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  • A membrane bioreactor with iron dosing and acidogenic co-fermentation for enhanced phosphorus removal and recovery in wastewater treatment
    Water Res. (IF 6.942) Pub Date : 2017-11-17
    Ruo-hong Li, Xiao-mao Wang, Xiao-yan Li

    A novel phosphorous (P) removal and recovery process using a membrane bioreactor (MBR) with ferric iron dosing and acidogenic co-fermentation was developed for municipal wastewater treatment. The very different solubility of Fe(III)-P and Fe(II)-P complex and the microbial transformation of Fe(III) to Fe(II) were utilized for P removal and recovery. By means of Fe-induced precipitation, chemical P removal was effectively achieved by an MBR with a flat-plate ceramic membrane; however, the Fe(III)-P solids accumulated in the MBR that constituted a significant fraction of the activated sludge. Anaerobic co-fermentation of the MBR sludge and food waste in a side-stream allowed the extraction of P and Fe from the sludge into the supernatant. The P in the supernatant was recovered as a fertilizer resource, while the sludge was returned to the MBR tank. The experimental results show that by adding FeCl3 at 20 mg Fe/L into the influent of domestic wastewater, about 95.6% of total P could be removed by the MBR. One fifth (20%) of the sludge in the MBR was circulated daily through the side-stream fermenters for co-fermentation with cooked rice as the model food waste. The sludge underwent acidogenesis and dissimilatory iron reduction, resulting in a drop of the pH to below 5.0 and reduction of Fe(III) to Fe(II). Owing to the high solubility of the Fe(II)-P complex, P and Fe were then dissolved and released from the sludge into the supernatant. By simply adjusting the solution pH to 8.0, the P and Fe(II) in the supernatant readily re-precipitated to form vivianite for the P recovery. Using the iron dosing MBR and side-stream sludge fermentation, an overall P recovery efficiency of 62.1% from wastewater influent can be achieved, and the problem of inorganic build-up in the MBR is effectively alleviated.

    更新日期:2017-11-17
  • Droplet distribution and airborne bacteria in an experimental shower unit
    Water Res. (IF 6.942) Pub Date : 2017-11-16
    C.E. Estrada-Perez, K.A. Kinney, J.P. Maestre, Y.A. Hassan, M.D. King

    Although human exposure to water aerosols is common in residential showers, the droplet distribution patterns generated in showers are not well understood nor is the bacteria released during shower operation. In this study, a two-phase flow Particle Tracking Velocimetry (PTV) algorithm was successfully used to characterize the spatial spray pattern and velocity field in two experimental showers (one low-flow and one high-flow). In addition, the airborne bacteria present in the shower over nearly 5 months of controlled operation was determined for both showers. The results indicate that the droplet velocity out of the low-flow showerhead (which had fewer orifices) was significantly higher than that out of the high-flow showerhead resulting in a higher aerosol number concentration in the low-flow shower and more consistent wetting of the shower wall. Both showerheads generated droplets in the respirable range and genera of potential health concern were observed in the shower aerosols measured both prior to and following shower operation. The study provides one of the first visualizations of droplet spray patterns in residential showers and provides insight into the airborne bacteria present in showers.

    更新日期:2017-11-17
  • Spatial and temporal variability of bacterial indicators and pathogens in six California reservoirs during extreme drought
    Water Res. (IF 6.942) Pub Date : 2017-11-16
    Melissa L. Partyka, Ronald F. Bond, Jennifer A. Chase, Edward R. Atwill

    California has one of the largest systems of surface water reservoirs in the world, providing irrigation water to California's agriculturally productive Central Valley. Irrigation water is recognized as a vehicle for the microbial contamination of raw produce and must be monitored according to new federal regulation. The purpose of this study was to further understanding of the variability of fecal indicator bacteria (Escherichia coli and fecal coliforms) and pathogens (E. coli O157:H7, Non-O157 shiga toxin-producing E. coli and Salmonella) along both horizontal and vertical profiles within California reservoirs. Monthly sampling was conducted in six reservoirs located in the foothills of the Western Sierra Nevada during the summer irrigation season and extreme drought conditions of 2014 (n = 257). Concentrations of fecal indicator bacteria were highly variable between reservoirs (p < 0.05) and along the horizontal profile (p < 0.001) from upstream to downstream, with higher concentrations typically found outside of the reservoirs than within. Though many of the reservoirs were thermally stratified, bacterial concentrations were not associated with water temperature (p > 0.05) or any one particular depth strata (p < 0.05). However, prevalence of Salmonella and non-O157 STEC (16/70 and 9/70 respectively) was higher in the deep strata than in mid or surface layers. Water quality outcomes were We found no statistical association between samples collected downstream of reservoirs and those from the reservoirs themselves. Continued monitoring and modeling of both bacterial indicators and enteric pathogens are critical to our ability to estimate the risk of surface irrigation water supplies and make appropriate management decisions.

    更新日期:2017-11-16
  • CTAB and SDS assisted facile fabrication of SnO2 nanoparticles for effective degradation of carbamazepine from aqueous phase: A systematic and comparative study of their degradation performance
    Water Res. (IF 6.942) Pub Date : 2017-11-15
    Shamima Begum, M. Ahmaruzzaman

    In the present study, SnO2 nanoparticles were successfully synthesized by chemical precipitation method using anhydrous aspartic acid and surfactant at two annealing temperatures, 300 °C and 600 °C. The effect of surfactants cationic CTAB and anionic SDS on the synthesized SnO2 nanoparticles (NPs) were studied elaborately. In this article, for the first time, SnO2 NPs were employed as an excellent photocatalyst in the degradation of carbamazepine (CBZ), a popular antiepileptic drug which is most commonly detected pharmaceutically active compounds (PhACs) in municipal wastewater under UV-C light irradiation. Comparative studies between the photocatalytic activity of SnO2 NPs synthesized with CTAB (SC1) and SDS (SS1) on the degradation of the CBZ drug were investigated. Parameters like the effect of catalytic loading, initial concentration, pH and contact time were also studied for optimization. The results indicate that SC1 is a better photocatalyst with rate constant 6.66 × 10−2 min−1 than SS1with rate 5.7 × 10−2 min−1. To determine the transformation product formed on the photodegradation LCMS (ESI) analysis was done. The synthesized SnO2 NPs can be recycled up to 8th cycles without any notable alteration in its photocatalytic activity.

    更新日期:2017-11-15
  • Mechanism and efficiency of contaminant reduction by hydrated electron in the sulfite/iodide/UV process
    Water Res. (IF 6.942) Pub Date : 2017-11-15
    Keer Yu, Xuchun Li, Liwei Chen, Jingyun Fang, Huali Chen, Qiangbiao Li, Nianping Chi, Jun Ma

    Advanced reduction by the extremely strong reducing species, hydrated electron (eaq−), is a promising and viable approach to eliminate a wide variety of persistent and toxic contaminants. In this study, we proposed a sulfite/iodide/UV process, which offered efficient production of eaq− for contaminant reduction. Using monochloroacetic acid (MCAA) as a simple eaq− probe, the availability of eaq− was assessed, and the mechanism involving the roles of S(IV) and iodide in the process was elucidated. A pronounced synergistic effect of S(IV) and iodide was observed in MCAA reductive dechlorination. The efficiency was much more dependent on the iodide concentration due to its higher absorptivity and quantum yield of eaq−. S(IV) played a dual role by producing eaq− via photoionization of SO32− and by reducing the reactive iodine species formed to avoid their scavenging of eaq−. When S(IV) was available, cycling of iodide occurred, favoring the constant eaq− production. The formation and transformation kinetics of sulfite radical were studied to verify the roles of S(IV) and iodide in the process. A kinetic model of MCAA dechlorination was also developed to quantify the eaq−-initiated reduction efficiency, highlighting the effects of S(IV), iodide, and pH. High pH favored the reduction, and the process was still effective in field surface water. This study underscores the importance of producing eaq− efficiently and of minimizing the eaq− scavenging of intermediates inherently formed and accumulated, and highlights the potential of the sulfite/iodide/UV process to efficiently eliminate recalcitrant contaminants.

    更新日期:2017-11-15
  • Inventory, loading and discharge of synthetic phenolic antioxidants (SPAs) and their metabolites in wastewater treatment plants
    Water Res. (IF 6.942) Pub Date : 2017-11-15
    Wei Wang, Kurunthachalam Kannan

    Little is known about the occurrence and fate of synthetic phenolic antioxidants (SPAs) and their metabolites in wastewater treatment plants (WWTPs). In this study, inventory, source, mass loading, and discharge of five SPAs, including 2,6-di-tert-butyl-4-hydroxytoluene (BHT) and four of its metabolites were examined, based on the concentrations determined in wastewater influent, primary effluent, final effluent, suspended particulate matter (SPM), and sludge collected from two WWTPs (denoted as WWTPA and WWTPB) in the Albany area of New York State. The respective median concentrations of sum of SPAs (ΣSPAs = 6 compounds including metabolites) and SPA-metabolites (Σmetabolites = 4 metabolites) were 2455–3330 and 290–465 ng/L in influents, and 1580–1604 and 511–822 ng/L in final effluents. Adsorption to sludge (ΣSPAs ranged as 2420–4680 ng/g dry wt) accounted for ∼1% of the SPA removal. The removal efficiency (RE) for BHT in WWTPs ranged between 62.3% and 76.2%, whereas negative REs were found for SPA-metabolites ([-3020%]-[−65.6%]). WWTP-based mass loading of BHT accounted for ∼4%–10% of the total production volume reported in the USA, whereas ∼1.0% of the annual production of BHT was discharged from WWTP through effluents. BHT present in personal care products was estimated to explain for >91% of the mass loading source into WWTPs.

    更新日期:2017-11-15
  • Intrinsic tradeoff between kinetic and energetic efficiencies in membrane capacitive deionization
    Water Res. (IF 6.942) Pub Date : 2017-11-15
    Li Wang, Shihong Lin

    Significant process has been made over recent years in capacitive deionization (CDI) to develop novel system configurations, predictive theoretical models, and high-performance electrode materials. To bring CDI to large scale practical applications, it is important to quantitatively understand the intrinsic tradeoff between kinetic and energetic efficiencies, or the relationship between energy consumption and the mass transfer rate. In this study, we employed both experimental and modeling approaches to systematically investigate the tradeoff between kinetic and energetic efficiencies in membrane CDI (MCDI). Specifically, we assessed the relationship between the average salt adsorption rate and specific energy consumptions from MCDI experiments with different applied current densities but a constant effluent salinity. We investigated the impacts of feed salinity, diluted water salinity, diluted water volume per charging cycle, and electrode materials on the kinetics-energetics tradeoff. This tradeoff can be employed to optimize the design and operation of CDI systems and compare the performance of different electrode materials and CDI systems.

    更新日期:2017-11-15
  • Deiodination of iopamidol by zero valent iron (ZVI) enhances formation of iodinated disinfection by-products during chloramination
    Water Res. (IF 6.942) Pub Date : 2017-11-14
    Huiyu Dong, Zhimin Qiang, Junfeng Lian, Jin Li, Jianwei Yu, Jiuhui Qu

    Iodinated X-ray contrast media (ICM) is considered as one of iodine sources for formation of toxic iodinated disinfection byproducts (I-DBPs) during disinfection. This study investigated transformation of a typical ICM, iopamidol (IPM) by zero valent iron (ZVI) and the effect of transformation on the formation of I-DBPs during chloramination. It was found that the presence of ZVI could deiodinate IPM into I− and the transformation of IPM exhibited a pseudo-first-order kinetics. Acidic circumstance, SO42−, Cl− and monochloramine could promote the transformation of IPM by ZVI, while SiO32− inhibited the transformation of IPM. Moreover, the transformation of IPM by ZVI changed both the formed species and amounts of I-DBPs during chloramination. During the chloramination of IPM-containing water, CHCl2I and iodoacetic acid were the predominant iodinated trihalomethanes (I-THMs) and iodinated haloacetic acids (I-HAAs), respectively in the absence of ZVI, while CHI3 and triiodoacetic acid became the predominant ones with 1.0 g L−1 ZVI. The addition of 5.0 g L−1 ZVI increased I-DBPs formation amounts by 6.0 folds after 72 h and maximum formation of I-DBPs occurred at pH 5.0. Enhanced I-DBPs formation was also observed with various real water sources. Given that ZVI ubiquitously exists in the unlined cast iron distribution pipes, the deiodination of IPM by ZVI during distribution may increase the formation of I-DBPs, which needs receive enough attention.

    更新日期:2017-11-15
  • Identification of mutagenic transformation products generated during oxidation of 3-methyl-4-nitrophenol solutions by orbitrap tandem mass spectrometry and quantitative structure–activity relationship analyses
    Water Res. (IF 6.942) Pub Date : 2017-11-14
    Taku Matsushita, Shiho Honda, Taisuke Kuriyama, Yuki Fujita, Takashi Kondo, Yoshihiko Matsui, Nobutaka Shirasaki, Hirokazu Takanashi, Takashi Kameya

    We used Ames assays to investigate the effects of ozonation (designated O3), ozonation followed by chlorination (O3/Cl), an advanced oxidation process (AOP, UV/H2O2), and AOP followed by chlorination (AOP/Cl) on the mutagenicity of solutions of 3-methyl-4-nitrophenol (3M4NP), a major environmental degradation product of the organophosphorus insecticide fenitrothion. Whereas O3 did not induce mutagenicity, O3/Cl, AOP, and AOP/Cl converted 3M4NP into mutagenic transformation products (TPs). Using liquid chromatography–mass spectrometry, we detected a total of 138 peaks in the solutions subjected to O3/Cl, AOP, and AOP/Cl. To elucidate the TPs responsible for the observed mutagenicity, we performed simple regression analyses of the relationship between the area of each peak and the observed mutagenicity of samples withdrawn periodically during each oxidation process. The area of each of 10 peaks was found to be positively correlated (r2 ≥ 0.8) with the observed mutagenicity, suggesting that the TPs corresponding to these peaks contributed to the mutagenicity. After taking into account the consistency of mutagenicity induction by the oxidation processes and analyzing the peaks by tandem mass spectrometry, we identified 3 TPs, corresponding to 6 peaks, as candidate mutagens. These TPs were assessed by means of 4 quantitative structure–activity relationship (QSAR) models, and all 3 were predicted to be mutagenic by at least one model. This result was consistent with our assumption that these TPs were mutagens. Ames assays of an authentic sample of one of the 3 TPs revealed that it did not contribute to the mutagenicity. This left 3-methoxy-4-nitrophenol and 2-[(E)-[(2,5-dihydroxyphenyl) methylidene]amino]-5-dihydroxybenzaldehyde on the list of mutagens suspected of contributing to the mutagenicity induced by AOP. No TPs were identified as candidate mutagens responsible for the mutagenicity induced by O3/Cl and AOP/Cl.

    更新日期:2017-11-14
  • Mechanistic insights into alginate fouling caused by calcium ions based on terahertz time-domain spectra analyses and DFT calculations
    Water Res. (IF 6.942) Pub Date : 2017-11-14
    Meijia Zhang, Huachang Hong, Hongjun Lin, Liguo Shen, Haiying Yu, Guangcai Ma, Jianrong Chen, Bao-Qiang Liao

    Fouling mechanisms underlying the filtration behaviors of alginate solution caused by calcium addition were investigated by Terahertz time-domain spectroscopy (THz-TDS) and density functional theory (DFT) techniques. Filtration tests showed that specific filtration resistance (SFR) of alginate solution (0.75 g·L-1) monotonously increased with calcium addition at a relatively low range of calcium concentration (0-1.0 mM), and SFR (2.61 × 1015 m·kg-1) of alginate solution with 1.0 mM calcium addition was extremely high as compared with sludge suspension. Characterizations by X-ray photoelectric spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric analysis (TGA) showed that the composition of functional groups, elements and thermal stability of alginate was not apparently affected by calcium concentration. Howbeit, THz-TDS spectra showed that calcium addition caused structural variation of alginate polymer in solution. DTF calculation results showed that initial binding of alginate chains induced by calcium ions preferentially occurred in intermolecular other than intramolecular, and moreover, the two alginate chains bridged by a calcium atom tend to stretch in a tetrahedron structure (cross to each other) other than parallel to each other. According to these results, “chemical potential gap” depicted by Flory-Huggins theory was suggested to be responsible for the filtration behaviors of alginate solution caused by calcium addition. This study improved the mechanistic insights into membrane fouling.

    更新日期:2017-11-14
  • D-Tyrosine loaded nanocomposite membranes for environmental friendly, long-term biofouling control
    Water Res. (IF 6.942) Pub Date : 2017-11-14
    Cong Yu, Jinjian Wu, Gilherme Zin, Marco Di Luccio, Donghui Wen, Qilin Li

    Strategies to control biofouling without using antimicrobial chemicals are needed to prevent spreading of antibiotic resistance genes and disruption of microbial activities in biological treatment. This study developed an environmentally friendly biofouling resistant membrane by incorporating D-tyrosine onto a commercial nanofiltration membrane using FAU type zeolite nanoparticles covalently bound to the membrane surface as carriers for slow release. The D-tyrosine loaded membrane had similar water permeability as the unmodified membrane, but greatly reduced initial cell attachment and strongly inhibited subsequent biofilm formation without inactivating the bacteria. The membrane slowly released D-tyrosine in the time course of over 5 days, and retained its anti-biofouling capability in repeated 24 h efficacy tests for as long as 6 days. In nanofiltration operation, the D-tyrosine incorporated zeolite coating completely inhibited cell adhesion on the membrane surface and significantly alleviated membrane flux decline.

    更新日期:2017-11-14
  • Optimal allocation of physical water resources integrated with virtual water trade in water scarce regions: A case study for Beijing, China
    Water Res. (IF 6.942) Pub Date : 2017-11-14
    Quanliang Ye, Yi Li, La Zhuo, Wenlong Zhang, Wei Xiong, Chao Wang, Peifang Wang

    This study provides an innovative application of virtual water trade in the traditional allocation of physical water resources in water scarce regions. A multi-objective optimization model was developed to optimize the allocation of physical water and virtual water resources to different water users in Beijing, China, considering the trade-offs between economic benefit and environmental impacts of water consumption. Surface water, groundwater, transferred water and reclaimed water constituted the physical resource of water supply side, while virtual water flow associated with the trade of five major crops (barley, corn, rice, soy and wheat) and three livestock products (beef, pork and poultry) in agricultural sector (calculated by the trade quantities of products and their virtual water contents). Urban (daily activities and public facilities), industry, environment and agriculture (products growing) were considered in water demand side. As for the traditional allocation of physical water resources, the results showed that agriculture and urban were the two predominant water users (accounting 54% and 28%, respectively), while groundwater and surface water satisfied around 70% water demands of different users (accounting 36% and 34%, respectively). When considered the virtual water trade of eight agricultural products in water allocation procedure, the proportion of agricultural consumption decreased to 45% in total water demand, while the groundwater consumption decreased to 24% in total water supply. Virtual water trade overturned the traditional components of water supplied from different sources for agricultural consumption, and became the largest water source in Beijing. Additionally, it was also found that environmental demand took a similar percentage of water consumption in each water source. Reclaimed water was the main water source for industrial and environmental users. The results suggest that physical water resources would mainly satisfy the consumption of urban and environment, and the unbalance between water supply and demand could be filled by virtual water import in water scarce regions.

    更新日期:2017-11-14
  • Biofilms as a sink for antibiotic resistance genes (ARGs) in the Yangtze Estuary
    Water Res. (IF 6.942) Pub Date : 2017-11-13
    Xing-pan Guo, Yi Yang, Da-pei Lu, Zuo-shun Niu, Jing-nan Feng, Yu-ru Chen, Fei-yun Tou, Emily Garner, Jiang Xu, Min Liu, Michael F. Hochella Jr.

    Biofilms are ubiquitous throughout aquatic environments and they are thought to promote the acquisition and dissemination of antibiotic resistant genes (ARGs). This study focused on the occurrence and distribution of five types of ARG in naturally-occurring biofilms, in comparison to associated sediment and water samples, from the Yangtze Estuary, which borders the meta-city of Shanghai, China. The detection frequency and abundances of most ARGs showed the following order: biofilm > sediment > water, which can be attributed to a high level of antibiotics and metals that can accelerate the generation and propagation of ARGs in biofilms. Most of ARG abundances were contributed by extracellular DNA (eDNA) in biofilm and sediment samples. ARGs (sul1, sul2, tetA and tetW) in eDNA were significantly correlated with TOC in both biofilm and sediment samples. Furthermore, both intracellular DNA-associated ARGs per gram of microbial biomass carbon (MBC) and eDNA-associated ARGs per gram of non-MBC and were higher in biofilms than sediments, and the partitioning coefficients of ARGs in eDNA between biofilm and water were higher than those between sediment and water. Our results provide new insight for evaluating the occurrence and abundance of ARGs in aquatic environments, confirming that biofilms are a significant sink for ARGs in the estuarine environment.

    更新日期:2017-11-14
  • Quantifying the flow efficiency in constant-current capacitive deionization
    Water Res. (IF 6.942) Pub Date : 2017-11-11
    Steven A. Hawks, Jennifer M. Knipe, Patrick G. Campbell, Colin K. Loeb, McKenzie A. Hubert, Juan G. Santiago, Michael Stadermann

    Here we detail a previously unappreciated loss mechanism inherent to capacitive deionization (CDI) cycling operation that has a substantial role determining performance. This mechanism reflects the fact that desalinated water inside a cell is partially lost to re-salination if desorption is carried out immediately after adsorption. We describe such effects by a parameter called the flow efficiency, and show that this efficiency is distinct from, and yet multiplicative with, other highly-studied adsorption efficiencies. Flow losses can be minimized by flowing more feed solution through the cell during desalination; however, this also results in less effluent concentration reduction. While the rationale outlined here is applicable to all CDI cell architectures that rely on cycling, we validate our model with a flow-through electrode CDI device operated in constant-current mode. We find excellent agreement between flow efficiency model predictions and experimental results, thus giving researchers simple equations by which they can estimate this distinct loss process for their operation.

    更新日期:2017-11-11
  • The application of bacteriophages as novel indicators of viral pathogens in wastewater treatment systems
    Water Res. (IF 6.942) Pub Date : 2017-11-09
    Edgard Dias, James Ebdon, Huw Taylor

    Many wastewater treatment technologies have been shown to remove bacterial pathogens more effectively than viral pathogens and, in aquatic environments, levels of traditional faecal indicator bacteria (FIB) do not appear to correlate consistently with levels of human viral pathogens. There is, therefore, a need for novel viral indicators of faecal pollution and surrogates of viral pathogens, especially given the increasing importance of indirect and direct wastewater reuse. Potential candidates include bacteriophages (phages) and the study described here sought to elucidate the relationship between three groups of phages (somatic coliphages (SOMPH), F RNA coliphages (F RNAPH) and human-specific phages infecting B. fragilis (Bf124 PH) – enumeration using double layer agar technique) and viral pathogens (human adenovirus (HuAdV) and norovirus (NoV) – enumeration using molecular methods) through full-scale municipal wastewater treatment processes. FIB (faecal coliforms (FC) and intestinal enterococci (ENT) – enumeration using membrane filtration) were also monitored. Samples were collected every fortnight, during a twelve-month period, at each stage of four full-scale wastewater treatment plants (WWTP) in southern England (two activated sludge (AS) and two trickling filter (TF) plants) (n = 360 samples). FIB and SOMPH were consistently found in all samples tested, whereas F RNAPH, Bf124 PH and HuAdV were less frequently detected, especially following AS treatment. The detection rate of NoV was low and consequently discussion of this group of viruses is limited. Concentrations of SOMPH and FIB were statistically higher (p value < 0.05) than concentrations of F RNAPH, Bf124 PH and HuAdV in raw wastewater. FIB were more effectively removed than phages in both systems. Removal rates of HuAdV were similar to those of phages at the secondary treatment stage of both systems. In TF systems, HuAdV were removed at the same rate as F-RNAPH, but at lower rates than SOMPH and Bf124 PH. The findings suggest that phages (in particular SOMPH) are better indicators of the fate of viral pathogens in WWTP than existing FIB and that these organisms may have a useful role to play in future sanitation safety planning.

    更新日期:2017-11-10
  • Real-time evaluation of natural organic matter deposition processes onto model environmental surfaces
    Water Res. (IF 6.942) Pub Date : 2017-11-09
    Wenlu Li, Peng Liao, Trey Oldham, Yi Jiang, Chao Pan, Songhu Yuan, John D. Fortner

    Natural organic matter (NOM) is ubiquitous in aqueous systems and dynamically partitions onto/from environmental surfaces. However, such interfacial processes have not been uniformly quantified in situ and in real time. In this work, adsorption and deposition processes of Suwannee River humic acid (SRHA) and Suwannee River fulvic acid (SRFA), as model NOM, were evaluated for a series of environmentally relevant interfaces. Real-time, interfacial phenomenon, including deposition, release, and adlayer viscoelastic properties, were quantified over a variety of water chemistries via quartz crystal microbalance with dissipation monitoring (QCM-D). Specifically, adlayer mass and deposition rates of SRHA and SRFA were evaluated as a function of NOM concentration/molecular weight (fraction), pH, electrolyte composition (type and concentration), and collector surface type. For these, the adsorption of SRHA onto aluminum oxide (Al2O3) and polystyrene (PS) surfaces follows the Langmuir isotherm model. Rapid, near-monolayer formation of SRHA/SRFA adlayers were observed on Al2O3, hydroxyapatite (HAP), and poly (l-lysine) (PLL) surfaces, but not on PS or iron oxide (Fe3O4) surfaces. The presence of divalent cations (Ca2+/Mg2+) at relatively low concentrations (0.5–5.0 mM) significantly enhances the mass of SRHA/SRFA deposited onto the surfaces of silica (SiO2), Al2O3, and PS. Viscoelastic properties of the adsorbed layer based on the ratio of dissipation to frequency revealed a relatively unique adlayer structure for SRHA in the presence of 5.0 mM Ca2+.

    更新日期:2017-11-10
  • Predicting of ultrafiltration performances by advanced data analysis
    Water Res. (IF 6.942) Pub Date : 2017-11-09
    B. Teychene, A. Touffet, J. Baron, B. Welte, M. Joyeux, H. Gallard

    In order to optimize drinking water production operation, membrane users can use several analytical tools that help membrane fouling prediction and alleviate fouling by a proper feed water resource selection. However, during strong fouling event, membrane decision-makers still face short-term deadline to decide between different options (e.g. optimization of pretreatment or change in feed water quality). Hence, statistical approach might help to better select the most relevant analytical parameter related to fouling potential of a specific resource in order to speed-up decision taking. In this study, the physical and chemical properties and the filtration performances (at lab-scale) of five ground water resources, selected as potential resources of a large drinking production site of Paris (France), was evaluated through one year. Principal component analysis emphasizes the strong link between waters’ organic matrix and fouling propensity. Cluster analysis of filtration performances allowed classifying the water samples into three groups exhibiting strong, low and intermediate fouling. Finally, multiple linear regressions performed on all collected data indicated that strong fouling events were related to a combined increase of carbon content and protein like-substances while intermediate fouling might only be anticipated by an increase of fluorescence signal associated to protein like-substances. This study demonstrates that advanced data analysis might be a powerful tool to better manage water resources selection used for drinking water production and to forecast filtration performances in a context of water quality degradation.

    更新日期:2017-11-10
  • Evaluation of potassium ferrate as an alternative disinfectant on cyanobacteria inactivation and associated toxin fate in various waters
    Water Res. (IF 6.942) Pub Date : 2017-11-09
    Jiajia Fan, Bo-Hung Lin, Che-Wei Chang, Yuqing Zhang, Tsair-Fuh Lin

    Potassium ferrate (K2FeO4) is an effective oxidant that may be used as a pre- or post-oxidant in the purification of source water with cyanobacterial issues. To provide a better basis for the application of this oxidant during water treatment processes, the impacts of K2FeO4 on the cell viability of Microcystis aeruginosa and the fate of associated microcystins (MCs) were investigated in various water matrices. The results showed that a water matrix can significantly affect the effectiveness of K2FeO4 on cyanobacteria inactivation. 10 mg L−1 K2FeO4 induced significant cell lysis of M. aeruginosa in Ran Yi Tan Reservoir (RYTR) water while the membrane integrity was relatively unaffected in ASM-1 media and Cheng Kung Lake (CKL) water. The reduced efficiency of K2FeO4 oxidation may be attributed to the manganese (Mn2+) and organic matter (Ethylenediaminetetraacetic acid, EDTA) in the ASM-1 media and high concentrations of natural organic matters (NOMs) in the CKL water. A delayed Chick-Watson model was applied to simulate the experimental data for cyanobacterial cell rupture, and the cell lysis rates of the M. aeruginosa samples were determined to be 128-242 M−1 s−1 (mol L−1 s−1). Generally, no significant increases in extracellular MCs were observed in the three different waters, even in the RYTR water where the membrane integrity of the cyanobacterial cells was severely disrupted. Therefore, K2FeO4 could be a potential pre-oxidant to enhance subsequent treatments for cyanobacteria removal without affecting the cell integrity, or could serve as a post-oxidant to inactivate cyanobacterial cells and degrade MCs effectively, depending on the specific water matrix.

    更新日期:2017-11-10
  • Recovery of water and minerals from shale gas produced water by membrane distillation crystallization
    Water Res. (IF 6.942) Pub Date : 2017-11-08
    Junghyun Kim, Jungwon Kim, Seungkwan Hong

    Shale gas produced water (SGPW) treatment imposes greater technical challenges because of its high concentration of various contaminants. Membrane distillation crystallization (MDC) has a great potential to manage SGPW since it is capable of recovering both water and minerals at high rates, up to near a zero liquid discharge (ZLD) condition. To evaluate the feasibility of MDC for SGPW treatment, MDC performance indicators, such as water recovery rate, solid production rate (SPR) and specific energy consumption (SEC), were systematically investigated, to our knowledge for the first time, by using actual SGPW from Eagle Ford Shale (USA). The main operating parameters including feed cross-flow velocity (CFV) and crystallization temperature (TCr) were optimized by performing a series of MDC experiments. The results reported that water and minerals were effectively recovered with 84% of recovery rate and 2.72 kg/m2day of SPR under respective optimal operating conditions. Furthermore, the scale mechanism was firstly identified as limiting factor for MDC performance degradation. Lastly, SEC of MDC was estimated to be as low as 28.2 kWh/m3 under ideal optimal operating conditions. Our experimental observations demonstrated that MDC could sustainably and effectively recover water and mineral with low energy consumption from SGPW by optimizing operating condition.

    更新日期:2017-11-10
  • An improved protocol for extracting extracellular polymeric substances from granular filter media
    Water Res. (IF 6.942) Pub Date : 2017-11-08
    Sarah E. Keithley, Mary Jo Kirisits

    Extracellular polymeric substances (EPS) are an important parameter in drinking-water biofilters, and, to date, this is the first study to compare protocols from the literature for extracting EPS from granular filter media. Five extraction protocols were compared, and one was improved by varying the type of initial physical treatment and the shaking intensity, temperature, and time of incubation. Extracting EPS from granular filter media in triplicate by combining 2 g (wet weight) of filter media with 10 mL of extraction buffer (10 mM Tris, 10 mM EDTA, 2.5% NaCl, pH 8), vortexing for 1 min, and incubating for 4 h at 35 °C with shaking at 200 rpm yielded significantly higher EPS polysaccharide and/or protein concentrations than did protocols from the literature. This improved protocol extracted a significant fraction of the biofilm attached to sand but was less effective on biofilm attached to anthracite or granular activated carbon (GAC). A survey of 11 full-scale biofilters from the U.S. and Canada revealed that EPS polysaccharide and protein concentrations can vary over one order of magnitude, from 0.02 to 0.60 mg glucose/g total solids (TS) and 0.27–3.38 mg bovine serum albumin/g TS, respectively. Backwashing significantly lowered the biomass and EPS polysaccharide concentrations, but the majority of the biofilm remained attached to the filter media after backwashing, as expected. The fraction of EPS polysaccharides and proteins removed during backwashing did not differ between anthracite and GAC biofilters. The improved EPS extraction protocol can be utilized to investigate the role of EPS in biofilter performance.

    更新日期:2017-11-10
  • Silver nanoparticles stimulate the proliferation of sulfate reducing bacterium Desulfovibrio vulgaris
    Water Res. (IF 6.942) Pub Date : 2017-11-08
    Zhaoyu Chen, Ji Lu, Shu-Hong Gao, Min Jin, Philip L. Bond, Ping Yang, Zhiguo Yuan, Jianhua Guo

    The intensive use of silver nanoparticles (AgNPs) in cosmetics and textiles causes their release into sewer networks of urban water systems. Although a few studies have investigated antimicrobial activities of nanoparticles against environmental bacteria, little is known about potential impacts of the released AgNPs on sulfate reducing bacteria in sewers. Here, we investigated the effect of AgNPs on Desulfovibrio vulgaris Hidenborough (D. vulgaris), a typical sulfate-reducing bacterium (SRB) in sewer systems. We found AgNPs stimulated the proliferation of D. vulgaris, rather than exerting inhibitory or biocidal effects. Based on flow cytometer detections, both the cell growth rate and the viable cell ratio of D. vulgaris increased during exposure to AgNPs at concentrations of up to 100 mg/L. The growth stimulation was dependent on the AgNP concentration. These results imply that the presence of AgNPs in sewage may affect SRB abundance in sewer networks. Our findings also shed new lights on the interactions of nanoparticles and bacteria.

    更新日期:2017-11-10
  • Transport of iron nanoparticles through natural discrete fractures
    Water Res. (IF 6.942) Pub Date : 2017-11-07
    Meirav Cohen, Noam Weisbrod

    The transport of nano scale iron particles (NIP) in fractures is of concern for remediation of both fractured aquifers and porous aquifers when hydro-fracking and flow in preferential pathways takes place. In this study the transport of various NIP in a natural discrete fractured chalk core was investigated and their mass recoveries calculated. Four different types of NIP were tested and characterized in two ionic strength (IS) solutions at a particle concentration of 100–200 mg/l. The effect of IS, stability (sedimentation rate), particle size, solution viscosity and stabilizer were studied. NIP stability ranged from 1 to 100% following 120 min of stability tests and recoveries ranged from about 6 to 69%. The stabilizer type and concentration were shown to have significant role in NIP recoveries, especially at increased IS. It was evident that gravitational stability is the most crucial factor dominating transport of NIP. Accordingly, stability tests were shown to be a reliable indicator of NIP mobility. The high recoveries of some NIP tested, combined with the lack of clogging effect illustrates the enhanced mobility of NIP in fractures. The wide range of recoveries indicates NIP transport manipulation potential in such media. We therefore suggest that application of NIP in contaminated fractures has considerable potential as a remediation measure. In order to achieve NIP distribution in the aquifer while avoiding leakage to the environment, NIP stabilizer concentration should be adjusted according to the site-specific hydrogeochemical properties of the contaminated media.

    更新日期:2017-11-10
  • The feasibility of nanofiltration membrane bioreactor (NF-MBR)+reverse osmosis (RO) process for water reclamation: Comparison with ultrafiltration membrane bioreactor (UF-MBR)+RO process
    Water Res. (IF 6.942) Pub Date : 2017-11-07
    Ming Feng Tay, Chang Liu, Emile R. Cornelissen, Bing Wu, Tzyy Haur Chong

    This study examines the feasibility of a novel nanofiltration membrane bioreactor (NF-MBR) followed by reverse osmosis (RO) process for water reclamation at 90% recovery and using an ultrafiltration MBR (UF-MBR)+RO as baseline for comparison. Both MBRs adopted the same external hollow fiber membrane configurations and operating conditions. The collected permeates of the MBRs were subsequently fed to the respective RO systems. The results showed that the NF-MBR (operated at a constant flux of 10 L/m2h) achieved superior MBR permeate quality due to enhanced biodegradation and high rejection capacity of the NF membrane, leading to lower RO fouling rates (∼3.3 times) as compared to the UF-MBR. Further analysis indicated that the cake layer fouling that caused the cake-enhanced osmotic pressure (CEOP) effect contributed predominantly to the transmembrane pressure (TMP) increase in the NF-MBR, while irreversible pore fouling was the major reason for UF membrane fouling. Furthermore, it was found that the biopolymers (i.e., organics with MW > 10 kDa) were the main components present in the foulants of the NF/UF membranes and RO membranes. The analysis indicated that the NF-MBR + RO system at recovery of 90% has comparable energy consumption as the UF-MBR + RO system at recovery of 75%. Our findings proved the feasibility of the NF-MBR + RO for water reclamation at a high recovery rate.

    更新日期:2017-11-10
  • Wet biowaste digestion: ADM1 model improvement by implementation of known genera and activity of propionate oxidizing bacteria
    Water Res. (IF 6.942) Pub Date : 2017-11-07
    Frank Uhlenhut, Kathrin Schlüter, Claudia Gallert

    Anaerobic digestion of biowaste not only reduces environmental burden but also plays an important role for sustainable energy supply. For process optimization simulation based on the Anaerobic Digestion Model No. 1 (ADM1) is commonly used.The ADM1 was extended to include the known three genera of propionate oxidizing bacteria (POB) and the two routes of propionate degradation (methyl-malonyl CoA and C6-dismutation pathway). Kinetic parameters for anaerobic propionate oxidation by single strains of the three propionate oxidizing genera were determined from defined tri-cultures of the POB with hydrogenotrophic and acetotrophic methanogens and implemented into ADM1. The such improved model ADM1xpro was evaluated with operational data from a full scale wet biowaste digestion plant. Predicted amounts of biogas and composition with ADM1xpro (2201 m³ d−1, 68.1% CH4 and 31.9% CO2, respectively) correlated well with full-scale process data (2171 m³ d−1, 67.5% CH4 and 31.9% CO2).

    更新日期:2017-11-10
  • Extensive processing of sediment pore water dissolved organic matter during anoxic incubation as observed by high-field mass spectrometry (FTICR-MS)
    Water Res. (IF 6.942) Pub Date : 2017-11-07
    Juliana Valle, Michael Gonsior, Mourad Harir, Alex Enrich-Prast, Philippe Schmitt-Kopplin, David Bastviken, Ralf Conrad, Norbert Hertkorn

    Dissolved organic matter (DOM) contained in lake sediments is a carbon source for many microbial degradation processes, including aerobic and anaerobic mineralization. During anaerobic degradation, DOM is partially consumed and transformed into new molecules while the greenhouse gases methane (CH4) and carbon dioxide (CO2) are produced. In this study, we used ultrahigh resolution mass spectrometry to trace differences in the composition of solid-phase extractable (PPL resin) pore water DOM (SPE-DOM) isolated from surface sediments of three boreal lakes before and after 40 days of anoxic incubation, with concomitant determination of CH4 and CO2 evolution. CH4 and CO2 production detected by gas chromatography varied considerably among replicates and accounted for fractions of ∼2–4 × 10−4 of sedimentary organic carbon for CO2 and ∼0.8–2.4 × 10−5 for CH4. In contrast, the relative changes of key bulk parameters during incubation, such as relative proportions of molecular series, elemental ratios, average mass and unsaturation, were regularly in the percent range (1–3% for compounds decreasing and 4–10% for compounds increasing), i.e. several orders of magnitudes higher than mineralization alone. Computation of the average carbon oxidation state in CHO molecules of lake pore water DOM revealed rather non-selective large scale transformations of organic matter during incubation, with depletion of highly oxidized and of highly reduced CHO molecules, and formation of rather non-labile fulvic acid type molecules. In general, proportions of CHO compounds slightly decreased. Nearly saturated CHO and CHOS lipid-like substances declined during incubation: these rather commonplace molecules were less specific indicators of lake sediment alteration than the particular compounds, such as certain oxygenated aromatics and carboxyl-rich alicyclic acids (CRAM) found more abundant after incubation. There was a remarkable general increase in many CHNO compounds during incubation across all lakes. Differences in DOM transformation between lakes corresponded with lake size and water residence time. While in the small lake Svarttjärn, carboxyl-rich alicyclic molecules (CRAM) increased during incubation, lignin-and tannin-like compounds were enriched in the large lake Bisen, suggesting selective preservation of these rather non-labile aromatic compounds rather than recent synthesis. SPE-DOM after incubation may represent freshly synthesized compounds, leftover bulk DOM which is primarily composed of intrinsically refractory molecules and/or microbial metabolites which were not consumed in our experiments. In spite of a low fraction of the total DOM being mineralized to CO2 and CH4, the more pronounced change in molecular DOM composition during the incubation indicates that diagenetic modification of organic matter can be substantial compared to complete mineralization.

    更新日期:2017-11-10
  • Insights into arsenic retention dynamics of pleistocene aquifer sediments by in situ sorption experiments
    Water Res. (IF 6.942) Pub Date : 2017-11-07
    Harald Neidhardt, Lenny H.E. Winkel, Ralf Kaegi, Caroline Stengel, Pham T.K. Trang, Vi M. Lan, Pham H. Viet, Michael Berg

    The migration of arsenic (As) enriched groundwater into Pleistocene aquifers as a consequence of extensive groundwater abstraction represents an increasing threat to the precious water resources in Asian delta regions. Pleistocene aquifer sediments are typically rich in FeIII-(hydr)oxides and are capable to adsorb high amounts of As. This results in a pronounced accumulation of As in Pleistocene aquifers, where high As groundwater infiltrates from adjacent Holocene aquifers. However, As retention by Pleistocene aquifers over long-term time scales remains largely unknown. We studied As sorption in situ by placing natural Pleistocene sediments and pure mineral phases directly inside groundwater monitoring wells at a study site near Hanoi (Vietnam). This in situ exposure allows for constant flushing of the samples with unaltered groundwater and the establishment of undisturbed sorption equilibria similar to those in local aquifer sediments, which is not readily attainable in traditional laboratory sorption experiments. The groundwaters in our experimental wells were characterized by different As concentrations (0.01–6.63 μmol/L) and redox states, reaching from suboxic to anoxic conditions (Eh of +159 to −4 mV). Results show that adsorption is the dominant As retention mechanism, independent from the respective groundwater chemistry (i.e. concentrations of dissolved P, HCO3− and Si). Whilst most of the As sorbed within the first week, sorption further increased slowly but consistently by 6–189%, respectively, within six months. Hence, the As sorption behavior of Pleistocene aquifer sediments should be determined over longer periods to avoid an underestimation of the As sorption capacity. Accompanying desorption experiments revealed that about 51% of the sorbed As was remobilized within six months when exposed to low As groundwater. We therefore conclude that a considerable proportion of the As accumulated in the aquifer sediments is prone to remobilization once the As concentrations in migrating groundwater decline. Remobilization of As should be considered in local water management plans to avoid contamination of precious groundwater resources with this As legacy.

    更新日期:2017-11-10
  • Effect of TiO2 and CeO2 nanoparticles on the metabolic activity of surficial sediment microbial communities based on oxygen microelectrodes and high-throughput sequencing
    Water Res. (IF 6.942) Pub Date : 2017-11-07
    Lingzhan Miao, Peifang Wang, Chao Wang, Jun Hou, Yu Yao, Jun Liu, Bowen Lv, Yangyang Yang, Guoxiang You, Yi Xu, Zhilin Liu, Songqi Liu

    Environmental concerns regarding the potential ecological risks of metallic oxide nanoparticles (MNPs) in aquatic ecosystems are increasing; sediment is considered a sink for these MNPs. Although several studies have studied the potential impact of MNPs on microbial communities in freshwater and estuarine sediments, limited information is available regarding the influence of MNPs on the metabolic activity of surficial sediment microbial communities and related biogeochemical conditions. To address these issues, a microcosm approach was established to study the metabolic response of surficial sediment microbial communities to a single addition of TiO2 or CeO2 NPs (5 mg/L) using oxygen microelectrodes, enzyme activity measurements, and high-throughput sequencing. Rapid sedimentation of MNPs (regardless of NP type) was observed in freshwater samples, and most (up to 85%) accumulated in surface sediments (<5 mm). Microelectrode profile measurements in pre-incubated sediments treated with MNPs showed that the oxygen concentration decreased at a slower rate with increasing sediment depth compared to that in untreated controls. Biological oxygen consumption in the uppermost sediment layer (0–1500 μm) was significantly inhibited by MNPs, as calculated from steady-state microprofiles, with CeO2 NPs resulting in enhanced acute toxicity than TiO2 NPs. High-throughput sequencing showed that MNP exposure increased the bacterial diversity and altered the bacterial community structure, regardless of NP type. The abundance of three dominant bacterial genera, Methylotenera, Cytophagceae_uncultured (classified as an aerobic bacterium), and Cyanobacteria_norank (a facultative bacterium), was markedly reduced by MNPs, which was primarily responsible for inhibiting microbial-mediated oxygen consumption in surficial sediments. In summary, short-term exposure to MNPs negatively affected the metabolic activity of benthic microbial communities, which could influence the biogeochemical functions along the sediment-water interface.

    更新日期:2017-11-10
  • Elimination of chlorine-refractory carbamazepine by breakpoint chlorination: Reactive species and oxidation byproducts
    Water Res. (IF 6.942) Pub Date : 2017-11-07
    Wen-Long Wang, Qian-Yuan Wu, Ye Du, Nan Huang, Hong-Ying Hu

    Breakpoint chlorination can be commonly observed in the chlorination of water treatments when ammonia is present. In this study, it was found that breakpoint chlorination can remarkably eliminate a ubiquitous and chlorine-refractory micropollutant, carbamazepine (CBZ), with the removal of 72% at neutral condition. At neutral pH, low CBZ elimination was observed at a chlorine/ammonia molar ratio (Cl/N) of 1.0 and higher CBZ elimination was observed as Cl/N ratio increased from 1.0 to 1.6 (breakpoint), indicating that CBZ elimination was closely related to the generation and decomposition of chloramines. The chloramines generation and decomposition rates were affected by the pH, so that the CBZ elimination rate was highest at pH 7.0 and lower in acidic and basic solutions (pH 5.5 and pH 9.5, respectively). The CBZ elimination at pH 7.0 was 72.4% after 10 min of breakpoint chlorination, while reaction times about 30 min and 60 min were required to achieve the same elimination at pH 5.5 and pH 9.5, respectively. Breakpoint chlorination of CBZ was strongly suppressed by radical scavenger tBuOH and moderately suppressed by N2 purging, the inhibiting ratios being 87.7% and 27.8% at breakpoint, respectively. Electron spin resonance experiments suggested that unidentified radicals were generated by breakpoint chlorination. The <img border="0" alt="radical dot" src="https://cdn.els-cdn.com/sd/entities/rad">OH and unidentified radical species contributions to CBZ elimination were <23.7% and >76.3%, respectively, when a pseudo steady state breakpoint chlorination was performed in a microinjection system with nitrobenzene as <img border="0" alt="radical dot" src="https://cdn.els-cdn.com/sd/entities/rad">OH probe. Although CBZ were efficiently eliminated, breakpoint chlorination of CBZ generated adsorbable organic chlorine. The cytotoxicity of the CBZ solution was therefore increased by breakpoint chlorination, suggesting that biological risk caused by the breakpoint chlorination of micropollutants should be taken into consideration.

    更新日期:2017-11-10
  • Slowly biodegradable organic compounds impact the biostability of non-chlorinated drinking water produced from surface water
    Water Res. (IF 6.942) Pub Date : 2017-11-06
    W.A.M. Hijnen, R. Schurer, J.A. Bahlman, H.A.M. Ketelaars, R. Italiaander, A. van der Wal, P.W.J.J. van der Wielen

    It is possible to distribute drinking water without a disinfectant residual when the treated water is biologically stable. The objective of this study was to determine the impact of easily and slowly biodegradable compounds on the biostability of the drinking water at three full-scale production plants which use the same surface water, and on the regrowth conditions in the related distribution systems. Easily biodegradable compounds in the drinking water was determined with AOC-P17/Nox during 2012–2015. Slowly biodegradable organic compounds measured as particulate and/or high-molecular organic carbon (PHMOC), were monitored at the inlet and after the different treatment stages of the three treatments during the same period. The results show that PHMOC (300–470 μg C L−1) was approximately 10% of the TOC in the surface water and was removed to 50–100 μg C L−1. The PHMOC in the water consisted of 40–60% of carbohydrates and 10% of proteins. A significant and strong positive correlation was observed for PHMOC concentrations and two recently introduced bioassay methods for slowly biodegradable compounds (AOC-A3 and biomass production potential, BPC14). Moreover, these three parameters in the biological active carbon effluent (BACF) of the three plants showed a positive correlation with regrowth in the drinking water distribution system, which was assessed with Aeromonas, heterotrophic plate counts, coliforms and large invertebrates. In contrast, the AOC-P17/Nox concentrations did not correlate with these regrowth parameters. We therefore conclude that slowly biodegradable compounds in the treated water from these treatment plants seem to have a greater impact on regrowth in the distribution system than easily biodegradable compounds.

    更新日期:2017-11-10
  • Variations of moisture and organics in activated sludge during Fe0/S2O82− conditioning–horizontal electro-dewatering process
    Water Res. (IF 6.942) Pub Date : 2017-11-06
    Haoxuan Li, Yili Wang, Huai-Li Zheng

    The feasibility of using Fe0/S2O82− conditioning (zero valence iron (ZVI)/persulfate (ps)) integrated with horizontal electro-dewatering (HED) to improve the dewaterability of activated sludge (AS) was evaluated. The removal and migration of free and bound water in the ZVI/ps–HED process were determined, along with the organic matter migration between the solid and liquid phases of AS biosolids. Results showed that the optimum conditioning dosages were determined as 0.35 g ZVI/g dry solids (DS) and 0.15 g ps/g DS on the basis of capillary suction time variation. The lowest final water content (WC) of 83.67% in AS occurred after the HED treatment at 40 V and 120 min as determined using the response surface methodology. Despite the disruption of AS flocs and microbial cells through <img height="15" border="0" style="vertical-align:bottom" width="30" alt="View the MathML source" title="View the MathML source" src="http://origin-ars.els-cdn.com/content/image/1-s2.0-S0043135417309223-si1.gif">SO4−· oxidation during the ZVI/ps conditioning, the particle size and mass fractal dimension of the AS flocs remained relatively stable as the zeta potential increased from −8.5 mV to −4.6 mV. The coagulation of Fe3+ from the oxidation of Fe2+ by ps contributed to the relatively stable condition, which favored the subsequent momentum of the electroosmotic flow. Moreover, the ZVI/ps conditioning decreased the bound water content (BWC, from 1.83 g/g DS to 1.38 g/g DS) and increased the free water content (FWC, from 60.27 g/g DS to 60.91 g/g DS), indicating a transformation from free water to bound water. After the ZVI/ps–HED process, the FWC and BWC were removed significantly with ratios of 96.32% and 79.78%, respectively. Along with water removal through the ZVI/ps–HED process, the organic matter in the supernatant/filtrate initially increased and further rose at the HED stage. The analysis of the extracellular polymeric substance (EPS) content showed that the proteins (PNs) and polysaccharides (PSs) at the liquid and solid phases decreased due to oxidative degradation. Furthermore, the ZVI/ps stage significantly reduced the PNs content of slime to 57.22%, the PSs content of EPS to 68.50%, and the PN-like substances in the slime and tightly bound EPS to 74.90% and 52.47%, respectively. In addition, the WC of AS correlated with the contents of PN and microbial by-product-like material in slime, as well as tryptophan in TB-EPS, and the low EPS content in AS indicated good dewaterability. Thus, ZVI/ps should be selected as a pretreatment prior to HED.

    更新日期:2017-11-10
  • Analysis of microplastics in water by micro-Raman spectroscopy: Release of plastic particles from different packaging into mineral water
    Water Res. (IF 6.942) Pub Date : 2017-11-06
    Darena Schymanski, Christophe Goldbeck, Hans-Ulrich Humpf, Peter Fürst

    Microplastics are anthropogenic contaminants which have been found in oceans, lakes and rivers. Investigations focusing on drinking water are rare and studies have mainly been using micro-Fourier Transform Infrared Spectroscopy (μ-FT-IR). A major limitation of this technique is its inability to detect particles smaller than 20 μm. However, micro-Raman spectroscopy is capable of detecting even smaller particle sizes. Therefore, we show that this technique, which was used in this study, is particularly useful in detecting microplastics in drinking water where particle sizes are in the low micrometer range. In our study, we compared the results from drinking water distributed in plastic bottles, glass bottles and beverage cartons.We tested the microplastic content of water from 22 different returnable and single-use plastic bottles, 3 beverage cartons and 9 glass bottles obtained from grocery stores in Germany. Small (–50-500 μm) and very small (1–50 μm) microplastic fragments were found in every type of water. Interestingly, almost 80% of all microplastic particles found had a particle size between 5 and 20 μm and were therefore not detectable by the analytical techniques used in previous studies. The average microplastics content was 118 ± 88 particles/l in returnable, but only 14 ± 14 particles/l in single-use plastic bottles. The microplastics content in the beverage cartons was only 11 ± 8 particles/l. Contrary to our assumptions we found high amounts of plastic particles in some of the glass bottled waters (range 0–253 particles/l, mean 50 ± 52 particles/l). A statistically significant difference from the blank value (14 ± 13) to the investigated packaging types could only be shown comparing to the returnable bottles (p < 0.05).Most of the particles in water from returnable plastic bottles were identified as consisting of polyester (primary polyethylene terephthalate PET, 84%) and polypropylene (PP; 7%). This is not surprising since the bottles are made of PET and the caps are made of PP. In water from single-use plastic bottles only a few micro-PET-particles have been found. In the water from beverage cartons and also from glass bottles, microplastic particles other than PET were found, for example polyethylene or polyolefins. This can be explained by the fact that beverage cartons are coated with polyethylene foils and caps are treated with lubricants. Therefore, these findings indicate that the packaging itself may release microparticles. The main fraction of the microplastic particles identified are of very small size with dimensions less than 20 μm, which is not detectable with the μ-FT-IR technique used in previous studies.

    更新日期:2017-11-10
  • Physicochemical transformation of Fe/Ni bimetallic nanoparticles during aging in simulated groundwater and the consequent effect on contaminant removal
    Water Res. (IF 6.942) Pub Date : 2017-11-04
    Haoran Dong, Zhao Jiang, Junmin Deng, Cong Zhang, Yujun Cheng, Kunjie Hou, Lihua Zhang, Lin Tang, Guangming Zeng
    更新日期:2017-11-05
  • Modeling the transport of sodium dodecyl benzene sulfonate in riverine sediment in the presence of multi-walled carbon nanotubes
    Water Res. (IF 6.942) Pub Date : 2017-11-04
    Biao Song, Piao Xu, Guangming Zeng, Jilai Gong, Xiaoxiao Wang, Jin Yan, Shengfan Wang, Peng Zhang, Weicheng Cao, Shujing Ye
    更新日期:2017-11-05
  • The impact of operational strategies on the performance of a photo-EBPR system
    Water Res. (IF 6.942) Pub Date : 2017-11-04
    V.C.F. Carvalho, E.B. Freitas, P.J. Silva, J.C. Fradinho, M.A.M. Reis, A. Oehmen
    更新日期:2017-11-05
  • Evidence of co-metabolic bentazone transformation by methanotrophic enrichment from a groundwater-fed rapid sand filter
    Water Res. (IF 6.942) Pub Date : 2017-11-03
    Mathilde J. Hedegaard, Hélène Deliniere, Carsten Prasse, Arnaud Dechesne, Barth F. Smets, Hans-Jørgen Albrechtsen
    更新日期:2017-11-05
  • Towards improved accuracy in modeling aeration efficiency through understanding bubble size distribution dynamics
    Water Res. (IF 6.942) Pub Date : 2017-11-03
    Andreia Amaral, Giacomo Bellandi, Usman Rehman, Ramiro Neves, Youri Amerlinck, Ingmar Nopens
    更新日期:2017-11-05
  • 更新日期:2017-11-05
  • Modelling the long-term effect of wastewater compositions on maximum sulfide and methane production rates of sewer biofilm
    Water Res. (IF 6.942) Pub Date : 2017-11-03
    Jing Sun, Bing-Jie Ni, Keshab Raj Sharma, Qilin Wang, Shihu Hu, Zhiguo Yuan
    更新日期:2017-11-05
  • Low voltage electric potential as a driving force to hinder biofouling in self-supporting carbon nanotube membranes
    Water Res. (IF 6.942) Pub Date : 2017-11-03
    Chidambaram Thamaraiselvan, Avner Ronen, Sofia Lerman, Moran Balaish, Yair Ein-Eli, Carlos G. Dosoretz
    更新日期:2017-11-05
  • Development and modelling of a steel slag filter effluent neutralization process with CO2-enriched air from an upstream bioprocess
    Water Res. (IF 6.942) Pub Date : 2017-11-03
    Patricia Bove, Dominique Claveau-Mallet, Étienne Boutet, Félix Lida, Yves Comeau
    更新日期:2017-11-05
  • Uranium in groundwater – A synopsis based on a large hydrogeochemical data set
    Water Res. (IF 6.942) Pub Date : 2017-11-02
    Thomas Riedel, Christine Kübeck

    Most of the knowledge on the occurrence of Uranium (U) in groundwater comes from in-situ manipulation experiments in the field, computational modelling studies or from laboratory analyses where individual processes of U mobilization were studied in isolation. Because of Uranium's vital redox chemistry it interacts, often simultaneously, with many other element cycles (e.g., sulfur, carbon, iron, and manganese) making it difficult to predict U concentrations in natural environments. For the present study a large data set was analyzed to predict the occurrence of U in groundwater from basic hydrochemistry. The data set consists of more than 8000 chemical groundwater analyses (including Uranium concentrations) from more than 2000 sampling locations.A strong relation between U concentrations and electric conductivity as well as alkalinity was observed, suggesting that weathering of geogenic source material and desorption from mineral surfaces is the principle mechanism of U release. Except for aquifers with strongly reducing conditions this process leads to a slow but continuous accumulation of U in groundwater in most cases. Importantly, the occurrence of U is modulated by the prevailing redox conditions in an aquifer. Uranium concentrations were moderate under oxic conditions and highest under Manganese-und Nitrate-reducing conditions (heterotrophic as wells as autotrophic nitrate reduction). Only in iron- and sulfate-reducing groundwater the probability of U concentrations above 1 μg l−1 was virtually zero, as these ground waters act as U sinks.The combination of mineral weathering (especially carbonates) with mobilization of U under manganese and nitrate reducing conditions results in the highest risk of detecting U. In contrast, a low risk is associated with low pH (<7) and low mineralization of groundwater, which is the case in granitic catchments, for example. Our results further provide evidence, that agricultural practices such as liming, fertilizer inputs and irrigation influence the occurrence of U in groundwater in multiple ways. Accurate management of aquifers underlying farmland will therefore become more and more important in the future. In summary, we find that the vulnerability of an aquifer to elevated U concentrations cannot be explained by a single factor. This complicates affords to target elevated U concentrations in groundwaters that are abstracted for drinking water production.

    更新日期:2017-11-05
  • Electrolytic and electro-irradiated technologies for the removal of chloramphenicol in synthetic urine with diamond anodes
    Water Res. (IF 6.942) Pub Date : 2017-11-01
    Salvador Cotillas, Engracia Lacasa, Cristina Sáez, Pablo Cañizares, Manuel A. Rodrigo
    更新日期:2017-11-01
  • Development of Genetic Programming-Based Model for Predicting Oyster Norovirus Outbreak Risks
    Water Res. (IF 6.942) Pub Date : 2017-11-01
    Shima Shamkhali Chenar, Zhiqiang Deng
    更新日期:2017-11-01
  • A human fecal contamination score for ranking recreational sites using the HF183/BacR287 quantitative real-time PCR method
    Water Res. (IF 6.942) Pub Date : 2017-10-31
    Yiping Cao, Mano Sivaganesan, Catherine A. Kelty, Dan Wang, Alexandria B. Boehm, John F. Griffith, Stephen B. Weisberg, Orin C. Shanks
    更新日期:2017-11-01
  • Impacts of water quality on the corrosion of cast iron pipes for water distribution and proposed source water switching strategy
    Water Res. (IF 6.942) Pub Date : 2017-10-31
    Jun Hu, Huiyu Dong, Wencui Ling, Jiuhui Qu, Zhimin Qiang
    更新日期:2017-10-31
  • Modeling sewage leakage and transport in carbonate aquifer using carbamazepine as an indicator
    Water Res. (IF 6.942) Pub Date : 2017-10-31
    Noam Zach Dvory, Michael Kuznetsov, Yakov Livshitz, Guy Gasser, Irena Pankratov, Ovadia Lev, Eilon Adar, Alexander Yakirevich
    更新日期:2017-10-31
  • Faradaic reactions in capacitive deionization (CDI) - problems and possibilities: a review
    Water Res. (IF 6.942) Pub Date : 2017-10-31
    Changyong Zhang, Di He, Jinxing Ma, Wangwang Tang, T. David Waite
    更新日期:2017-10-31
  • Microbial transcript and metabolome analysis uncover discrepant metabolic pathways in autotrophic and mixotrophic anammox consortia
    Water Res. (IF 6.942) Pub Date : 2017-10-31
    Ying Feng, Yunpeng Zhao, Yongzhao Guo, Sitong Liu
    更新日期:2017-10-31
  • Potent removal of cyanobacteria with controlled release of toxic secondary metabolites by a titanium xerogel coagulant
    Water Res. (IF 6.942) Pub Date : 2017-10-30
    Xiaomeng Wang, Xin Wang, Zhongbo Wei, Shujuan Zhang
    更新日期:2017-10-31
  • Biohydrogen production at pH below 3.0: Is it possible?
    Water Res. (IF 6.942) Pub Date : 2017-10-30
    V.T. Mota, A.D.N. Ferraz-Júnior, E. Trably, M. Zaiat
    更新日期:2017-10-31
  • Validation of a multi-phase plant-wide model for the description of the aeration process in a WWTP
    Water Res. (IF 6.942) Pub Date : 2017-10-30
    I. Lizarralde, T. Fernández-Arévalo, S. Beltrán, E. Ayesa, P. Grau
    更新日期:2017-10-30
  • Stable long-term operation of an upflow anammox sludge bed reactor at mainstream conditions
    Water Res. (IF 6.942) Pub Date : 2017-10-30
    Clara Reino, María Eugenia Suárez-Ojeda, Julio Pérez, Julián Carreraz
    更新日期:2017-10-30
  • Natural attenuation of chlorinated ethenes in hyporheic zones: a review of key biogeochemical processes and in-situ transformation potential
    Water Res. (IF 6.942) Pub Date : 2017-10-30
    John J. Weatherill, Siavash Atashgahi, Uwe Schneidewind, Stefan Krause, Sami Ullah, Nigel Cassidy, Michael O. Rivett
    更新日期:2017-10-30
  • Simulation of photoreactive transients and of photochemical transformation of organic pollutants in sunlit boreal lakes across 14 degrees of latitude
    Water Res. (IF 6.942) Pub Date : 2017-10-30
    Birgit Koehler, Francesco Barsotti, Marco Minella, Tomas Landelius, Claudio Minero, Lars J. Tranvik, Davide Vione
    更新日期:2017-10-30
  • Degradation of perfluorinated compounds by sulfate radicals – New mechanistic aspects and economical considerations
    Water Res. (IF 6.942) Pub Date : 2017-10-30
    Holger V. Lutze, Julia Brekenfeld, Sergej Naumov, Clemens von Sonntag, Torsten C. Schmidt

    Perfluorinated organic compounds (PFC) are an important group of pollutants, which are difficult to be degraded in conventional water treatment. Even hydroxyl radical based processes are not capable to degrade these compounds. Sulfate radicals can oxidize a group of PFCA, i.e., perfluorinated carboxylic (PFCAs) acids. However, information in literature on kinetics and reaction mechanism is largely based on model simulations which are prone to errors. The present study provides mechanistic insights based on product formation, material balances, competition kinetics experiments and quantum chemical calculations. Furthermore, energy requirements for sulfate radical based degradation of PFCA is evaluated in the present study. PFCAs can be partly mineralized in chain reactions initiated by SO4●─. The perfluorinated acetic acid, propionic acid, and butanoic acid are completely degraded in a primary reaction with sulfate radicals. In case of PFCA with chain length of > 4 carbons low yields of PFCA products were observed. Regarding reaction kinetics sulfate radicals react very slow with PFCAs (≈ 104 M-1 s-1). Thus, the energy demand required for generation of SO4●─ by photolysis of S2O82─ (UV/S2O82-) is very high. A 90 % degradation of a PFCA by UV/S2O82- was estimated to be 55 kWh m-3 in pure water.

    更新日期:2017-10-30
  • Effects of roughness and permeability on solute transfer at the sediment water interface
    Water Res. (IF 6.942) Pub Date : 2017-10-29
    Xu Han, Hongwei Fang, Guojian He, Danny Reible
    更新日期:2017-10-30
  • 更新日期:2017-10-28
  • Metagenomic characterization of biofilter microbial communities in a full-scale drinking water treatment plant
    Water Res. (IF 6.942) Pub Date : 2017-10-28
    Seungdae Oh, Frederik Hammes, Wen-Tso Liu
    更新日期:2017-10-28
  • Direct Potable Reuse Microbial Risk Assessment Methodology: Sensitivity Analysis and Application to State Log Credit Allocations
    Water Res. (IF 6.942) Pub Date : 2017-10-27
    Jeffrey A. Soller, Sorina E. Eftim, Sharon P. Nappier

    Understanding pathogen risks is a critically important consideration in the design of water treatment, particularly for potable reuse projects. As an extension to our published microbial risk assessment methodology to estimate infection risks associated with Direct Potable Reuse (DPR) treatment train unit process combinations, herein, we (1) provide an updated compilation of pathogen density data in raw wastewater and dose-response models; (2) conduct a series of sensitivity analyses to consider potential risk implications using updated data; (3) evaluate the risks associated with log credit allocations in the United States; and (4) identify reference pathogen reductions needed to consistently meet currently applied benchmark risk levels. Sensitivity analyses illustrated changes in cumulative annual risks estimates, the significance of which depends on the pathogen group driving the risk for a given treatment train. For example, updates to norovirus (NoV) raw wastewater values and use of a NoV dose-response approach, capturing the full range of uncertainty, increased risks associated with one of the treatment trains evaluated, but not the other. Additionally, compared to traditional log-credit allocation approaches, our results indicate that the risk methodology provides more nuanced information about how consistently public health benchmarks are achieved. Our results indicate that viruses need to be reduced by 14 logs or more to consistently achieve currently applied benchmark levels of protection associated with DPR. The refined methodology, updated model inputs, and log credit allocation comparisons will be useful to regulators considering DPR projects and design engineers as they consider which unit treatment processes should be employed for particular projects.

    更新日期:2017-10-27
  • Population density controls on microbial pollution across the Ganga catchment
    Water Res. (IF 6.942) Pub Date : 2017-10-27
    D.G. Milledge, S.K. Gurjar, J.T. Bunce, V. Tare, R. Sinha, P.E. Carbonneau

    For millions of people worldwide, sewage-polluted surface waters threaten water security, food security and human health. Yet the extent of the problem and its causes are poorly understood. Given rapid widespread global urbanisation, the impact of urban versus rural populations is particularly important but unknown. Exploiting previously unpublished archival data for the Ganga (Ganges) catchment, we find a strong non-linear relationship between upstream population density and microbial pollution, and predict that these river systems would fail faecal coliform standards for irrigation waters available to 79% of the catchment’s 500 million inhabitants. Overall, this work shows that microbial pollution is conditioned by the continental-scale network structure of rivers, compounded by the location of cities whose growing populations contribute c. 100 times more microbial pollutants per capita than their rural counterparts.

    更新日期:2017-10-27
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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