Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Bing Han , Man Zhang , Dongye Zhao , Yucheng Feng Manganese oxide (MnO 2 ) was reported to be effective for degrading aqueous pharmaceutical chemicals. However, little is known about its potential use for degrading soil-sorbed contaminants. To bridge this knowledge gap, we synthesized, for the first time, a class of stabilized MnO 2 nanoparticles using carboxymethyl celluloses (CMC) as a stabilizer, and tested their effectiveness for degrading aqueous and soil-sorbed estradiol. The most desired particles (highest reactivity and soil deliverability) were obtained at a CMC/MnO 2 molar ratio of 1.39 × 10 −3 , which yielded a mean hydrodynamic size of 39.5 nm and a narrow size distribution (SD = 0.8 nm). While non-stabilized MnO 2 particles rapidly aggregated and were not transportable through a soil column, CMC-stabilized nanoparticles remained fully dispersed in water and were soil deliverable. At typical aquatic pH (6–7), CMC-stabilized MnO 2 exhibited faster degradation kinetics for oxidation of 17β-estradiol than non-stabilized MnO 2 . The reactivity advantage becomes more evident when used for treating soil-sorbed estradiol owing to the ability of CMC to complex with metal ions and prevent the reactive sites from binding with inhibitive soil components. A retarded first-order rate model was able to interpret the oxidation kinetics for CMC-stabilized MnO 2 . When used for degrading soil-sorbed estradiol, several factors may inhibit the oxidation effectiveness, including desorption rate, soil–MnO 2 interactions, and soil-released metals and reductants. CMC-stabilized MnO 2 nanoparticles hold the potential for facilitating in situ oxidative degradation of various emerging contaminants in soil and groundwater. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Yoana Del-Pilar-Ruso , Elena Martinez-Garcia , Francisca Giménez-Casalduero , Angel Loya-Fernández , Luis Miguel Ferrero-Vicente , Candela Marco-Méndez , Jose Antonio de-la-Ossa-Carretero , José Luis Sánchez-Lizaso In many regions, seawater desalination is a growing industry that has its impact on benthic communities. This study analyses the effect on benthic communities of a mitigation measure applied to a brine discharge, using polychaete assemblages as indicator. An eight-year study was conducted at San Pedro del Pinatar (SE Spain) establishing a grid of 12 sites at a depth range of 29–38 m during autumn. Brine discharge started in 2006 and produced a significant decrease in abundance, richness and diversity of polychaete families at the location closest to the discharge, where salinity reached 49. In 2010, a diffuser was deployed at the end of the pipeline in order to increase the mixing, to reduce the impact on benthic communities. After implementation of this mitigation measure, the salinity measured close to discharge was less than 38.5 and a significant recovery in polychaete richness and diversity was detected, to levels similar to those before the discharge. A less evident recovery in abundance was also observed, probably due to different recovery rates of polychaete families. Some families like Paraonidae and Magelonidae were more tolerant to this impact. Others like Syllidae and Capitellidae recovered quickly, although still affected by the discharge, while some families such as Sabellidae and Cirratulidae appeared to recover more slowly. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): P.-Ph. Remy , M. Etique , A.A. Hazotte , A.-S. Sergent , N. Estrade , C. Cloquet , K. Hanna , F.P.A. Jorand The kinetics of Hg II and methyl red (MR) reduction by hydroxycarbonate green rust (GR1) and by hydroxysulfate green rust (GR2) were studied in the presence of naturally occurring organic and inorganic ligands (phosphate, polyacrylic acid, bacterial cells, silicate). The reducing ability of biogenic hydroxycarbonate green rust (GR1 bio ), obtained after microbial reduction of lepidocrocite by Shewanella putrefaciens , was also investigated and compared to those of chemically synthesized GR1 and GR2 (GR1 ab and GR2 ab ). Pseudo first-order rate constants ( k obs ) of Hg II reduction (at pH 7.0, 8.2, and 9.5) and MR reduction (at pH 7.0) were determined and were normalized to the structural Fe II content of GRs ( k FeII ) and to the estimated concentration of surface Fe II sites ( k S ). The k S values ranged from 0.3 L mmol −1 min −1 to 43 L mmol −1 min −1 for the Hg reduction, and from 0.007 L mmol −1 min −1 to 3.4 L mmol −1 min −1 for the MR reduction. No significant discrepancy between GR ab and GR bio was observed in term of reactivity. However, the reduction kinetics of MR was generally slower than the Hg II reduction kinetics for all tested GRs. While a slight difference in Hg II reduction rate was noted whatever the pH values (7.0, 8.2, or 9.5), the reduction of MR was significantly affected in the presence of ligands. A decrease by a factor of 2–200, depending on the type of ligand used, was observed. These data give new insights into the reactivity of GRs in the presence of co-occurring organic and inorganic ligands, and have major implications in the characterization of contaminated systems as well as water treatment processes. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Ashok Aryal , Arumugam Sathasivan , Anna Heitz , Gang Zheng , Hamid Nikraz , Maneesha P. Ginige Biological activated carbon (BAC) and magnetic ion exchange resin (MIEX) were used to pre-treat secondary wastewater effluent (SWWE) and assessed for their capacity to reduce fouling of a nanofiltration membrane. BAC pre-treated water facilitated a lower but a steady flux while MIEX treated water resulted in a higher but a rapidly declining flux. Their combined use increased average flux from 58 to 89%. MIEX combined with BAC, in that order, was superior in reducing membrane fouling. Measurement of average Stokes radius (m) and apparent molecular weight distribution of dissolved organic matter (DOM), by nuclear magnetic resonance (NMR) and liquid chromatography organic carbon detection (LC-OCD), respectively, revealed that the microbial activity of BAC changed the nature of organic matter, probably by increasing the size of DOM molecules. BAC generally decreased the lower apparent molecular weight (LMW) fraction of dissolved organic carbon (DOC). Hence, the removal of LMW DOC and an increase of average Stokes radius (m) of DOM appeared to be important in facilitating a longer steady flux. Specifically, the combined MIEX/BAC pre-treatments appeared to target and reduce the foulants in SWWE that are largely responsible for the reduction of flux in nanofiltration membranes. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Kimberly Solon , Xavier Flores-Alsina , Christian Kazadi Mbamba , Eveline I.P. Volcke , Stephan Tait , Damien Batstone , Krist V. Gernaey , Ulf Jeppsson Plant-wide models of wastewater treatment (such as the Benchmark Simulation Model No. 2 or BSM2) are gaining popularity for use in holistic virtual studies of treatment plant control and operations. The objective of this study is to show the influence of ionic strength (as activity corrections) and ion pairing on modelling of anaerobic digestion processes in such plant-wide models of wastewater treatment. Using the BSM2 as a case study with a number of model variants and cationic load scenarios, this paper presents the effects of an improved physico-chemical description on model predictions and overall plant performance indicators, namely effluent quality index ( EQI ) and operational cost index ( OCI ). The acid-base equilibria implemented in the Anaerobic Digestion Model No. 1 (ADM1) are modified to account for non-ideal aqueous-phase chemistry. The model corrects for ionic strength via the Davies approach to consider chemical activities instead of molar concentrations. A speciation sub-routine based on a multi-dimensional Newton–Raphson (NR) iteration method is developed to address algebraic interdependencies. The model also includes ion pairs that play an important role in wastewater treatment. The paper describes: 1) how the anaerobic digester performance is affected by physico-chemical corrections; 2) the effect on pH and the anaerobic digestion products (CO 2 , CH 4 and H 2 ); and, 3) how these variations are propagated from the sludge treatment to the water line. Results at high ionic strength demonstrate that corrections to account for non-ideal conditions lead to significant differences in predicted process performance (up to 18% for effluent quality and 7% for operational cost) but that for pH prediction, activity corrections are more important than ion pairing effects. Both are likely to be required when precipitation is to be modelled. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Yiwei Ma , Suneethi Sundar , Hongkeun Park , Kartik Chandran The overarching goal of this study was to determine the role of inorganic carbon (IC) in influencing the microbial ecology, performance and nitrogen turnover by individual microbial communities of a biofilm based combined nitritation–anammox process. IC limitation was transiently imposed by reducing the IC input from 350% to 40% of the stoichiometric requirement for 40 days. The principal impact observed during IC limitation was the overgrowth of nitrite oxidizing bacteria (NOB) at the expense of anaerobic ammonia oxidizing bacteria (AMX). On the other hand, the concentrations of ammonia oxidizing bacteria (AOB) were relatively stable during the imposition of and recovery from IC limitation. The resulting dominance of NOB, in terms of their concentration and contribution to nitrite consumption over AMX, resulted, in turn, in a decrease in overall nitrogen removal from 78 ± 2.0% before IC limitation to 46 ± 2.9% during IC limitation. Upon recovery back to non-limiting IC input, it took an inordinately long time (about 57*HRT) for the N-removal to recover back to pre-limitation conditions. Even after recovery, NOB were still persistent in the biofilm and could not be washed out to pre-limitation concentrations. The emission of nitrous oxide (N 2 O) and nitric oxide (NO), likely from AOB, transiently increased in concert with transient increases in ammonia and hydroxylamine concentrations during the period of IC limitation. Therefore, an unintended consequence of IC limitation in nitritation–anammox systems can be an increase in their greenhouse gas footprint, in addition to compromised process performance. Most emphasis to date on nitritation and anammox studies has been on the nitrogen cycle. The results of this study demonstrate that the differing strategies used by AOB, NOB and AMX to compete for their preferred assimilative carbon source can also significantly influence the microbial ecology, performance and carbon footprint of such processes. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Barbara Siembida-Lösch , William B. Anderson , Yulang (Michael) Wang , Jane Bonsteel , Peter M. Huck The focus of this full-scale study was to determine the effect of ozone on biopolymer concentrations in biofiltration and ultrafiltration (UF) processes treating surface water from Lake Ontario. Ozonation was out of service for maintenance for 9 months, hence, it was possible to investigate ozone's action on biologically active carbon contactors (BACCs) and UF, in terms of biopolymer removal. Given the importance of biopolymers for fouling, this fraction was quantified using a chromatographic technique. Ozone pre-treatment was observed to positively impact the active biomass in biofilters. However, since an increase of the active biomass did not result in higher biopolymer removal, active biomass concentration cannot be a surrogate for biofiltration performance. It was evident that increasing empty bed contact time (EBCT) from 4 to 19 min only had a positive effect on biopolymer removal through BACCs when ozone was out of service. However, as a mass balance experiment showed, ozone-free operation resulted in higher deposition of biopolymers on a UF membrane and slight deterioration in its performance. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Crystal A. McCall , Katerina S. Jordan , Marc B. Habash , Kari E. Dunfield A lysimeter-based field study was done to monitor the transfer of culturable Escherichia coli , general (ALLBAC), human (Hf183) and swine (PIG-BAC-1) specific 16S rRNA Bacteroides spp. markers, nutrients and metals through soils and leachate over time following land application of a CP1/Class A as well as two CP2/Class B municipal biosolids (MBs). Hf183 markers were detected up to six days following application in soils receiving dewatered and liquid MBs, but not in leachate, suggesting their use in source tracking is better suited for recent pollution events. The CP2/Class B biosolids and swine manure contributed the highest microbial load with E. coli loads (between 2.5 and 3.7 log CFU (100 mL) −1 ) being greater than North American concentration recommendations for safe recreational water. ALLBAC persisted in soils and leachate receiving all treatments and was detected prior to amendment application demonstrating its unsuitability for identifying the presence of fecal pollution. A significant increase in NO 3 –N (for Lystek and dewatered MBs) and total-P (for dewatered and liquid MBs) in leachate was observed in plots receiving the CP1/Class A and CP2/Class B type MBs which exceeded North American guidelines, suggesting impact to surface water. Metal (As, Cd, Cr, Co, Cu, Pb, Mo, Ni, Se, Zn and Hg) transfer was negligible in soil and leachate samples receiving all treatments. This study is one of the first to examine the fate of E. coli and Bacteroides spp. markers in situ following the land application of MBs where surface runoff does not apply.

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Sungwoo Bae , Stefan Wuertz It is difficult to compare decay kinetics for genetic markers in an environmental context when they have been determined at different ambient temperatures. Therefore, we investigated the persistence of the host-associated genetic markers BacHum, BacCow and BacCan as well as the general Bacteroidales marker BacUni in both intact Bacteroidales cells and as total intracellular and extracellular marker DNA in controlled batch experiments at two temperatures using PMA-qPCR. Fecal Bacteroidales cells and DNA persisted longer at the lower temperature. Using the modified Arrhenius function to calculate decay constants for the same temperature, we then compared the decay of host-associated Bacteroidales cells and their DNA at 14°C in field-based flow-through microcosms containing human, cow, and dog feces suspended in freshwater or seawater and previously operated with an identical experimental design. The time for a 2-log reduction (T 99 ) was used to characterize host-associated Bacteroidales decay. Host-associated genetic markers as determined by qPCR had similar T 99 values in freshwater and seawater at 14°C when compared under both sunlight and dark conditions. In contrast, intact Bacteroidales cells measured by PMA-qPCR had shorter T 99 values in seawater than in freshwater. The decay constants of Bacteroidales cells were a function of physical (temperature) and chemical (salinity) parameters, suggesting that environmental parameters are key input variables for Bacteroidales survival in a predictive water quality model. Molecular markers targeting total Bacteroidales DNA were less susceptible to the variance of temperature, salinity and sunlight, implying that measurement of markers in both intact cells and DNA could enhance the predictive power of identifying fecal pollution across all aquatic environments. Monitoring Bacteroidales by qPCR alone rather than by PMA-qPCR does not always identify the contribution of recent fecal contamination because a signal may be detected that does not reflect a recent fecal event. Graphical abstract

Description: Publication date: 1 March 2015 Source: Water Research, Volume 70 Author(s): Boning Liu , David A. Reckhow The quality of water entering a distribution system may differ substantially from the quality at the point of exposure to the consumer. This study investigated temporal variations in the levels of regulated and non-regulated disinfection byproducts (DBPs) in cold and hot tap water in a home on a medium-sized municipal water system. In addition, samples were collected directly from the water plant with some being held in accordance with a simulated distribution system (SDS) test protocol. The location for this work was a system in western Massachusetts, USA that uses free chlorine as a final disinfectant. Very little short term variability of DBPs at the point of entry (POE) was observed. The concentration of DBPs in the time-variable SDS test was similar to concentrations in the cold water tap. For most DBPs, the concentrations continued to increase as the cold water tap sample was held for the time-variable SDS incubation period. However, the impact of heating on DBP levels was compound specific. For example, the concentrations of trihalomethanes (THMs), dichloroacetic acid (DCAA) and chloropicrin (CP) were substantially higher in the hot water tap than in the cold water time-variable SDS samples. In contrast, the concentration of trichloroacetic acid (TCAA) was lower in the heated hot tap water, but about equal to that observed in the cold tap water. The situation was more pronounced for dichloroacetonitrile (DCAN), bromodichloroacetic acid (BDCAA), bromochloroacetic acid (BCAA) and 1,1,1-trichloropropanone (TCP), which all showed lower concentrations in the hot water then in either of the cold water samples (instantaneous or time-variable SDS). The latter was viewed as a clear indication of thermally-induced decomposition. The ratio of unknown total organic halide (UTOX) to TOX was substantially lower in the hot tap water as the THM to TOX ratio became correspondingly larger. The results of this study show that DBP exposure in the home is not well represented by concentrations measured in cold water taps where most compliance monitoring is done. Graphical abstract