Water Environment Research (WATER ENVIRON RES)

Publications in this journal

• Article: Effects of microwave irradiation on dewaterability and extracellular polymeric substances of waste activated sludge.

  Ge Peng, Fenxia Ye, Yangfang Ye
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  ABSTRACT: The effects of microwave irradiation on filterability and dewaterability of waste activated sludge measured by capillary suction time (CST) and dry solids in sludge cake were investigated. The results showed that the optimum irradiation time improved filterability, but that further increase of the time was detrimental. Dewaterability was enhanced significantly and increased with microwave time. Filterability and dewaterability were improved 25 to 28% and 1.3 times at the optimum times of 30 and 90 seconds for the sludge of 5 g total suspended solids (TSS)/L and 7 g TSS/L, respectively. The floc size decreased slightly. Loosely bound extracellular polymeric substances (LB-EPS) decreased under optimum time, but tightly bound extracellular polymeric substances did not change significantly after short irradiation time. The results implied that LB-EPS played a more important role in the observed changes of filterability and dewaterability and that the double-layered extracellular polymeric substances extraction method showed marked implications to dewaterability.
  Water Environment Research 03/2013; 85(3):278-85.
• Article: Modeling methods for identifying critical source areas of bacteria: recent developments and future perspectives.

  Yangbin Tong, Zhiqiang Deng
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  ABSTRACT: Identification of critical source areas of bacteria in a watershed is essential to environmental management and restoration. As a result of the nonpoint and distributed nature of bacterial pollution in watersheds, it is often difficult to identify specific source areas of bacteria for remediation because bacteria collected from different sampling sites might display similar fingerprints. Over the past decade, extensive efforts have been made to identify microbial pollution sources, especially in watersheds. The primary objective of this study was to identify effective methods that can be applied to tracking critical source areas of bacteria in a watershed by a review of recent developments in several modeling methods. Comparisons of the models and their applications revealed that comprehensive watershed-scale source area tracking primarily involves two steps-geographical tracking and mathematical tracking. In terms of geographical tracking, bacterial source locations must be identified to prepare structural best management practices or low impact development for site treatments. For mathematical tracking, the quantity (strength) or release history of bacterial sources must be computed to develop total maximum daily loads (TMDLs) for bacterial load reduction and water quality restoration. Mathematically, source tracking is essentially an inverse modeling issue under uncertainty, requiring inverse modeling combined with a geostatistical method or an optimization algorithm. Consequently, combining biological methods, mathematical models, and sensor technologies (including remote sensing and in-situ sensing) provides an effective approach to identifying critical source locations of bacteria at the watershed-scale.
  Water Environment Research 03/2013; 85(3):259-69.
• Article: Multicausal analysis on water deterioration processes present in a drinking water treatment system.

  Li Wang, Fang Ma, Changlong Pang, Shaik Firdoz
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  ABSTRACT: The fluctuation of water turbidity has been studied during summer in the settling tanks of a drinking water treatment plant. Results from the multiple cause-effect model indicated that five main pathways interactively influenced thequalityof tank water. During rain, turbidity levels increased mainly as a result of decreasing pH and anaerobic reactions (partial effect = 68%). Increasing water temperature combined with dissolved oxygen concentration (partial effect = 64%) was the key parameterforcontrolling decreases in water turbidity during nighttime periods after a rainy day. The dominant factor influencing increases in turbidity during sunny daytime periods was algal blooms (partial effect = 86%). However, short-circuiting waves (partial effect = 77%) was the main cause for increased nighttime water turbidity after a sunny day. The trade offbetween regulatory pathways was responsible for environmental changes, and the outcome was determined by the comparative strengths of each pathway.
  Water Environment Research 03/2013; 85(3):232-8.
• Article: Hydrochemical characterization of a groundwater aquifer and its water quality in relation to irrigation in the Jinghuiqu irrigation district of China.

  Xiuhua Liu, Lin Li, Anyan Hu
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  ABSTRACT: The Jinghuiqu irrigation district is located in the semi-arid regions of northwestern China, where groundwater is the most important natural source for local industry, agriculture and residents. The present work was conducted in the Jinghuiqu irrigation district to characterize the groundwater aquifer, which has undergone long-term flood irrigation for over 2000 years. Isotopic and hydrochemical analyses, along with geological and hydrogeological tools, were used to determine the chemical properties and evolutionary processes of the groundwater aquifer. Results showed that the groundwater chemistry had changed significantly from 1990 to 2009. Water with concentrations of CaMgSO4 had decreased significantly, from 60% to 28% of the total water samples, during the period, while water with concentrations of NaSO4 and NaCl increased significantly, from 28% to 72%. The salinity of the groundwater increased rapidly and the affected area had expanded to most of the irrigation district. Stable isotope studies showed that most of the groundwater concentrations were derived from sulfate mineral dissolution. The minerals saturation indices (SI), ion ratios and oxygen isotope values of the groundwater indicated that the shallow groundwater had mainly experienced mineral dissolution, cation exchange, and mixing of the irrigated surface waters and groundwater. The groundwater quality had continuously evolved toward salinization as concentrations of SO4(2-) and Na+ grew to dominate it. Water quality risk analyses showed that most of the saline groundwater is not suitable for domestic and irrigation uses, especially in the middle and eastern parts of the irrigation district. These findings indicate that the irrigation district should strengthen the groundwater resources management.
  Water Environment Research 03/2013; 85(3):245-58.
• Article: Aerobic granulation in a sequencing batch reactor for the treatment of piggery wastewater.

  Dalei Zhang, Yanan Wang, Hongwei Li, Shaoran Wang, Yumei Jing
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  ABSTRACT: This study investigated the formation of aerobic granules fed with digested piggery wastewater. After 42 days of cultivation, small yellow granules with mean diameter of 0.4 mm were first observed in the reactor. Scanning electron microscope pictures showed the granules were compact, round structures with clear outer shapes and mainly composed of filamentous bacteria. Maximum chemical oxygen demand and ammonia removal ratios were 90.1 and 91.7%, respectively. The Monod equation, which was used to describe ammonium utilization, yielded a maximum rate of 6.25 mg (g volatile suspended solids)(-1) h(-1). The measurement of extracellular polymeric substances (EPS) content and three-dimensional excitation and emission matrix results showed that the EPS concentration increased during the granulation process. Fluorescence in situ hybridization analysis showed significant amounts of nitrifying bacteria in the aerobic granules. Results in this study provide insights to the treatment of piggery wastewater using aerobic granular sludge.
  Water Environment Research 03/2013; 85(3):239-44.
• Article: Hydrochemical modeling and assessment of groundwater contamination in northwest Sinai, Egypt.

  Mohamed El Alfy
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  ABSTRACT: This study aims to investigate groundwater geochemical characteristics, and to assess the effects of groundwater contamination in northwest Sinai, Egypt. A geographic information system, geochemical modeling, and statistical analyses tools were used. Twenty-five groundwater samples from a Quaternary aquifer were sampled. These water samples were analyzed for major, minor, and trace elements. The results of this study contribute to a better understanding of the hydrochemical characteristic as well as the anthropogenic processes of groundwater pollution. On the basis of these analyses, the geochemical parameters and the anomalous concentration of different elements enable the characterization of salinity sources of the brackish waters and the suspected sources of polluted water. Pollution sources are represented by waste disposal and agricultural activities as well as the probable upward leakage of highly saline water from the deeper aquifers and the saltwater intrusion. Pollution risk is high when the depth of the water table is shallow (0.3 to 15.0 m) and the aquifer has high hydraulic conductivity and poor matrix buffering capacity.
  Water Environment Research 03/2013; 85(3):211-23.
• Article: Influence of operating conditions on electrochemical reduction of nitrate in groundwater.

  Wenli Huang, Miao Li, Baogang Zhang, Chuanping Feng, Xiaohui Lei, Bin Xu
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  ABSTRACT: The influences of current density, initial pH, cation and anion concentrations, and the coexistence of Ca2+ and HCO3- on the efficiency of electrochemical nitrate reduction by a copper cathode and Ti/IrO2 anode in an undivided cell were studied. In the presence of 5 mM of sodium chloride (NaCl), the nitrate-nitrogen concentration decreased from 3.57 to 0.69 mM in 120 minutes, and no ammonia or nitrite byproducts were detected. The nitrate reduction rate increased as the current density increased. The electrochemical method performed well at an initial pH range of 3.0 to 11.0. The rate of nitrate reduction increased as concentrations of Na+, K+, and Ca2+ increased. The anion of the supporting electrolyte decreased the rate of reduction in the order Cl- > HCO3(2-) = CO3(2-) > SO4(2-) at both 5 mM and 10 mM of anion. The coexistence of Ca2+ and HCO3- ions could inhibit nitrate reduction. The concentration of nitrate-nitrogen in polluted groundwater decreased from 2.80 to 0.31 mM after electrolysis for 120 minutes.
  Water Environment Research 03/2013; 85(3):224-31.
• Article: Evaluating the effect of dissolved oxygen on simultaneous nitrification and denitrification in polyurethane foam contact oxidation reactors.

  Chong Tan, Fang Ma, Ang Li, Shan Qiu, Jianzheng Li
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  ABSTRACT: The effects of dissolved oxygen on simultaneous nitrification and denitrification were evaluated in polyurethane foam contact oxidation reactors in a municipal wastewater treatment process. It was observed that nitrate could be removed at low dissolved oxygen levels, but the removal rate was gradually reduced as the dissolved oxygen concentration increased to a higher level of 6.0 mg/L. Nitrogen removal remained optimal within the dissolved oxygen range of 0.5 to 1.0 mg/L. Denaturing gradient gel electrophoresis (DGGE) analysis revealed that the diversity of the microbial community changed accompanying dissolved oxygen values of 0.5 to 1.0 mg/L, 2.5 to 3.5 mg/L, 6.0 to 6.5 mg/L, and 10.0 to 12.0 mg/L, in turn, which was supported by the Shannon-Wiener index of 1.56, 1.71, 1.43, and 1.56, accordingly. Both DGGE profiling and phylogenetic analysis confirmed that the nitrifiers in reactors that are responsible for nitrification during the experiment include Nitrosospira sp., Nitrosomonas sp., and Nitrospira sp.
  Water Environment Research 03/2013; 85(3):195-202.
• Article: Evaluation of first flush phenomenon from bridge and parking lot sites in the Gyeongan watershed in Korea.

  Sheeraz Memon, Sunghoon Go, Chang-Hee Lee
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  ABSTRACT: Urban land-use areas with high imperviousness, such as bridges, highways, and parking lots, are known to be responsible for relatively large amounts of stormwater runoff and high concentration of pollutants particularly in the "first flush". This study was conducted to determine the effect of first flush from urban land-use sites located in Yongin City, Korea, on runoff amounts and pollutant concentration. It was observed that, on most pollutant parameters, the effect was apparent when the data were analyzed qualitatively but it was relatively weak when analyzed quantitatively. A stronger effect was observed from a bridge site than from a parking lot site. Pollutant loads, washed off at 40 and 60% runoff volume, respectively, were also determined for further analysis of the first flush effect to find an improved strategy for best management practices. In this study, no correlation was observed between rainfall intensity and runoff duration with first flush effect.
  Water Environment Research 03/2013; 85(3):203-10.
• Article: Comprehensive review and compilation of treatment for azo dyes using microbial fuel cells.

  V Murali, Soon-An Ong, Li-Ngee Ho, Yee-Shian Wong, Nasrul Hamidin
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  ABSTRACT: Microbial fuel cells (MFCs) represent an emerging technology that focuses on power generation and effluent treatment. This review compiles articles related to MFCs using azo dye as the substrate. The significance of the general components in MFCs and systems of MFCs treating azo dye is depicted in this review. In addition, degradation of azo dyes such as Congo red, methyl orange, active brilliant red X-3B, amaranth, reactive blue 221, and acid orange 7 in MFCs are summarized. Further exploration and operational modification are suggested to address the challenges of complete removal of azo dye with maximum power generation in an MFC. In addition, a sequential treatment system with MFCs is suggested for complete mineralization of azo dye.
  Water Environment Research 03/2013; 85(3):270-7.
• Article: Nitrate and salt water contamination associated with the transition of an agrarian basin into an irrigated area.

  Raphael Abrahao, Jesús Causapé, David Moreno-Mateos, Francisco Comín
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  ABSTRACT: The introduction of irrigation to agrarian areas involves several environmental changes that can be aggravated by physical and agronomic factors. The aim of this study is to analyze the spatiotemporal dynamics of the environmental impact on water resources that result from the transition of an agrarian basin into an irrigated area. During five hydrological years, a spatiotemporal comparison was carried out on the quantity and quality of drainage from the four zones in which the study area was subdivided. Introduction of irrigation activities incorporated flows that lowered salinity and increased nitrate concentration in the basin. The zones/years with most irrigation showed the greatest exports of salts and nitrates, with temporal variations related to rainfall patterns and spatial variations related to soil salinity and nitrogenous fertilization. The agro-environmental impacts of the gradual introduction of irrigation into a previously non-irrigated area were congruent to that of established irrigation areas with similar characteristics.
  Water Environment Research 02/2013; 85(2):105-12.
• Article: Development of failure scenarios for biosolids land application risk assessment.

  Heather C Galada, Patrick L Gurian, Mira S Olson, Jingjie Teng, Arun Kumar, Michael Wardell, Sara Eggers, Elizabeth Casman
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  ABSTRACT: Although deviations from standard guidance for land application of biosolids occur in practice, their importance is largely unknown. A list of such deviations (plausible failure scenarios) were identified at a workshop of industry, regulators, and academic professionals. Next, a survey of similar professionals was conducted to rank the plausible failure scenarios according to their severity, frequency, incentive to ignore control measures, gaps in existing control processes, public concern, and overall concern. Survey participants rated intentional dumping (unpermitted disposal) as the most severe of the failure scenarios, lack of worker protection as the most frequent scenario, and application of Class A biosolids that have failed to meet treatment standards as the scenario for which incentives to ignore control measures are highest. Failure of public access restrictions to application sites was the scenario for which existing controls were judged the weakest; application of biosolids too close to wells was ranked highest for public concern and for overall concern. Two scenarios for which existing controls were considered weaker, site restriction violations and animal contact leading to human exposure, were also rated as frequently occurring. Both scenarios are related in that they (1) involve inappropriate access to a site before the required time has elapsed, and (2) could be addressed through similar biosolids management measures.
  Water Environment Research 02/2013; 85(2):141-50.
• Article: Enhanced methane generation during theromophilic co-digestion of confectionary waste and grease-trap fats and oils with municipal wastewater sludge.

  Heidi L Gough, Diane Nelsen, Christopher Muller, John Ferguson
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  ABSTRACT: Recent interest in carbon-neutral biofuels has revived interest in co-digestion for methane generation. At wastewater treatment facilities, organic wastes may be co-digested with sludge using established anaerobic digesters. However, changes to organic loadings may induce digester instability, particularly for thermophilic digesters. To examine this problem, thermophilic (55 degrees C) co-digestion was studied for two food-industry wastes in semi-continuous laboratory digesters; in addition, the wastes' biochemical methane potentials were tested. Wastes with high chemical oxygen demand (COD) content were selected as feedstocks allowing increased input of potential energy to reactors without substantially altering volumetric loadings. Methane generation increased while reactor pH and volatile solids remained stable. Lag periods observed prior to methane stimulation suggested that acclimation of the microbial community may be critical to performance during co-digestion. Chemical oxygen demand mass balances in the experimental and control reactors indicated that all of the food industry waste COD was converted to methane.
  Water Environment Research 02/2013; 85(2):175-83.
• Article: Effects of recharge and discharge on delta2H and delta18O composition and chloride concentration of high arsenic/fluoride groundwater from the Datong Basin, northern China.

  Xianjun Xie, Yanxin Wang, Chunli Su, Mengyu Duan
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  ABSTRACT: To better understand the effects of recharge and discharge on the hydrogeochemistry of high levels of arsenic (As) and fluoride (F) in groundwater, environmental isotopic composition (delta2H and delta18O) and chloride (Cl) concentrations were analyzed in 29 groundwater samples collected from the Datong Basin. High arsenic groundwater samples (As > 50 micog/L) were found to be enriched in lighter isotopic composition that ranged from -92 to -78 per thousand for deuterium (delta2H) and from -12.5 to -9.9 per thousand for oxygen-18 (delta18O). High F-containing groundwater (F > 1 mg/L) was relatively enriched in heavier isotopic composition and varied from -90 to -57 per thousand and from -12.2 to -6.7 per thousand for delta2H and delta18O, respectively. High chloride concentrations and delta18O values were primarily measured in groundwater samples from the northern and southwestern portions of the study area, indicating the effect of evaporation on groundwater. The observation of relatively homogenized and low delta18O values and chloride concentrations in groundwater samples from central part of the Datong Basin might be a result of fast recharge by irrigation returns, which suggests that irrigation using arsenic-contaminated groundwater affected the occurrence of high arsenic-containing groundwater in the basin.
  Water Environment Research 02/2013; 85(2):113-23.
• Article: Prioritizing subwatersheds for stormwater pollution to Wachusett Reservoir.

  Kyung Hwa Cho, Mi-Hyun Park
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  ABSTRACT: The Wachusett Reservoir is a primary drinking water resource for the greater Boston, Massachusetts, area. With a drainage area of 280 km2, the watershed has been gradually urbanized with increased residential, commercial, industrial, and transportation land uses. Increased impervious surface area as a result of urbanization results in increased runoff volume and pollutant loads to the reservoir. This study estimated annual stormwater pollutant mass loads in the watershed to prioritize sub-basins and to identify areas susceptible to stormwater pollution. Catchment Prioritization Index (CPI) was calculated using annual stormwater pollutant mass loads, which were further used to identify clustered hotspots through application of the Getis-Ord Gi* statistic. Validation with observed data showed higher levels of fecal coliform bacteria loading from identified hotspots. This approach will be useful to prioritize sub-basins for future (1) development of stormwater monitoring strategies and (2) best management practices (BMPs) in the watershed.
  Water Environment Research 02/2013; 85(2):158-66.
• Article: Characterization of sulfur in raw and anaerobically digested municipal wastewater treatment sludges.

  Weiwei Du, Wayne Parker
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  ABSTRACT: A microwave-enhanced acid digestion method that was integrated with inductively coupled plasma-atomic emission spectrometry was developed and validated for determining total, soluble, and precipitated sulfur in wastewater treatment sludges. The coefficient of variation of this method was less than 4.0%. The recovery of dosed sulfur from sludge samples was between 97.1% and 100.5%. The composition of sulfur in primary and waste-activated sludge (WAS) before and after anaerobic digestion at 35 and 55 degrees C was characterized by employing this developed method. There was not an apparent relationship between the precipitated sulfur and nonsoluble iron concentrations in sludges. Raw WAS had a more consistent organic sulfur fractionation because of its relatively homogeneous composition. The organic-sulfur-containing components (proteins) of WAS had reduced degradability as compared with that in primary sludge during anaerobic digestion. Digestion at 55 degrees C increased solubilization but not ultimate conversion of organic sulfur in sludge.
  Water Environment Research 02/2013; 85(2):124-32.
• Article: Adsorption of lead(II) by silica/cell composites from aqueous solution: kinetic, equilibrium, and thermodynamics studies.

  Hong-Xiang Ou, Yu-Jun Song, Qian Wang, Jian-Ming Pan, Wei-Bai Bian, Cheng-Wu Yi, Yong-Sheng Yan
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  ABSTRACT: Silica/cell composites were prepared for the adsorption of lead ions, Pb(II), from aqueous solution in a batch system. The silica/cell composites possessed micropores, high surface area, and abundant functional groups. Adsorption performance was investigated by analyzing the effects of such factors as the initial pH, contact time with different initial concentration, and initial Pb(II) concentration at different temperature. The kinetic data were fitted to pseudo-second-order and intraparticle diffusion kinetic models. The results were better fitted by the pseudo-second-order kinetic model. Intraparticle diffusion increased with an increase of initial concentration and the sorption process was controlled by film diffusion. The Langmuir isotherm model was fitted to the experimental data significantly better than Freundlich and Dubinin-Radushkevich isotherm models. The maximum adsorption capacity was 97.10 mg g(-1), according to the Langmuir isotherm model. Thermodynamics parameters confirmed the spontaneous, endothermic, and entropy-gained nature within the studied temperature range (from 298 to 318 K). The composites could be effectively desorbed by the 2.0 mol L(-1) HNO3 solution and would be a potential adsorbent.
  Water Environment Research 02/2013; 85(2):184-91.
• Article: Enhanced adsorption of fluoride from aqueous solution using an iron-modified attapulgite adsorbent.

  Z L He, G K Zhang, W Xu
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  ABSTRACT: Attapulgite modified with iron was used as an adsorbent for fluoride removal from aqueous solutions. The pristine attapulgite and the iron-modified attapulgite composite were characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) techniques, and the pH point of zero charge measurement. The XRD analysis indicates the existence of iron oxide hydroxide (FeO[OH]) in the iron-modified attapulgite composite. The FT-IR spectra of the iron-modified attapulgite composite before and after adsorption indicate that the involvement of the hydroxide radical in the fluoride adsorption. The effects of pH, contact time, initial concentration, and temperature on fluoride adsorption by the adsorbent were studied in a batch system. Kinetics studies show that the fluoride adsorption kinetics over the adsorbent is well-described by the pseudo-second-order kinetic model. The fluoride adsorption isotherm is well-fitted by the Langmuir model. Desorption studies show that the iron-modified attapulgite adsorbent can be easily regenerated at pH 12.5. The adsorption mechanism is discussed in detail.
  Water Environment Research 02/2013; 85(2):167-74.
• Article: Effect of wastewater quality parameters on oxidation by tin oxide anodes.

  Amy L Teel, Dennis D Finn, Richard J Watts
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  ABSTRACT: The use of tin oxide anodes (TOAs) has been proposed for the disinfection of wastewater effluents and concurrent treatment of emerging contaminants. The common water quality constituents suspended solids, chemical oxygen demand (COD), alkalinity, ammonia-nitrogen, nitrite-nitrogen, and nitrate-nitrogen were investigated for their effect on oxidation performance by TOAs. Relative oxidant generation rates were not affected by increasing concentrations of suspended solids, COD, alkalinity, ammonia-nitrogen, or nitrate-nitrogen. Although nitrite-nitrogen did compete for oxidants generated by TOAs, nitrite is not usually present in oxygenated effluents. Chemical oxygen demand, ammonia, and nitrite were oxidized in the TOA systems, primarily through a non-hydroxyl radical mechanism. This research demonstrates that a majority of the common water quality constituents did not negatively affect TOA oxidation performance. Tin oxide anodes represent a potentially low cost and low maintenance option for single-step disinfection and treatment of emerging contaminants in wastewater effluents.
  Water Environment Research 02/2013; 85(2):151-7.
• Article: Remediation of nonaqueous phase liquid polluted sites using surfactant-enhanced air sparging and soil vapor extraction.

  Chuan-Yu Qin, Yong-Sheng Zhao, Yan Su, Wei Zheng
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  ABSTRACT: A two-dimensional laboratory sand tank was installed to study the remediation efficiency of surfactant-enhanced air sparging (-SEAS) coupled with soil vapor extraction (SVE) in nonaqueous phase liquid (NAPL) polluted sites. During initial stages of remediation, it was more reasonable to use conventional air sparging coupled with SVE. When most free NAPLs were removed and contaminant removal rate was maintained at a relatively low level, surfactant was added to the groundwater. During enhanced remediation, lower interfacial tension caused residual NAPLs in the porous media to slightly migrate, making the downstream contaminant concentration somewhat higher. The polluted area, however, was not more enlarged than before. The decrease in surface tension resulted in increased air saturation in the groundwater and the extent of the air influence zone. After 310 hours, 78.7% of the initial chlorobenzene mass had volatilized, 3.3% had migrated out of the sand profile, 17.5% was in the vadose zone, and 0.5% remained in the groundwater, thus revealing that SEAS/SVE can effectively improve the remediation of NAPL polluted sites.
  Water Environment Research 02/2013; 85(2):133-40.