year using automated raingages and samplers. The storm event mean concentrations (EMCs) of total kjeldahl nitrogen (TKN), nitrate+nitrite nitrogen (NO_xN), and total phosphorus (TP) in runoff were generally less than corresponding EMCs for many other urban areas in the U.S. Also, EMCs were similar to those found for 8 parking lots in North Carolina. Storm runoff to rainfall ratio was greatest for the NoTreat site and least for the WetBasin site, which was anticipated because the NoTreat site had no detention/storage and the WetBasin site had the greatest detention/storage. Export of TKN, ammonia nitrogen (NH₃N), TP, and total suspended solids (TSS) was lowest for the LID site, while export of NO_xN and TN was lowest for the WetBasin site. While by no means definitive, the monitoring data indicated that the LID site with its multiple LID measures, was more effective at reducing export for most pollutants than the WetBasin site with its wet detention basin.

Select this Article		Simulation of Countercurrent Operation of Two‐Stage Hybrid PAC‐Submerged Membrane System for Trace Organics Removal Yue Jia, Rong Wang, and Anthony G. Fane Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000514 Posted ahead of print 18 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract A countercurrent two‐stage hybrid powdered activated carbon‐submerged membrane (PAC‐SM) system for atrazine removal has been simulated numerically in the present work. The simulation of the system performance at different operating conditions confirms that the adsorption capacity of the PAC can be further utilized and a stable product water quality can be maintained in the countercurrent two‐stage mode as compared to the concurrent single‐stage operations. For instance, the utilization of the PAC adsorption capacity was enhanced by 28% in the countercurrent two‐stage operation at a flux of 60L/m²h, and 21% of enhancement was obtained at a flux of 100L/m²h by more frequent PAC replacement. Therefore, the adsorption capacity utilization is also dependent on the membrane filtration flux. Moreover, if the final effluent concentration was controlled at a higher level (e.g. C₂^∗ = 0.1 instead of C₂^∗ = 0.05), a further 5% of the PAC adsorption capacity can be utilized. In addition, reducing the replacement rate (RR) will make the operation similar to a system with continuous PAC dosing (‘pseudo‐steady state’) by presenting nearly constant product water quality. This study sheds some light on the performance of a countercurrent multi‐stage hybrid PAC‐SM system for its further applications and system optimization.

Select this Article		Framework to Determine the Optimal Spatial Location and Number of Municipal Solid Waste Bins in a Developing World Urban Neighborhood Adeniyi S. Aremu, B. F. Sule, Joni Downs, and James R. Mihelcic Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000513 Posted ahead of print 15 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Determining the optimal location and quantity of waste bins for the collection of municipal solid wastes is challenging because it influences service coverage and public satisfaction, and is often influenced by economic and environmental constraints. This study develops a framework that applies a Geographic Information System for siting municipal waste bins and determines the optimum quantity of waste bins using Analytic Hierarchy Process. The framework was applied to a neighborhood in a developing world city (Ilorin, Nigeria). The spatial performance of specific quantities of waste bins was evaluated for social, economic and environmental impacts, as determined from p‐median solutions using field collected solid waste generation data and operational data for the collection vehicles. For the study site, the most optimal solution is five waste bins whose spatial location utilized their capacities and produced less comparative negative impacts. The result represents a starting point for extension to larger urban areas by considering the smallest basic unit for spatial and multi‐criteria analysis. The approach is promising for improvement of municipal solid waste management in developing world cities.

Select this Article		Can Surface Overflow Rate Predict Particulate Matter Load Capture for Common Urban Drainage Appurtenances? A. Bolognesi, A. Ciccarello, M. Maglionico, J. ‐Y. Kim, S. Artina, and J. Sansalone Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000512 Posted ahead of print 15 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Urban drainage appurtenances separate particulate matter (PM) and detritus whether by design or unintentionally. Such PM separation impacts conveyance, treatment and maintenance practices. This study examines two common appurtenances; gully pots (or catch basins) and screened hydrodynamic separators (HS). Under steady and controlled physical model testing, PM separation was measured for influent granulometry (particle size distributions, PSDs, PM specific gravity). Catch basin separation ranged from 40 to 99% for a mono‐disperse (well‐graded sand, SW) PSD and 60 to 83% for a hetero‐disperse PSD. With similar testing the HS was also loaded with a hetero‐disperse sandy silt (ML) and tested as a function of flow, with separation of 40 to 65% as compared to 70 to 99% for the SW, similar to the catch basin. Physical model results were compared to surface overflow rate (SOR) model illustrating SOR overestimated PM separation by 3 to 13%. SOR was extended to unsteady runoff events. For unsteady loading of an HS with complex hydrodynamics and short residence times, SOR over‐predicted measured PM separation by 3 to 22% based on PM granulometry. For maintenance and coarse PM load inventories, SOR can reasonably predict coarse PM fate subject to Type I settling in an HS and catch basin, units with similar PM separation behavior. If suspended PM mass dominates the PSD or is a treatment objective, or for units with long residence times, the continuous phase hydrodynamics must be coupled with a discrete phase model, requiring analytical or numerical models such as CFD. For conditions illustrated herein SOR is robust.

Select this Article		Modeling of Dissolved Oxygen Concentration Using Different Neural Network Techniques in Foundation Creek, El Paso County, Colorado, USA Murat Ay and Ozgur Kisi Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000511 Posted ahead of print 15 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract The aim of this study is to examine the accuracy of two different artificial neural network (ANN) techniques, the multi‐layer perceptron (MLP) and radial basis neural network (RBNN), to estimate dissolved oxygen (DO) concentration. The ANN results are compared with multi‐linear regression (MLR) model. The neural network model is developed using experimental data collected from the upstream (USGS Station No: 07105530) and downstream (USGS Station No: 07106000) stations on Foundation Creek, Colorado. The input variables used for the ANN models are water pH, temperature, electrical conductivity, and discharge. The determination coefficient (R²), mean absolute error (MAE), and root mean square error (RMSE) statistics are used for the evaluation of the applied models. The MLP and RBNN models are also compared with MLR model in estimating the DO of the downstream station by using the input parameters of the upstream station. Comparison results indicate that the RBNN model performs better than the MLP and MLR models.

Select this Article		Estimated Trophic State Effects and Abatement Costs in Connection with Improved Urban Sewage Treatment in the Gulf of Riga Andreas C. Bryhn Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000510 Posted ahead of print 15 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Environmental conflicts of interest are important to account for when environmental policies are designed. This paper explores the quantitative connection between urban waste water treatment, coastal eutrophication, and fish biomass in the mesotrophic Gulf of Riga (northern Europe). The probable effect on the water quality from one clearly defined abatement measure, improved urban sewage treatment has been studied. Furthermore, the implementation cost and the likely effect on total fish biomass have also been assessed. Computer simulations using the previously published model CoastMab suggested that good water quality according to the EU Marine Strategy Framework Directive could be achieved if urban sewage treatment would be upgraded to Nordic and German standards, and not only around the Gulf of Riga but in the whole Baltic Sea drainage basin. The Secchi depth would double according to these simulations while total phosphorus and summer chlorophyll concentrations would decrease by 54% and 53%, respectively. The total fish biomass should be expected to decrease by about 42% if “good” water quality (as defined in European Union directives) should be achieved. However, changes in total fish biomass could also be offset by changes in other important determinants such as climate related variables or fishing pressure. The study estimated that it could take about 20–40 years after abatement action for the trophic state in the Gulf to stabilise again. Upgrading urban sewage treatment to this extent would cost 468–1,118 million euros per year. Treatment could have substantial positive effects on the water quality of the Gulf but could also have adverse side effects on the total fish biomass.

Select this Article		LID Treatment Train: Pervious Concrete with Subsurface Storage in Series with Bioretention and Care with Seasonal High Water Tables R. A. Brown, D. E. Line, and W. F. Hunt Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000506 Posted ahead of print 14 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Two infiltrating low impact development (LID) practices configured in series, pervious concrete and bioretention (PC‐B), were monitored for 17 months to examine the hydrologic and water quality response of this LID treatment train design. For the first LID practice, 0.53 ha of pervious concrete was installed to treat direct rainfall and run‐on from 0.36 ha of asphalt parking lot. The pervious concrete was installed over a gravel subsurface storage basin, which was designed to store 25 mm (1 in) of runoff from the parking lot before draining into the second LID practice — a 0.05 ha bioretention cell. The bioretention cell was conventionally drained, had a media depth of 0.5 m (1.6 ft), and was constructed at a location with a high water table. Outflow was only generated in 33 out of 80 monitored events, and over the course of the entire monitoring period, the total outflow volume reduction was 69 percent. The large outflow reduction subsequently led to high pollutant load reductions for total nitrogen (49%), total phosphorus (51%), and total suspended solids (89%). However, when the contribution of baseflow was included in the calculation, the total nitrogen load discharged from the bioretention cell was 64% higher than that of the runoff load because of nitrite and nitrate (NO_2,3‐N) present in the baseflow. The total nitrogen (TN) loads of runoff, storm flow (total outflow minus baseflow), baseflow, and outflow (total) were 7.70, 3.94, 8.69, and 12.64 kg/ha/yr, respectively. Of the 8.69 kg/ha/yr TN in the baseflow, 92 percent was in the form of NO_2,3‐N. This study demonstrated the hydrologic benefits (peak flow and outflow reduction) gained by having two infiltration LID practices in series. When compared to a single treatment practice (bioretention) that was monitored at the same site, the LID practices in series treated an additional ten percent of annual runoff volume, discharged approximately one‐half as much outflow volume, and discharged significantly lower peak outflow rates. However, the water quality results were not as promising due to the influx of groundwater in the bioretention cell and the lack of denitrifying conditions in either the bioretention cell or pervious concrete system. This study also quantified increased TN and NO_2,3‐N export to surface waters from a bioretention cell that was sited in an area with a high water table.

Select this Article		Meeting Hydrologic and Water Quality Goals through Targeted Bioretention Design William F. Hunt, Allen P. Davis, and Robert G. Traver Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000504 Posted ahead of print 8 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Bioretention is one of the most commonly used stormwater control measures (SCMs) in North America and Australasia. However, current design is not targeted to the regulatory need, often reflecting an outdated understanding of how and why bioretention works. The purpose of this manuscript is to synthesize research to recommend a suite of design standards focused on the purpose of the bioretention SCM. Both hydrologic (peak flow mitigation, infiltration, annual hydrology, and stream stability) and water quality (TSS and particulates, pathogen indicator species, metals, hydrocarbons, phosphorus, nitrogen, and temperature) regulatory and stream ecology needs are addressed. Bioretention cells designed to meet a prioritized subset of those measures would be substantially different than cells that are designed for a different needs subset. Designers have the ability to adjust bowl volume, media composition, media depth, underdrainage configuration, and vegetation type. This study examines how each of those design parameters can be adjusted so that a “one size fits all” approach is no longer the norm.

Select this Article		The Dynamic Response of Sulfate‐Reducing and Methanogenic Activities of Anaerobic Sewer Biofilms to Ferric Dosing Lishan Zhang, Nicolas Derlon, Jürg Keller, and Zhiguo Yuan Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000481 Posted ahead of print 2 September 2011 Full Text: \| Download PDF
	+ -	Show Abstract A recent study showed that, in addition to precipitating sulfides, Fe³⁺ addition to sewers reduces the sulfate‐reducing and methanogenic activities of anaerobic sewer biofilms. The dynamic response of these activities to the commencement and termination of ferric dosage is investigated in this study. Both the sulfate reduction and methane production rates of anaerobic sewer biofilms decreased upon the addition of ferric ions, with a maximum inhibition of approximately 50% achieved after 3 and 7 days, respectively. In comparison, the sulfate‐reducing activity of suspended biomass in the Fe³⁺ receiving reactor was completely inhibited. The volatile solids to total solids (VS/TS) ratio of sewer biofilms decreased from 91±3% prior to Fe³⁺ addition to 54±6% after a full adaptation of the biofilms to Fe³⁺ addition. Energy Dispersive Spectroscopy profiles showed higher iron and sulfur contents in biofilms adapted to Fe³⁺ addition, suggesting FeS deposition in biofilms. We hypothesise that FeS precipitation primarily occurred on the upper layer of sewer biofilms causing inhibition to sulfate‐reducing bacteria (SRB) and methanogenic archaea (MA) in this layer (and in the suspended phase). However, SRB and MA were likely to be active in the deep layer. The sulfate‐reducing activity recovered to approximately 90% that of the reference reactor in five weeks after Fe³⁺ injection was stopped, while there was no recovery of the methanogenic activity in the same period. The results suggest that a temporary suspension of ferric dosage would not lead to immediate recovery of the sulfate‐reducing and methanogenic activities. The recovery of sulfate‐reducing activity was found to be linearly correlated with the recovery of biofilm VS/TS ratio, following the termination of Fe³⁺ addition.

Select this Article		Effect of Dispersant on Transport of Nanoscale Iron Particles in Soils: Zeta Potential Measurements and Column Experiments Claudio Cameselle, Krishna R. Reddy, Kenneth Darko‐Kagya, and Amid Khodadoust Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000473 Posted ahead of print 30 July 2011 Full Text: \| Download PDF
	+ -	Show Abstract Nanoscale iron particles (NIP) have been studied during the last few years for their potential for remediation of groundwater and soils contaminated by chlorinated hydrocarbons, pesticides, heavy metals and some inorganic anions. However, the effectiveness of in situ remediation largely depends on quick and uniform distribution of NIP into the contaminated subsurface zones. Previous studies have shown that transport of bare NIP in subsurface soils is very limited and surface modification by dispersants such as polymers and surfactants is necessary. The objective of this study was to investigate eight different dispersants at different concentrations to determine their ability to modify the surface characteristics and increase the stability of the NIP suspension, thereby minimizing agglomeration and sedimentation of the NIP. The studied dispersants and their tested concentration ranges (as % of NIP suspension, w/w) were: aluminum lactate (2–15%), sodium lactate (6–12%), ethyl lactate (6–12%), aspartic acid (2–8%), polyacrylic acid (2–8%), 2‐hydroxypropil‐β‐cyclodextrin (1–4%), β‐ cyclodextrin (1–4%) and methyl‐cyclodextrin (1–4%). Zeta potential measurements and column experiments were performed on NIP‐dispersant suspensions. Results showed that the zeta potential of bare NIP was 41.7±2.3 mV. The influence of the dispersants was found to vary significantly depending on the chemical nature of the dispersant and the electrical charge of the ions in solution. Aluminum lactate released Al³⁺ into the solution, resulting in a reduction of the NIP zeta potential from 37.7±1.8 mV at 2% concentration to 9.5±0.7 mV at 15% concentration. Finally, cyclodextrins showed less influence on the zeta potential of NIP with a slight increase (up to 49.3±3.2 mV). The results depict that higher percentage of NIP modified with aluminum lactate eluted from the soil. 10% aluminum lactate exhibited the highest (93%) elution of the modified iron from the soil media. Aspartic acid and ethyl lactate showed less amount of iron eluted (35–40%). The column tests demonstrated that aluminum or sodium lactate can increase the stability of NIP suspension as well as enhance their transport in subsurface soils. Furthermore, these dispersants are environmentally‐friendly, relatively inexpensive, and practical to use.

Select this Article		Integrated Modeling for Optimal Strategies under Uncertainty ‐ A Case Study of Municipal Solid Waste Management Y. P. Li and G. H. Huang Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000393 Posted ahead of print 12 March 2011 Full Text: \| Download PDF
	+ -	Show Abstract In this study, an inexact fuzzy‐probabilistic programming (IFPP) method is advanced for developing optimal municipal solid waste (MSW) management strategy with uncertain information. The IFPP can support the assessment of risk of violating constraints associated with fuzzy and random features. The developed method is applied to a case study of long‐term MSW management planning in the City of Changchun, China. Violations for transfer‐station capacity constraints are allowed under a range of probability and possibility levels, which are related to tradeoffs between the system cost and the constraint‐violation risk. The results indicate that useful solutions for planning the MSW management practices have been generated. They are valuable for supporting the identification of efficient waste‐flow allocation patterns, the long‐term capacity planning of the city's waste management system, and the formulation of local policies regarding waste management under uncertainty.

Select this Article		Effect of Reaction Temperature on CO₂ Capture Using a Potassium‐Based Solid Sorbent in a Bubbling Fluidized‐Bed Reactor Yongwon Seo, Sung‐Ho Jo, Chong Kul Ryu, and Chang‐Keun Yi Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000001 Posted ahead of print 20 February 2009 Full Text: \| Download PDF
	+ -	Show Abstract We investigated the effects of carbonation and regeneration temperature on the CO₂ capture characteristics using SorbKX35, a potassium‐based solid sorbent in a bubbling fluidized‐bed reactor. A dry sorbent, SorbKX35 consists of K₂CO₃ for absorption and supporters for mechanical strength. We also measured the physical properties of the sorbent, such as pore size, pore volume, and surface area after carbonation or regeneration, to confirm the extent of the reaction. With H₂O vapor pretreatment, nearly complete CO₂ removal was initially achieved and maintained for about 10 min within a temperature range of 333.15 – 363.15 K with 2 s gas residence time. At lower temperature, CO₂ capture was more effective during 1 h of carbonation. From the results of temperature programmed desorption (TPD) and gas adsorption method (BET), we found that the regeneration of carbonated SorbKX35 was not complete at 473.15 K. The results obtained in this study can be used as basic data for designing and operating a large scale CO₂ capture process with two fluidized‐bed reactors.

Select this Article		Removal of Zn²⁺ from Electroplating Wastewater Using Modified Wood Sawdust and Sugarcane Bagasse Flaviane V. Pereira, Leandro V. A. Gurgel, Sérgio F. de Aquino, and Laurent F. Gil Journal of Environmental Engineering doi:http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000011 Posted ahead of print 20 February 2009 Full Text: \| Download PDF
	+ -	Show Abstract This work describes the preparation of new adsorbents derived from sugarcane bagasse and wood sawdust (Manilkara sp.) to remove zinc (II) ions from electroplating wastewater. The first part deals with the chemical modification of sugarcane bagasse and wood sawdust, using succinic anhydride to introduce carboxylic acid functions into the material. The obtained materials (modified sugarcane bagasse MB2 and modified wood sawdust MS2) were then characterized by infrared spectroscopy (IR) and used in adsorption experiments. The adsorption experiments evaluates Zn²⁺ removal from aqueous single metal solution and real electroplating wastewater on both batch and continuous experiments using fixed‐bed columns prepared in laboratorial scale with the obtained adsorbents. Adsorption isotherms were then developed using Langmuir model and the Thomas kinetic model. The calculated Zn²⁺ adsorption capacities were found to be 145 mg/g for MS2 and 125 mg/g for MB2 in single metal aqueous solution, whilst for the industrial wastewater these values were 61 mg/g for MS2 and 55 mg/g for MB2.