Description: Publication date: 1 August 2018 Source: Water Research, Volume 139 Author(s): Wei Ouyang, Wanxin Yang, Mats Tysklind, Yixue Xu, Chunye Lin, Xiang Gao, Zengchao Hao The formation and transportation processes of non-point source (NPS) pollution varied among the studied watersheds in the Northeastern China, so we hypothesized that the driving force behind NPS pollution followed the spatial scale effect. With a watershed outlet sedimentary flux analysis and a distributed NPS pollution loading model, we investigated the temporal dynamics of NPS and the differences in driving forces. Sediment core samples were collected from two adjacent watersheds, the smaller Abujiao watershed and the larger Naoli watershed. The natural climatic conditions, long-term variations in the distribution of land use, soil properties and tillage practices were the same in the two watersheds. The vertical distributions of total nitrogen, total phosphorus, Zn and As at 1-cm intervals in the section showed clear differences between the watersheds. There were higher concentrations of total nitrogen and total phosphorus in the larger watershed, but the heavy metals were more concentrated in the smaller watershed. Lead-210 ( 210 Pb) analyses and the constant rate of supply model provided a dated sedimentary flux, which was correlated with the corresponding yearly loading of NPS total nitrogen and total phosphorus in the two watersheds. The total phosphorus showed a stable relationship in both watersheds with an R 2 value that ranged from 0.503 to 0.682. A rose figure comparison also demonstrated that the pollutant flux in the sediment was very different in the two watersheds, which had similar territorial conditions and different hydrological patterns. Redundancy analysis further indicated that expanding paddy areas had a large impact on the sedimentary flux of nitrogen and phosphorus in the smaller watershed, but precipitation had a direct impact on NPS loading in the larger watershed. We concluded that the spatial scale effect affected the NPS pollution via the transport processes in the waterway, which was mainly influenced by branch length and drainage density.

Description: Publication date: 1 August 2018 Source: Water Research, Volume 139 Author(s): Yan Gao, Wen Zhang, Bin Gao, Wen Jia, Aijun Miao, Lin Xiao, Liuyan Yang Electrolysis combined with biochar (BC) was used in a constructed wetland to intensify nitrogen (N) and phosphorus (P) removal from wastewater simultaneously. A pilot study was conducted using an electrolysis-integrated, BC-amended, horizontal, subsurface-flow, constructed wetland (E-BHFCW). The research results showed that both electrolysis and BC substrate played important roles in the intensified, constructed wetland. The electrolysis combined BC substrate greatly enhanced the removal rates of nitrate (49.54%) and P (74.25%) when the E-BHFCW operated under the lower current density of 0.02 mA/cm 2 and an electrolysis time of 24 h. Improved N removal was accomplished with the electrochemical denitrification of iron cathodes; the autotrophic denitrification bacteria appeared to remove nitrate which was adsorbed on the BC substrate because hydrogen gas was produced by cathodes in the E-BHFCW. Less nitrate was taken directly by wetland plants and microbes. The in-situ formation of ferric ions from a sacrificial iron anode, causing P chemical sedimentation and physical adsorption, improved P removal. BC, modified by iron ions from an iron anode to adsorb the nitrate and P, was a good material to improve effluent water quality. It can also serve as a favorable microbial carrier to bio-transform nitrate to N gas. This is because there were abundant and diverse bacterial communities in the biofilm on the BC substrate in the E-BHFCW. Thus, electrolysis integrated with BC in a constructed wetland is a novel, feasible and effective technique for enhancing wastewater N and P removal. Graphical abstract

Description: Publication date: 1 August 2018 Source: Water Research, Volume 139 Author(s): Elena Villar-Navarro, Rosa M. Baena-Nogueras, Maria Paniw, José A. Perales, Pablo A. Lara-Martín Microalgae biotechnology is a promising tool for many applications, including the elimination of nutrients and other contaminants from wastewater. In this work, we measured the removal efficiency of two wastewater treatment processes: an activated-sludge based conventional process and another based on microalgae biotechnology using high-rate algae ponds (HRAPs). The latter was tested using two different configurations. In the first one, HRAPs were placed after an UASB reactor and used as a tertiary treatment to remove nutrients. In the second, the UASB reactor was disconnected so the HRAPs were directly fed with pretreated wastewater. Additional treatment was performed using dissolved air flotation (DAF). The performances of both configurations (UASB-HRAP and HRAP-DAF) were compared to that of the conventional line including primary and secondary biological treatments and operating in parallel within the same wastewater treatment plant (WWTP). Sixty-four out of 81 target PhACs were detected in the influent of the WWTP, at an average concentration of 223 μg L −1 , whereas 55 and 54 were measured in the conventional (14 μg L −1 ) and non-conventional (17 μg L −1 ) effluents. Average removal efficiencies were similar (94 vs. 92%) for both treatment lines when comparing total PhACs concentrations. The compositional patterns of the resulting effluents, however, were not, suggesting the occurrence of differential removal mechanisms depending on the chemicals and wastewater treatments considered. Highly consumed compounds such as ibuprofen and acetaminophen were predominant in the non-conventional effluent (>1 μg L −1 ), denoting lower removal than in the conventional line. On the other hand, elimination of diclofenac and some specific antibiotics and diuretics (e.g., hydrochlorothiazide) was between 15 and 50% higher using HRAPs. Overall, the efficiency of the microalgae technology removing PhACs was found to be comparable to that used in conventional WWTPs. This, combined with a higher efficiency removing nutrients, shows the potential of HRAP technology for wastewater treatment as an alternative (or addition as tertiary treatment) to more conventional approaches based on activated sludge. Graphical abstract

Description: Publication date: 1 August 2018 Source: Water Research, Volume 139 Author(s): Kam W. Tang, Sabine Flury, Dominic Vachon, César Ordóñez, Daniel F. McGinnis Chaoborus spp. (phantom midge) are prevalent in eutrophic inland waters. In Lake Soppen, Switzerland, C. flavicans larvae diurnally migrate between the methane-rich, oxygen-depleted hypolimnion and sediments, and the methane-poor, oxygen-rich epilimnion. Using a combination of experiments and system modelling, this study demonstrated that the larvae's burrowing activities in and out of the sediment perturbed the sediment and re-introduced sequestered phosphorus into the overlying water at a rate of 0.022 μg P ind −1 d −1 , thereby exacerbating internal nutrient loading in the water column. Fluxes of sediment methane and other reduced solutes enhanced by the larval bioturbation would consume oxygen and sustain the hypoxic/anoxic condition below the thermocline. In addition to increasing diffusive fluxes, migrating larvae also directly transported methane in their gas vesicles from the deep water and release it in the surface water at a rate of 0.99 nmol CH 4 ind −1 d −1 , potentially contributing to methane emission to air. As nutrient pollution and climate warming persist or worsen in the coming decades, proliferation of Chaoborus could intensify this positive feedback loop and delay lake recovery. Graphical abstract

Description: Publication date: 1 August 2018 Source: Water Research, Volume 139 Author(s): Stephan Wagner, Thorsten Hüffer, Philipp Klöckner, Maren Wehrhahn, Thilo Hofmann, Thorsten Reemtsma Tire wear particles (TWP), generated from tire material during use on roads have gained increasing attention as part of organic particulate contaminants, such as microplastic, in aquatic environments. The available information on properties and generation of TWP, analytical techniques to determine TWP, emissions, occurrence and behavior and ecotoxicological effects of TWP are reviewed with a focus on surface water as a potential receptor. TWP emissions are traffic related and contribute 5–30% to non-exhaust emissions from traffic. The mass of TWP generated is estimated at 1,327,000 t/a for the European Union, 1,120,000 t/a for the United States and 133,000 t/a for Germany. For Germany, this is equivalent to four times the amount of pesticides used. The mass of TWP ultimately entering the aquatic environment strongly depends on the extent of collection and treatment of road runoff, which is highly variable. For the German highways it is estimated that up to 11,000 t/a of TWP reach surface waters. Data on TWP concentrations in the environment, including surface waters are fragmentary, which is also due to the lack of suitable analytical methods for their determination. Information on TWP properties such as density and size distribution are missing; this hampers assessing the fate of TWP in the aquatic environment. Effects in the aquatic environment may stem from TWP itself or from compounds released from TWP. It is concluded that reliable knowledge on transport mechanism to surface waters, concentrations in surface waters and sediments, effects of aging, environmental half-lives of TWP as well as effects on aquatic organisms are missing. These aspects need to be addressed to allow for the assessment of risk of TWP in an aquatic environment. Graphical abstract

Description: Publication date: 1 August 2018 Source: Water Research, Volume 139 Author(s): Frederic D.L. Leusch, Peta A. Neale, Charlotte Arnal, Natalie H. Aneck-Hahn, Patrick Balaguer, Auguste Bruchet, Beate I. Escher, Mar Esperanza, Marina Grimaldi, Gaela Leroy, Marco Scheurer, Rita Schlichting, Merijn Schriks, Armelle Hebert The aquatic environment can contain numerous micropollutants and there are concerns about endocrine activity in environmental waters and the potential impacts on human and ecosystem health. In this study a complementary chemical analysis and in vitro bioassay approach was applied to evaluate endocrine activity in treated wastewater, surface water and drinking water samples from six countries (Germany, Australia, France, South Africa, the Netherlands and Spain). The bioassay test battery included assays indicative of seven endocrine pathways, while 58 different chemicals, including pesticides, pharmaceuticals and industrial compounds, were analysed by targeted chemical analysis. Endocrine activity was below the limit of quantification for most water samples, with only two of six treated wastewater samples and two of six surface water samples exhibiting estrogenic, glucocorticoid, progestagenic and/or anti-mineralocorticoid activity above the limit of quantification. Based on available effect-based trigger values (EBT) for estrogenic and glucocorticoid activity, some of the wastewater and surface water samples were found to exceed the EBT, suggesting these environmental waters may pose a potential risk to ecosystem health. In contrast, the lack of bioassay activity and low detected chemical concentrations in the drinking water samples do not suggest a risk to human endocrine health, with all samples below the relevant EBTs. Graphical abstract

Description: Publication date: 1 August 2018 Source: Water Research, Volume 139 Author(s): David B. Miklos, Christian Remy, Martin Jekel, Karl G. Linden, Jörg E. Drewes, Uwe Hübner This study provides an overview of established processes as well as recent progress in emerging technologies for advanced oxidation processes (AOPs). In addition to a discussion of major reaction mechanisms and formation of by-products, data on energy efficiency were collected in an extensive analysis of studies reported in the peer-reviewed literature enabling a critical comparison of various established and emerging AOPs based on electrical energy per order (E EO ) values. Despite strong variations within reviewed E EO values, significant differences could be observed between three groups of AOPs: (1) O 3 (often considered as AOP-like process), O 3 /H 2 O 2 , O 3 /UV, UV/H 2 O 2 , UV/persulfate, UV/chlorine, and electron beam represent median E EO values of 〈1 kWh/m 3 , while median energy consumption by (2) photo-Fenton, plasma, and electrolytic AOPs were significantly higher (E EO values in the range of 1–100 kWh/m 3 ). (3) UV-based photocatalysis, ultrasound, and microwave-based AOPs are characterized by median values of >100 kWh/m 3 and were therefore considered as not (yet) energy efficient AOPs. Specific evaluation of 147 data points for the UV/H 2 O 2 process revealed strong effects of operational conditions on reported E EO values. Besides water type and quality, a major influence was observed for process capacity (lab-vs. pilot-vs. full-scale applications) and, in case of UV-based processes, of the lamp type. However, due to the contribution of other factors, correlation of E EO values with specific water quality parameters such as UV absorbance and dissolved organic carbon were not substantial. Also, correlations between E EO and compound reactivity with OH-radicals were not significant (photolytically active compounds were not considered). Based on these findings, recommendations regarding the use of the E EO concept, including the upscaling of laboratory results, were derived. Graphical abstract

Description: Publication date: 1 August 2018 Source: Water Research, Volume 139 Author(s): Wei Wang, Yaobin Lu, Haiping Luo, Guangli Liu, Renduo Zhang, Song Jin High electrical energy is required for the electro-Fenton process to remove pharmaceuticals and personal care products (PPCPs) in wastewater. The aim of this study was to develop a novel and more cost-effective process, specifically a microbial electro-Fenton cell (MeFC), for treating PPCPs in wastewater. Acetylene black was selected as the catalyst for H 2 O 2 electrogeneration and Fe-Mn binary oxide for hydroxyl radical production. In addition to lowering energy needs, the MeFC produced a maximum power density of 112 ± 11 mW/m 2 with 1 g/L acetate as a representative substrate and 10 mg/L carbamazepine (CBZ) as a typical PPCP. Comparing with electro-Fenton process, the CBZ removal in the MeFC was 38% higher within 24 h operation (90% vs. 62%). Furthermore, the CBZ removal rate in the MeFC was 10–100 times faster than that in other biological treatment processes. Such enhanced degradation of CBZ in the MeFC was attributed to the synergistic reactions between radical oxidation of CBZ and biodegradation of degradative intermediates. The MeFC provides a promising method to remove PPCPs from wastewater coupling with efficient removal of other biodegradable organics. Graphical abstract

Description: Publication date: 1 August 2018 Source: Water Research, Volume 139 Author(s): Mashor Housh, Ziv Ohar Modern Water Distribution Systems (WDSs) are often controlled by Supervisory Control and Data Acquisition (SCADA) systems and Programmable Logic Controllers (PLCs) which manage their operation and maintain a reliable water supply. As such, and with the cyber layer becoming a central component of WDS operations, these systems are at a greater risk of being subjected to cyberattacks. This paper offers a model-based methodology based on a detailed hydraulic understanding of WDSs combined with an anomaly detection algorithm for the identification of complex cyberattacks that cannot be fully identified by hydraulically based rules alone. The results show that the proposed algorithm is capable of achieving the best-known performance when tested on the data published in the BATtle of the Attack Detection ALgorithms (BATADAL) competition ( http://www.batadal.net ).

Description: Publication date: 1 August 2018 Source: Water Research, Volume 139 Author(s): Changyin Zhu, Fengxiao Zhu, Dionysios D. Dionysiou, Dongmei Zhou, Guodong Fang, Juan Gao Alcohols such as ethanol (EtOH) and tert- butanol (TBA) are frequently used as quenching agents to identify the primary radical species in the persulfate (PS)-based oxidation processes. However, the contribution of alcohol radicals (ARs) to contaminant degradation in this process has rarely been assessed. In this study, trichloroacetic acid (TCA), phenol, and carbon tetrachloride were selected as probes to test the role of ARs in the thermally activated PS system. It was found that the degradation rates of these compounds were largely depended on their reactivities with ARs and the concentration of dissolved oxygen in the reaction system. In the PS/alcohol system, TCA was degraded efficiently under anaerobic conditions, while it was hardly degraded in the presence of oxygen. The results of electron paramagnetic resonance, reducing radical quenching studies, and the analysis of PS consumption suggested that ARs were the dominant reactive species contributing to TCA degradation in the PS/EtOH system under anaerobic conditions. Further studies indicated that ARs could significantly degrade CCl 4 through dechlorination but not phenol. CCl 4 was also degraded efficiently by ARs when oxygen in the reaction solution was completely consumed by ARs. This study highlights the important role of alcohol radicals in the degradation of contaminants during quenching studies in PS-activated processes. Graphical abstract