Monitoring the biological activity of micropollutants during advanced wastewater treatment with ozonation and activated carbon filtration

Long-term impact of Hurricane Maria on point-of-use drinking water quality in Puerto Rico and associated potential adverse health effects

Drinking water security in Puerto Rico (PR) is increasingly challenged by both regulated and emerging anthropogenic contaminants, which was exacerbated by the Hurricane Maria (HM) due to impaired regional water cycle and damaged water infrastructure. Leveraging the NIEHS PROTECT (Puerto Rico Testsite for Exploring Contamination Threats) cohort, this study assessed the long-term tap water (TW) quality changes from March 2018 to November 2018 after HM in PR, by innovatively integrating two different effect-based quantitative toxicity assays with a targeted analysis of 200 organic and 22 inorganic pollutants. Post-hurricane PR TW quality showed recovery after >6-month period as indicated by the decreased number of contaminants showing elevated average concentrations relative to pre-hurricane samples, with significant difference of both chemical and toxicity levels between northern and southern PR. Molecular toxicity profiling and correlation revealed that the HM-accelerated releases of certain pesticides and PPCPs could exert increased cellular oxidative and/or AhR (aryl hydrocarbon receptor)-mediated activities that may persist for more than six months after HM. Maximum cumulative ratio and adverse outcome pathway (AOP) assessment identified the top ranked detected TW contaminants (Cu, Sr, V, perfluorooctanoic acid) that potentially associated with different adverse health effects such as inflammation, impaired reproductive systems, cancers/tumors, and/or organ toxicity. These insights can be incorporated into the regulatory framework for post-disaster risk assessment, guiding water quality control and management for public health protection.

Mammalian Cell Genotoxicity of Potable Reuse and Conventional Drinking Waters

Potable reuse water is increasingly part of the water supply portfolio for municipalities facing water shortages, and toxicity assays can be useful for evaluating potable reuse water quality. We examined the Chinese hamster ovary cell acute direct genotoxicity of potable reuse waters contributed by disinfection byproducts (DBPs) and anthropogenic contaminants and used the local conventional drinking waters as benchmarks for evaluating potable reuse water quality. Our results showed that treatment trains based on reverse osmosis (RO) were more effective than RO-free treatment trains for reducing the genotoxicity of influent wastewaters. RO-treated reuse waters were less genotoxic than the local tap water derived from surface water, whereas reuse waters not treated by RO were similarly genotoxic as the local drinking waters when frequent replacement of granular activated carbon limited contaminant breakthrough. The genotoxicity contributed by nonvolatile, uncharacterized DBPs and anthropogenic contaminants accounted for ≥73% of the total genotoxicity. The (semi)volatile DBPs of current research interest contributed 2-27% toward the total genotoxicity, with unregulated DBPs being more important genotoxicity drivers than regulated DBPs. Our results underscore the need to look beyond known, (semi)volatile DBPs and the importance of determining whole water toxicity when assessing the quality of disinfected waters.

In vitro bioassays to monitor complex chemical mixtures at a carbon-based indirect potable reuse plant

Potable water reuse technologies are used to treat wastewater to drinking water quality to help sustain a community's water resources. California has long led the adoption of potable water reuse technologies in the United States and more states are exploring these technologies as water resources decline. Reuse technologies also need to achieve adequate reductions in microbial and chemical contaminant risks to meet public health goals and secure public acceptance. In vitro bioassays are a useful tool for screening if reuse treatment processes adequately reduce toxicity associated with a range of chemical classes that are contaminants of concern. In this study, we used an aryl hydrocarbon receptor (AhR) and an estrogen receptor luciferase bioassay to detect the presence of dioxin-like and estrogenic compounds across a 3800 m³/d carbon-based indirect potable reuse plant that uses carbon-based treatment (SWIFT-RC). Our results demonstrate significant removal of dioxin-like compounds across the SWIFT-RC treatment train. Estrogenicity declined across the treatment train for some months but was extremely variable and low with many samples falling below the method quantification level; consequently, we were not able to reliably determine estrogenicity trends for SWIFT-RC. Comparing the bioanalytical equivalent concentrations detected in the SWIFT-RC water with established monitoring trigger levels from the state of California suggests that SWIFT-RC produced water that met the bioassay guidelines. The log total organic carbon concentration and AhR assay equivalent concentrations are weakly correlated when data across all SWIFT-RC processes are included. Overall, this research demonstrates the performance of in vitro bioassays at a demonstration-scale carbon-based IPR system and highlights both the potential utility and challenges associated with these methods for assessing system performance.

Application of Effect-Based Methods to Water Quality Monitoring: Answering Frequently Asked Questions by Water Quality Managers, Regulators, and Policy Makers

Effect-based methods (EBM) have great potential for water quality monitoring as they can detect the mixture effects of all active known and unknown chemicals in a sample, which cannot be addressed by chemical analysis alone. To date, EBM have primarily been applied in a research context, with a lower level of uptake by the water sector and regulators. This is partly due to concerns regarding the reliability and interpretation of EBM. Using evidence from the peer-reviewed literature, this work aims to answer frequently asked questions about EBM. The questions were identified through consultation with the water industry and regulators and cover topics related to the basis for using EBM, practical considerations regarding reliability, sampling for EBM and quality control, and what to do with the information provided by EBM. The information provided in this work aims to give confidence to regulators and the water sector to stimulate the application of EBM for water quality monitoring.

New insights into the transformation of effluent organic matter during Fe(II)-assisted advanced oxidation processes: Parallel factor analysis coupled with self-organizing maps

The negative effects of effluent organic matter (EfOM) on receiving aquatic environments and advanced treatment facilities pose significant concerns. However, the effective removal of EfOM is challenging due to its chemically complex nature and its refractory characteristics. In this study, two Fe(II)-assisted oxidation processes including UV/Fe(II)/H₂O₂ and UV/Fe(II)/persulfate (UV/Fe(II)/PS) were investigated to promote EfOM reduction. Fe(II) was essential for promoting EfOM degradation. The mineralization rate of EfOM increased from 7 to 29% with 2 mM Fe(II) addition in the UV/H₂O₂ process and to 23% with 0.8 mM Fe(II) addition in the UV/PS process. A preliminary experiment was conducted to obtain the optimal molar ratio of oxidant to Fe(II) for practical applications based on different indicators. The form of Fe(III) prevalent at different pH values strongly affected Fe(II)/Fe(III) cycling, thus determining the progress of EfOM degradation. A machine learning approach consisting of parallel factor analysis coupled with self-organizing maps (PARAFAC-SOM) was employed with fluorescence spectra to visualize the degradation behavior of EfOM in the different reaction systems. Four components (i.e., two humic-like substances, one fulvic acid, and one tryptophan-like substance) were eventually identified, and their reductions reached more than 62% during the Fe(II)-assisted oxidation processes. The degradation orders for each component in the different oxidation processes were initially evaluated by SOM analysis with F_max percentage data. The degradation behavior of EfOM in the UV/Fe(II)/H₂O₂ and UV/Fe(II)/PS systems exhibited different trends based on the best matching unit map and component planes. The humic-like component was more refractory than the other three components in both oxidation processes. The microbial humic-like and high-molecular-weight fulvic acid substances showed higher reactivity with SO·₄^- than with ·OH, while the tryptophan-like substance was more reactive in the UV/Fe(II)/H₂O₂ system than in the UV/Fe(II)/PS system. The outcomes of this study provide new insights into the degradation behavior of EfOM, promoting the development of advanced wastewater treatments.

Evaluation of a full-scale wastewater treatment plant with ozonation and different post-treatments using a broad range of in vitro and in vivo bioassays

Micropollutants present in the effluent of wastewater treatment plants (WWTPs) after biological treatment are largely eliminated by effective advanced technologies such as ozonation. Discharge of contaminants into freshwater ecosystems can thus be minimized, while simultaneously protecting drinking water resources. However, ozonation can lead to reactive and potentially toxic transformation products. To remove these, the Swiss Federal Office for the Environment recommends additional "post-treatment" of ozonated WWTP effluent using sand filtration, but other treatments may be similarly effective. In this study, 48 h composite wastewater samples were collected before and after full-scale ozonation, and after post-treatments (full-scale sand filtration, pilot-scale fresh and pre-loaded granular activated carbon, and fixed and moving beds). Ecotoxicological tests were performed to quantify the changes in water quality following different treatment steps. These included standard in vitro bioassays for the detection of endocrine, genotoxic and mutagenic effects, as well as toxicity to green algae and bacteria, and flow-through in vivo bioassays using oligochaetes and early life stages of rainbow trout. Results show that ozonation reduced a number of ecotoxicological effects of biologically treated wastewater by 66 - 93%: It improved growth and photosynthesis of green algae, decreased toxicity to luminescent bacteria, reduced concentrations of hormonally active contaminants and significantly changed expression of biomarker genes in rainbow trout liver. Bioassay results showed that ozonation did not produce problematic levels of reaction products overall. Small increases in toxicity observed in a few samples were reduced or eliminated by post-treatments. However, only relatively fresh granular activated carbon (analyzed at 13,000 - 20,000 bed volumes) significantly reduced effects additionally (by up to 66%) compared to ozonation alone. Inhibition of algal photosynthesis, rainbow trout liver histopathology and biomarker gene expression proved to be sufficiently sensitive endpoints to detect the change in water quality achieved by post-treatment.

Fourth generation biofuel from genetically modified algal biomass: Challenges and future directions

Genetic engineering applications in the field of biofuel are rapidly expanding due to their potential to boost biomass productivity while lowering its cost and enhancing its quality. Recently, fourth-generation biofuel (FGB), which is biofuel obtained from genetically modified (GM) algae biomass, has gained considerable attention from academic and industrial communities. However, replacing fossil resources with FGB is still beset with many challenges. Most notably, technical aspects of genetic modification operations need to be more fully articulated and elaborated. However, relatively little attention has been paid to GM algal biomass. There is a limited number of reviews on the progress and challenges faced in the algal genetics of FGB. Therefore, the present review aims to fill this gap in the literature by recapitulating the findings of recent studies and achievements on safe and efficient genetic manipulation in the production of FGB. Then, the essential issues and parameters related to genome editing in algal strains are highlighted. Finally, the main challenges to FGB pertaining to the diffusion risk and regulatory frameworks are addressed. This review concluded that the technical and biosafety aspects of FGB, as well as the complexity and diversity of the related regulations, legitimacy concerns, and health and environmental risks, are among the most important challenges that require a strong commitment at the national/international levels to reach a global consensus.

Removal efficiencies and risk assessment of endocrine-disrupting chemicals at two wastewater treatment plants in South China

Endocrine-disrupting chemicals (EDCs) in the effluent from wastewater treatment plants (WWTPs) are an important pollutant sources of the aquatic system. In this study, the removal efficiencies of eight typical EDCs at two domestic WWTPs in Dongguan City, China, are reported based on instrumental analysis and bioassay results. Bioactivities, including steroidogenesis-disrupting effects, estrogen receptor (ER)-binding activity, and aryl hydrocarbon receptor (AhR)-binding activity were evaluated using the H295R, MVLN, and H4IIE cell bioassays, respectively. The potential environmental risks of these residual EDCs were also evaluated. The results of instrumental analysis showed that nonylphenol was the major chemical type present among the eight tested EDCs. Meanwhile, concentrations of estrogen compounds including estrone, 17β-estradiol (E2), estriol, 17α-ethinyl estradiol, and diethylstilbestrol were relatively low. The removal rates of all eight EDCs were relatively high. Although the chemical analysis indicated high removal efficiency, the bioassay results showed that steroidogenesis-disrupting effects as well as ER-binding and AhR-binding activities remained, with E2-equivalent values of effluent samples ranging from 0.16 to 0.9 ng·L^-1, and 2,3,7,8-tetrachlorodibenzo-p-dioxin-equivalent values ranging from 0.61 to 4.09 ng L^-1. Principal component analysis combined with regression analysis suggests that the chemicals analyzed in this study were partly responsible for these ER and AhR activities. Ecological risk assessment of the residual EDCs showed that estrone was the most hazardous chemical among the eight EDCs tested, with a risk quotient of 1.44-5.50. Overall, this study suggests that, despite high apparent removal efficiencies of typical EDCs, their bioactivities and potential ecological risks cannot be ignored.

Removal of Micropollutants by Ozone-Based Processes

Micropollutants and emerging substances pose a serious problem to environmental sustainability and remediation, due to their widespread use and applications in everyday life. This group of chemicals is diverse but with common toxic and harmful properties. Their concentration in the environment is often very low; however, due to their recalcitrant nature, they are persistent in air, water, and soil. From an engineering point of view, the challenge is not straightforward. It is difficult to remove these contaminants from complex mixtures of substances by conventional methods used in wastewater and drinking water treatment. Ozonation and ozone-based AOPs are accepted processes of degradation of resistant substances or at least enhancement of their biodegradability. The aim of this review paper is to present research trends aimed at solving problems in the research and application of ozone-based processes in the removal of micropollutants from wastewater, thus preventing leakage of harmful substances into surface water, soil, and groundwater and facilitating the reuse of wastewater. Priority substances, micropollutants and emerging pollutants, as well as processes and technologies for their transformation and elimination, are briefly specified. Results obtained by the authors in solving research projects that were aimed at eliminating selected micropollutants by ozonation and ozone-based AOPs are also presented. This review focuses on selected alkylphenols, petroleum substances, and organochlorine pesticides.

Effect-based evaluation of ozone treatment for removal of micropollutants and their transformation products in waste water

The aim of this interdisciplinary research project in North Rhine-Westphalia (NRW), Germany, entitled "Elimination of pharmaceuticals and organic micropollutants from waste water" involved the conception of cost-effective and innovative waste-water cleaning methods. In this project in vitro assays, in vivo assays and chemical analyses were performed on three municipal waste-water treatment plants (WWTP). This publication focuses on the study of the in vitro bioassays. Cytotoxic, estrogenic, genotoxic and mutagenic effects of the original as well as enriched water samples were monitored before and after wastewater treatment steps using MTT and PAN I, ER Calux and A-YES, micronucleus and Comet assays as well as AMES test. In most cases, the measured effects were reduced after ozonation, but in general, the biological response depended upon the water composition of the WWTP, in particular on the formed by-products and concentration of micropollutants. In order to be able to assess the genotoxic and/or mutagenic potential of waste-water samples using bioassays like Ames test, Comet assay or micronucleus test an enrichment of the water sample via solid-phase extraction is recommended. This is in agreement with previous studies such as the "ToxBox"-Project of the Environmental Agency in Germany.

Genotoxic activities of wastewater after ozonation and activated carbon filtration: Different effects in liver-derived cells and bacterial indicators

Aim of this study was to investigate the impact of advanced wastewater treatment techniques (combining ozonation with activated carbon filtration) on acute and genotoxic activities of tertiary treated wastewater. Concentrated samples were tested in Salmonella/microsome assays. Furthermore, induction of DNA damage was measured in liver-derived cells (human hepatoma and primary rat hepatocytes) in single cell gel electrophoresis experiments, which are based on the measurement of DNA migration in an electric field. These cell types possess phase I and phase II enzymes, which catalyze the activation/detoxification of mutagens. Acute toxicity was determined with the trypan blue exclusion technique. We found no evidence for mutagenic effects of non-ozonated samples in several bacterial tester strains (TA98, TA100, YG7108, YG7104, YG7112 and YG7113) but clear induction of His⁺ mutants after O₃ treatment in two strains with defective genes encoding for DNA repair, which are highly sensitive towards alkylating agents (YG7108 and YG7104). These effects were reduced after activated carbon filtration. Furthermore, we detected a slight increase of mutagenic activity in strain YG1024 with increased acetyltransferase activity, which is sensitive towards aromatic amines and nitro compounds in untreated water, which was not reduced by O₃ treatment. A completely different pattern of mutagenic activity was seen in liver-derived cells; non ozonated samples caused in both cell types pronounced DNA damage, which was reduced (by ca. 25%) after ozonation. Activated carbon treatment did not cause a substantial further reduction of DNA damage. Additional experiments with liver homogenate indicate that the compounds which cause the effects in the human cells are promutagens which require enzymatic activation. None of the waters caused acute toxicity in the liver-derived cells and in the bacterial indicators. Assuming that hepatic mammalian cells reflect the genotoxic properties of the waters in vertebrates (including humans) more adequately as genetically modified bacterial indicators, we conclude that ozonation has beneficial effects in regard to the reduction of genotoxic properties of treated wastewaters.

Surrogates for the removal by ozonation of the cytotoxicity and DNA double-strand break effects of wastewater on mammalian cells

Effluents from wastewater treatment plants (WWTPs) may contain various pollutants with potential toxic effects. Ozonation is widely applied to purify wastewater, which may influence the toxicity and water quality indices simultaneously. The main goal of this study was to reveal influence of ozonation on toxicity of WWTP effluents and to find the surrogates for toxicity changes. Cytotoxicity and DNA double-strand break (DSB) effect of WWTP effluents were measured based on Chinese hamster ovary (CHO) cells. Changes of water quality parameters and molecular weight distribution of WWTP effluents were also measured. The organic extracts in WWTP effluents were shown to decrease the cell viability. Besides, an increased level of DNA DSBs was found in cells when exposed to the organic extracts. Ozonation significantly eliminated cytotoxicity and DNA DSB-based genotoxicity of WWTP effluents, with removal rates of 53-66% and 51-76% for cytotoxicity and genotoxicity, respectively, with 10 mg/L ozone dose. Although the DOC contents in WWTP effluents were hardly removed by ozonation, the chromophores and fluorophores were significantly eliminated. Organic matter in WWTP effluents mainly consists of fractions with molecular weight (MW) < 500 Da. Ozonation generally decreased the fluorescence intensity and UV₂₅₄ values of all the MW fractions, but increased the DOC contents of the 100-500 Da fraction. During ozonation, the removal rates of UV₂₅₄ and SUVA₂₅₄ were significantly correlated to the removal rates of both cytotoxicity and genotoxicity. UV₂₅₄ might be an ideal surrogate for cytotoxicity and genotoxicity reduction during wastewater ozonation.

Controlling micropollutants in tertiary municipal wastewater by O3/H2O2, granular biofiltration and UV254/H2O2 for potable reuse applications

A comprehensive pilot study was carried out to experimentally assess the potential of newly developed treatment trains integrating two-stage AOPs and biofiltration to reach potable reuse water quality standards from municipal wastewater. The processes consisted of a two-stage AOPs with (carbon or limestone) biofiltration, the first AOP (O₃/H₂O₂) serving as pre-treatment to biofiltration and the second AOP (UV₂₅₄/H₂O₂) serving as post-biofiltration finishing step to ensure advanced disinfection. A comprehensive monitoring campaign was put in place resulting from the combination of targeted, non-targeted and suspect screening measurements. It was found that 13 organic micropollutants were detected from a list of 219 suspects although at ng/L level only. For the treatment conditions piloted in this study (O₃ = 13 ± 0.5 mg/L, H₂O₂ = 11 ± 0.4 mg/L for the O₃/H₂O₂ process, and UV = 410 ± 63.5 mJ/cm², H₂O₂ = 5 mg/l for the UV₂₅₄/H₂O₂ process), it was possible to estimate the overall removal efficacy for each unit process, which was found to follow this order: RO (99%)  > BAC (87%) > O₃-H₂O₂ (78%)  > BAL (67%)  > UV/H₂O₂ (43%)  > AOP contact chamber (19%)  > UF(0%), with the treatment train integrating two AOPs and granular biofiltration with activated carbon (O₃/H₂O₂ + BAC + UV₂₅₄/H₂O₂) showing superior performance with a 99% abatement in total micropollutants. No ecotoxicologically-positive response was generally observed for any of the effluent samples from the tested trains, even when pre-concentration factors up to 100-1000 times were employed to increase the sensitivity of the bioassay methods.

Effect-Directed Analysis of Progestogens and Glucocorticoids at Trace Concentrations in River Water

Effect-based monitoring is increasingly applied to detect and-in conjunction with chemical analysis-to identify endocrine-disrupting compounds (EDCs) in the environment. Although this approach of effect-directed analysis has been successfully demonstrated for estrogenicity and androgenicity, data on progestogens and glucocorticoids driving endocrine disruption are quite limited. We investigated progestogenic and glucocorticoid activities in Danube River water receiving untreated wastewater from Novi Sad, Serbia. After a 2-step fractionation, all fractions were tested with reporter gene bioassays for agonistic and antagonistic hormonal responses at progestogenic and glucocorticoid hormone receptors as well as with target and nontarget analytical screening of active fractions by liquid chromatography-high-resolution mass spectrometry. Due to masking by cytotoxic mixture components, the effects could not be detected in the raw water extract but were unraveled only after fractionation. Target chemical screening of the fraction that was active in the progesterone receptor (PR) assay revealed that progesterone and megestrol acetate were predominant drivers of PR-mediated activity along with medroxyprogesterone, dihydrotestosterone, androsterone, and epiandrosterone. Hydrocortisone was detected at sub-ng/L concentration in the active fraction in the glucocorticoid receptor (GR) assay but could not explain a significant fraction of the observed GR activity. The present study indicates that effect-based monitoring is a powerful tool to detect EDCs in the aquatic environment but that fractionation may be required to avoid masking effects of mixture components. Future effect-directed analysis studies are required to better understand the occurrence of EDCs and masking compounds in different lipophilicity windows, to finally reduce fractionation requirements for monitoring to a smart clean-up. Environ Toxicol Chem 2019;39:189-199. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

The treatability of trace organic pollutants in WWTP effluent and associated biotoxicity reduction by advanced treatment processes for effluent quality improvement

As increasing attention is paid to surface water protection, there has been demand for improvements of domestic wastewater treatment plant (WWTP) effluent. This has led to the application of many different advanced treatment processes (ATPs). In this study, the treatability of trace organic pollutants in secondary effluent (SE) and associated biotoxicity reduction by four types of ATPs, including coagulation, granular activated carbon (GAC) adsorption, ultraviolet (UV) photolysis and photocatalysis, and ozonation, were investigated at the bench-scale. The ATPs showed different removal capacity for the 48 chemicals, which were classified into seven categories. EDCs, herbicides, bactericides and pharmaceuticals were readily degraded, and insecticides, flame retardants, and UV filters were relatively resistant to removal. During these processes, the efficiency of the ATPs in reducing four biological effects were investigated. Of the four biological effects, the estrogenic activity from SE was not detected using the yeast estrogen screen. In contrast with genotoxicity and photosynthesis inhibition, bacterial cytotoxicity posed by SE was the most difficult biological effect to reduce with these ATPs. GAC adsorption and ozonation were the most robust treatment processes for reducing the three detected biotoxicities. UV photolysis and photocatalysis showed comparable efficiencies for the reduction of genotoxicity and photosynthesis inhibition. However, coagulation only performed well in genotoxicity reduction. The effect-based trigger values for the four bioassays, that were derived from the existing environmental quality standards and from HC5 (hazardous concentration for 5% of aquatic organisms), were all used to select and optimize these ATPs for ecological safety. Conducting ATPs in more appropriate ways could eliminate the negative effects of WWTP effluent on receiving water bodies.

Systematic Review of Toxicity Removal by Advanced Wastewater Treatment Technologies via Ozonation and Activated Carbon

Upgrading wastewater treatment plants (WWTPs) with advanced technologies is one key strategy to reduce micropollutant emissions. Given the complex chemical composition of wastewater, toxicity removal is an integral parameter to assess the performance of WWTPs. Thus, the goal of this systematic review is to evaluate how effectively ozonation and activated carbon remove in vitro and in vivo toxicity. Out of 2464 publications, we extracted 46 relevant studies conducted at 22 pilot or full-scale WWTPs. We performed a quantitative and qualitative evaluation of in vitro (100 assays) and in vivo data (20 species), respectively. Data is more abundant on ozonation (573 data points) than on an activated carbon treatment (162 data points), and certain in vitro end points (especially estrogenicity) and in vivo models (e.g., daphnids) dominate. The literature shows that while a conventional treatment effectively reduces toxicity, residual effects in the effluents may represent a risk to the receiving ecosystem on the basis of effect-based trigger values. In general, an upgrade to ozonation or activated carbon treatment will significantly increase toxicity removal with similar performance. Nevertheless, ozonation generates toxic transformation products that can be removed by a post-treatment. By assessing the growing body of effect-based studies, we identify sensitive and underrepresented end points and species and provide guidance for future research.

In vitro bioanalytical evaluation of removal efficiency for bioactive chemicals in Swedish wastewater treatment plants

Chemical contamination of wastewater is a problem of great environmental concern, as it poses a hazard to both the ecosystem and to human health. In this study, we have performed a bioanalytical evaluation of the presence and removal efficiency for bioactive chemicals in wastewater treatment plants (WWTPs), using in vitro assays for toxicity endpoints of high relevance for human health. Water samples were collected at the inlet and outlet of five Swedish WWTPs, all adopting a treatment technology including pretreatment, primary treatment (sedimenation), seconday treatment (biological processes), post-sedimentation, and sludge handling. The water samples were analyzed for cytotoxicity, estrogenicity, androgenicity, aryl hydrocarbon receptor (AhR) activity, oxidative stress response (Nrf2) and the ability to activate NFĸB (nuclear factor kappa-light-chain-enhancer of activated B cells) signaling. We observed clear androgenic and estrogenic activities in all inlet samples. Androgenic and estrogenic activities were also observed in all outlet samples, but the activities were lower than the respective inlet sample. AhR activity was observed in all samples, with higher activities in the inlet samples compared to the outlet samples. The removal efficiency was found to be high for androgenic (>99% for two plants and 50–60% for two plants) and estrogenic (>90% for most plants) compounds, while the removal efficiency for AhR-inducing compounds was 50–60% for most plants and 16% for one plant.

Investigation on degradation behavior of dissolved effluent organic matter, organic micro-pollutants and bio-toxicity reduction from secondary effluent treated by ozonation

The environmental risk of secondary effluent has caused increasing attention in recent years, the negative effect of dissolved effluent organic matters (dEfOM) and organic micro-pollutants (OMPs) was a hot research point. In this research, the degradation behavior of dEfOM and fourteen OMPs in the ozonation was revealed using spectroscopic and chromatographic tools. Ozonation was effective for reducing UV₂₅₄, but had limited effect in dissolved organic carbon reduction. The dEfOM with shorter absorption wavelength was preferentially removed in the ozonation (230 nm  >  240 nm > 254 nm) and high molecular weight humics was largely reduced by the ozonation. Soluble microbial by-products were more reactive with ozone than humic acid as reflected by the fluorescence. Degradation behavior of the OMPs was identified based on their elimination kinetics and molecular structures and a simplified classification method was proposed. The group I OMPs (logk_O3>5) showed high removal efficiency with 1 mg/L of ozone, while the removal of group II OMPs (1< logk_O3<5) was largely dependent on the ozone dose. The CC bond, deprotonated amidogen, phenolic, aniline and anisole groups in these OMPs structures were the main reaction sites with ozone. The group III OMPs without active groups in the molecules showed slight removal in the ozonation. Moreover, genotoxicity and estrogenic activity were simultaneously analyzed for further evaluation on the risk of the effluent. The genotoxicity and estrogenic activity of the secondary effluent were 73.46 μg 4-NQO/L and 519.86 ng E2/L, respectively and an ozone dose of 10 mg/L could reduce the bio-toxicity to the detection limit.

Risk-based approach in the revised European Union drinking water legislation: Opportunities for bioanalytical tools

A plethora of in vitro bioassays are developed in the context of chemical risk assessment and clinical diagnostics to test effects on different biological processes. Such assays can also be implemented in effect-based monitoring (EBM) of (drinking) water quality alongside chemical analyses. Effects-based monitoring can provide insight into risks for the environment and human health associated with exposure to (unknown) complex, low-level mixtures of micropollutants, which fits in the risk-based approach that was recently introduced in the European Drinking Water Directive. Some challenges remain, in particular those related to selection and interpretation of bioassays. For water quality assessment, carcinogenesis, adverse effects on reproduction and development, effects on xenobiotic metabolism, modulation of hormone systems, DNA reactivity, and adaptive stress responses are considered the most relevant toxicological endpoints. An evaluation procedure of the applicability and performance of in vitro bioassays for water quality monitoring, based on existing information, has been developed, which can be expanded with guidelines for experimental evaluations. In addition, a methodology for the interpretation of in vitro monitoring data is required, because the sensitivity of specific in vitro bioassays in combination with sample concentration may lead to responses of chemicals (far) below exposure concentrations that are relevant for human health effects. Different approaches are proposed to derive effect-based trigger values (EBTs), including EBTs based on (1) relative ecotoxicity potency, (2) health-based threshold values for chronic exposure in humans and kinetics of reference chemicals, and (3) read-across from (drinking) water guideline values. Effects-based trigger values need to be chosen carefully in order to be sufficiently but not overly conservative to indicate potential health effects. Consensus on the crucial steps in the selection and interpretation of in vitro bioassay data will facilitate implementation and legal embedding in the context of water quality monitoring of such assays in EBM strategies. Integr Environ Assess Manag 2019;15:126-134. © 2018 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Evaluation of attenuation of pharmaceuticals, toxic potency, and antibiotic resistance genes in constructed wetlands treating wastewater effluents

The performance of constructed wetlands (CWs) in the removal of pharmaceutically active compounds (PhACs) is generally evaluated on the basis of chemical analysis. In this work, we used a combination of chemical, toxicological, and molecular analyses to assess the attenuation of PhACs, toxic potency and antibiotic resistance genes (ARGs) in a field study of three CWs serving as tertiary treatment of wastewater treatment plants. First, 17 PhACs were analysed chemically, of which 14 were detected and seven at concentrations >0.1μg/l. Even though some of the individual PhACs were moderately or highly removed in the CWs investigated, median removal of overall PhACs was approximately 50% in the vertical subsurface flow CW (VSF-CW) with a lower hydraulic loading rate while the removal in the other two free water surface flow CWs (SF-CWs) was negligible. Second, toxic potency of wastewater extracts was assessed in a range of bioassays. Estrogenicity was overall attenuated in CWs, while the neurotoxic potency of wastewater extracts did not decrease after passage through the two CWs investigated. Third, the VSF-CW and one of the SF-CW showed a positive removal of an integrase gene and three ARGs tested. The increased concentrations of ARGs in the other SF-CW, as well as the increase of total bacteria in all CWs, may relate to regrowth of resistance-carrying bacteria. Finally, multivariate analysis shows that most PhACs are positively correlated to the observed toxic potency. Additionally, low removal of organics and nutrients seems to parallel with low removal of PhACs. ARGs positively correlated with organics, nutrients and some PhACs, and the integrase gene but not to the respective antibiotics. The insufficient removal of PhACs, toxic potency, and ARGs indicates the need of an optimal design of CWs as tertiary treatment facilities.

Effect-based trigger values for in vitro and in vivo bioassays performed on surface water extracts supporting the environmental quality standards (EQS) of the European Water Framework Directive

Effect-based methods including cell-based bioassays, reporter gene assays and whole-organism assays have been applied for decades in water quality monitoring and testing of enriched solid-phase extracts. There is no common EU-wide agreement on what level of bioassay response in water extracts is acceptable. At present, bioassay results are only benchmarked against each other but not against a consented measure of chemical water quality. The EU environmental quality standards (EQS) differentiate between acceptable and unacceptable surface water concentrations for individual chemicals but cannot capture the thousands of chemicals in water and their biological action as mixtures. We developed a method that reads across from existing EQS and includes additional mixture considerations with the goal that the derived effect-based trigger values (EBT) indicate acceptable risk for complex mixtures as they occur in surface water. Advantages and limitations of various approaches to read across from EQS are discussed and distilled to an algorithm that translates EQS into their corresponding bioanalytical equivalent concentrations (BEQ). The proposed EBT derivation method was applied to 48 in vitro bioassays with 32 of them having sufficient information to yield preliminary EBTs. To assess the practicability and robustness of the proposed approach, we compared the tentative EBTs with observed environmental effects. The proposed method only gives guidance on how to derive EBTs but does not propose final EBTs for implementation. The EBTs for some bioassays such as those for estrogenicity are already mature and could be implemented into regulation in the near future, while for others it will still take a few iterations until we can be confident of the power of the proposed EBTs to differentiate good from poor water quality with respect to chemical contamination.

Removal of ozonation products of pharmaceuticals in laboratory Moving Bed Biofilm Reactors (MBBRs)

The major pathway of pharmaceuticals from urban applications to urban surface waters is via wastewater treatment plants. Ozonation is able to remove pharmaceuticals from wastewater effluents. However, during that reaction, ozonation products are formed. Some ozonation products were found to be persistent and have adverse effect on the environment. Moving bed bio reactors (MBBRs) were tested for the removal of the ozonation products of macrolide antibiotics and diclofenac at two different concentration levels 1 μg/L and 10 μg/L in laboratory reactors. It was found that the MBBRs are capable of degrading these compounds without back-transformation into the parent compounds. However, reaction rate constants and the degradation kinetics varied for different compounds and different concentrations. Depending on compound and conditions, the degradation reaction kinetics was found to follow either i) zero order ii) first order or iii) lag phase succeeded by first order. The study has proven that MBBRs have the potential to be efficient in polishing post ozonation treatment.

Toxicity bioassays with concentrated cell culture media-a methodology to overcome the chemical loss by conventional preparation of water samples

The use of in vitro bioassays for studies of toxic activity in environmental water samples is a rapidly expanding field of research. Cell-based bioassays can assess the total toxicity exerted by a water sample, regardless whether the toxicity is caused by a known or unknown agent or by a complex mixture of different agents. When using bioassays for environmental water samples, it is often necessary to concentrate the water samples before applying the sample. Commonly, water samples are concentrated 10-50 times. However, there is always a risk of losing compounds in the sample in such sample preparation. We have developed an alternative experimental design by preparing a concentrated cell culture medium which was then diluted in the environmental water sample to compose the final cell culture media for the in vitro assays. Water samples from five Swedish waste water treatment plants were analyzed for oxidative stress response, estrogen receptor (ER), and aryl hydrocarbon receptor (AhR) activity using this experimental design. We were able to detect responses equivalent to 8.8-11.3 ng/L TCCD for AhR activity and 0.4-0.9 ng/L 17β-estradiol for ER activity. We were unable to detect oxidative stress response in any of the studied water samples. In conclusion, we have developed an experimental design allowing us to examine environmental water samples in toxicity in vitro assays at a concentration factor close to 1, without the risk of losing known or unknown compounds during an extraction procedure.

Evaluation of wastewater treatment by ozonation for reducing the toxicity of contaminants of emerging concern to rainbow trout (Oncorhynchus mykiss)

Although conventional wastewater treatment technologies are effective at removing many contaminants of emerging concern (CECs) from municipal wastewater, some contaminants are not removed efficiently. Ozonation may be a treatment option for reducing the concentrations of recalcitrant CECs in wastewater, but this process may generate toxic transformation products. In the present study, we conducted semibatch experiments to ozonate municipal wastewater effluent spiked with 5 commonly detected CECs. The purpose of the present study was to evaluate whether ozonation increased or decreased biological responses indicative of sublethal toxicity in juvenile rainbow trout (Oncorhynchus mykiss) injected intraperitoneally (i.p.) with extracts prepared from ozonated and nonozonated wastewater effluent. Blood, liver, and brain tissues were collected from the fish at 72 h post injection for analysis of a battery of biomarkers. In fish i.p. injected with the extracts from nonozonated wastewater effluent, significant induction of plasma vitellogenin (VTG) was observed, but ozonation of the municipal wastewater effluent spiked with CECs significantly reduced this estrogenic response. However, in fish injected with extracts from spiked municipal wastewater effluent after ozonation, the balance of hepatic glutathione in its oxidized (glutathione disulfide [GSSG]) form was altered, indicating oxidative stress. Levels of the neurotransmitter serotonin were significantly elevated in brain tissue from trout injected with the extracts from ozonated spiked municipal wastewater effluent, a biological response that has not been previously reported in fish. Other in vivo biomarkers showed no significant changes across treatments. These results indicate that ozonation reduces the estrogenicity of wastewater, but may increase other sublethal responses. The increase in biomarker responses after ozonation may be because of the formation of biologically active products of transformation of CECs, but further work is needed to confirm this conclusion. Environ Toxicol Chem 2018;37:274-284. © 2017 SETAC.

Effect-based assessment of toxicity removal during wastewater treatment

Wastewaters contain complex mixtures of chemicals, which can cause adverse toxic effects in the receiving environment. In the present study, the toxicity removal during wastewater treatment at seven municipal wastewater treatment plants (WWTPs) was investigated using an effect-based approach. A battery of eight bioassays was applied comprising of cytotoxicity, genotoxicity, endocrine disruption and fish embryo toxicity assays. Human cell-based CALUX assays, transgenic larval models and the fish embryo toxicity test were particularly sensitive to WWTP effluents. The results indicate that most effects were significantly reduced or completely removed during wastewater treatment (76-100%), while embryo toxicity, estrogenic activity and thyroid disruption were still detectable in the effluents suggesting that some harmful substances remain after treatment. The responsiveness of the bioassays was compared and the human cell-based CALUX assays showed highest responsiveness in the samples. Additionally, the fish embryo toxicity test and the transgenic larval models for endocrine disrupting effects showed high responsiveness at low sample concentrations in nearly all of the effluent samples. The results showed a similar effect pattern among all WWTPs investigated, indicating that the wastewater composition could be rather similar at different locations. There were no considerable differences in the toxicity removal efficiencies of the treatment plants and no correlation was observed with WWTP characteristics, such as process configuration or sludge age. This study demonstrated that a biotest battery comprising of multiple endpoints can serve as a powerful tool when assessing water quality or water treatment efficiency in a holistic manner. Rather than analyzing the concentrations of a few selected chemicals, bioassays can be used to complement traditional methods of monitoring in the future by assessing sum-parameter based effects, such as mixture effects, and tackling chemicals that are present at concentrations below chemical analytical detection limits.

Comprehensive evaluation of three sets of advanced wastewater treatment trains for treating secondary effluent: Organic micro-pollutants and bio-toxicity

The environmental presence of organic micro-pollutants (OMPs) has posed increasing risks on aquatic organism and human health. The performance of three commonly used advanced wastewater treatment trains, coagulation-sand filter, coagulation-biological aerated filter (BAF) and ozonation-biological activated carbon (BAC), in removing fifteen residual contaminants and bio-toxicity of the effluent from a local municipal wastewater treatment plant (WWTP) were investigated. Relatively high level of OMPs (0.69-14.71 μg/L), genotoxicity (22.64 μg 4-NQO/L) and estrogenic activity (1.4 μg E2/L) were observed from the secondary effluent (SE). Limited OMPs and bio-toxicity reduction was achieved during coagulation with 20 mg/L of polymeric aluminium and sand filter. Ozonation exhibited high advantage in OMPs, genotoxicity and estrogenic activity reduction. More than 80% of removal was achieved for most OMPs after ozonation with normalized dose of 1.25 mg O₃/mg DOC, and the removal of OMPs was consistent well with the second reaction kinetics constants of OMPs with ozone. Based on Pearson correlation analysis, spectroscopy indicators such as UV₂₅₄ and total fluorescence (TF) exhibited a high positive correlation with genotoxicity reduction, while estrogenic activity was related well with OMPs variation. To sum up, spectroscopic indicators showed a high potential to indicate the OMPs and bio-toxicity of SE.

Evolution of molecular weight and fluorescence of effluent organic matter (EfOM) during oxidation processes revealed by advanced spectrographic and chromatographic tools

Effluent organic matter (EfOM) is an emerging concern to receiving aquatic environment due to its refractory property. The degradation of EfOM in ozonation and other two advanced oxidation processes (AOPs), UV/H₂O₂ and UV/persulfate (PS), was investigated in this study. Fluorescence spectra coupled with parallel factor analysis (PARAFAC) and two-dimensional correlation gel permeation chromatography (2D-GPC) were used to track the evolution of EfOM during each oxidation process. Results showed that the degradation of EfOM indicated by dissolved organic carbon (DOC), UV₂₅₄ and fluorescence components, fitted well with pseudo-first-order kinetic model during the oxidation processes. Ozonation showed higher degradation efficiency than AOPs, while UV/PS was more effective than UV/H₂O₂ with equimolar oxidants dosage. Ozone and SO·₄^- were more reactive with terrestrial humic-like substances, while hydroxyl radical preferentially reacted with protein-like substances. Organic molecules with higher molecular weight (MW) were susceptible to ozone or radicals. Ozonation could transform higher MW (MW of 3510 and 575) organic matters into lower MW organic matters (MW of 294), while reductions of all the organics were observed in both AOPs. Due to the higher reaction rates between ozone and EfOM, ozonation maybe serve as a pre-treatment for AOPs to reduce the radical and energy consumption and improve mineralization of EfOM by AOPs. The decline in DOC, UV₂₅₄, fluorescence and reduction in oxidants increased with the increase of oxidants dosage, and linear correlations among them were found during the ozonation and AOPs.

Enhanced treatment of secondary municipal wastewater effluent: comparing (biological) filtration and ozonation in view of micropollutant removal, unselective effluent toxicity, and the potential for real-time control

Ozonation and three (biological) filtration techniques (trickling filtration (TF), slow sand filtration (SSF) and biological activated carbon (BAC) filtration) have been evaluated in different combinations as tertiary treatment for municipal wastewater effluent. The removal of 18 multi-class pharmaceuticals, as model trace organic contaminants (TrOCs), has been studied. (Biological) activated carbon filtration could reduce the amount of TrOCs significantly (>99%) but is cost-intensive for full-scale applications. Filtration techniques mainly depending on biodegradation mechanisms (TF and SSF) are found to be inefficient for TrOCs removal as a stand alone technique. Ozonation resulted in 90% removal of the total amount of quantified TrOCs, but a post-ozonation step is needed to cope with an increased unselective toxicity. SSF following ozonation showed to be the only technique able to reduce the unselective toxicity to the same level as before ozonation. In view of process control, innovative correlation models developed for the monitoring and control of TrOC removal during ozonation, are verified for their applicability during ozonation in combination with TF, SSF or BAC. Particularly for the poorly ozone reactive TrOCs, statistically significant models were obtained that correlate TrOC removal and reduction in UVA₂₅₄ as an online measured surrogate parameter.

Application of ozonation for pharmaceuticals and personal care products removal from water

Due to the shortening on natural water resources, reclaimed wastewater will be an important water supply source. However, suitable technologies must be available to guaranty its proper detoxification with special concern for the emerging pharmaceutical and personal care products that are continuously reaching municipal wastewater treatment plants. While conventional biological systems are not suitable to remove these compounds, ozone, due to its interesting features involving molecular ozone oxidation and the possibility of generating unselective hydroxyl radicals, has a wider range of action on micropollutants removal and water disinfection. This paper aims to review the studies dealing with ozone based processes for water reuse by considering municipal wastewater reclamation as well as natural and drinking water treatment. A comparison with alternative technologies is given. The main drawback of ozonation is related with the low mineralization achieved that may lead to the production of reaction intermediates with toxic features. The use of hydrogen peroxide and light aided systems enhance ozone action over pollutants. Moreover, scientific community is focused on the development of solid catalysts able to improve the mineralization level achieved by ozone. Special interest is now being given to solar light catalytic ozonation systems with interesting results both for chemical and biological contaminants abatement. Nowadays the integration between ozonation and sand biofiltration seems to be the most interesting cost effective methodology for water treatment. However, further studies must be performed to optimize this system by understanding the biofiltration mechanisms.

Determination of pharmaceutical residues and assessment of their removal efficiency at the Daugavgriva municipal wastewater treatment plant in Riga, Latvia

Pharmaceutical products (PPs) belong to emerging contaminants that may accumulate along with other chemical pollutants in wastewaters (WWs) entering industrial and/or urban wastewater treatment plants (WWTPs). In the present study, the technique of ultra-high-performance liquid chromatography coupled to Orbitrap high-resolution mass spectrometry (Orbitrap-HRMS) was applied for the analysis of 24 multi-class PPs in WW samples collected at different technological stages of Daugavgriva WWTP located in Riga, Latvia. Caffeine and acetaminophen levels in the range of 7,570-11,403 ng/L and 810-1,883 ng/L, respectively, were the predominant compounds among 19 PPs determined in the WW. The results indicate that aerobic digestion in biological ponds was insufficiently effective to degrade most of the PPs (reduction efficiency <0-50.0%) with the exception of four PPs that showed degradation efficiency varying from 55.0 to 99.9%. Tests of short-term chemical and enzymatic hydrolysis for PP degradation in WW samples were performed, and the results reflected the complexity of different degradation mechanisms and physicochemical transformations of PPs. The toxicological studies of WW impact on Daphnia magna indicated gradual reduction of the total toxicity through the treatment stages at the WWTP.

Impact of untreated wastewater on a major European river evaluated with a combination of in vitro bioassays and chemical analysis

Complex mixtures of micropollutants, including pesticides, pharmaceuticals and industrial chemicals emitted by wastewater effluents to European rivers may compromise the quality of these water resources and may pose a risk to ecosystem health and abstraction of drinking water. In the present study, an integrated analytical and bioanalytical approach was applied to investigate the impact of untreated wastewater effluents from the city of Novi Sad, Serbia, into the River Danube. The study was based on three on-site large volume solid phase extracted water samples collected upstream and downstream of the untreated wastewater discharge. Chemical screening with liquid chromatography high resolution mass spectrometry (LC-HRMS) was applied together with a battery of in vitro cell-based bioassays covering important steps of the cellular toxicity pathway to evaluate effects on the activation of metabolism (arylhydrocarbon receptor AhR, peroxisome proliferator activated receptor gamma PPARγ), specific modes of action (estrogen receptor ERα, androgen receptor AR) and adaptive stress responses (oxidative stress, inflammation). Increased effects, significantly changed contamination patterns and higher chemical concentrations were observed downstream of the wastewater discharge. A mass balance approach showed that enhanced endocrine disruption was in good agreement with concentrations of detected hormones, while only a smaller fraction of the effects on xenobiotic metabolism (<1%) and adaptive stress responses (0-12%) could be explained by the detected chemicals. The chemical and effects patterns observed upstream of the discharge point were fairly re-established at about 7 km downstream, demonstrating the enormous dilution capacity of this large river.

Advancing Biological Wastewater Treatment: Extended Anaerobic Conditions Enhance the Removal of Endocrine and Dioxin-like Activities

Conventional activated sludge treatment of wastewater does not completely remove micropollutants. Here, extending anaerobic conditions may enhance biodegradation. To explore this, we combined iron-reducing or substrate-limiting and aerobic pilot-scale reactors directly at a wastewater treatment plant. To assess the removal of endocrine disrupting chemicals (EDCs) as group of micropollutants that adversely affects wildlife, we applied a bioanalytical approach. We used in vitro bioassays covering seven receptor-mediated mechanisms of action, including (anti)androgenicity, (anti)estrogenicity, retinoid-like, and dioxin-like activity. Untreated wastewater induced antiandrogenic, estrogenic, antiestrogenic, and retinoid-like activity. Full-scale as well as reactor-scale activated sludge treatment effectively removes the observed effects. Nevertheless, high antiandrogenic and minor dioxin-like and estrogenic effects persisted in the treated effluent that may still be environmentally relevant. The anaerobic post-treatment under substrate-limiting conditions resulted in an additional removal of endocrine activities by 17-40%. The anaerobic pre-treatment under iron-reducing conditions significantly enhanced the removal of the residual effects by 40-75%. In conclusion, this study demonstrates that a further optimization of biological wastewater treatment is possible. Here, implementing iron-reducing anaerobic conditions preceding aerobic treatment appears promising to improve the removal of receptor-mediated toxicity.

Pilot-scale UV/H2O2 advanced oxidation process for municipal reuse water: Assessing micropollutant degradation and estrogenic impacts on goldfish (Carassius auratus L.)

Low concentrations (ng/L-μg/L) of emerging micropollutant contaminants in municipal wastewater treatment plant effluents affect the possibility to reuse these waters. Many of those micropollutants elicit endocrine disrupting effects in aquatic organisms resulting in an alteration of the endocrine system. A potential candidate for tertiary municipal wastewater treatment of these micropollutants is ultraviolet (UV)/hydrogen peroxide (H2O2) as an advanced oxidation process (AOP) which was currently applied to treat the secondary effluent of the Gold Bar Wastewater Treatment Plant (GBWWTP) in Edmonton, AB, Canada. A new approach is presented to predict the fluence-based degradation rate constants (kf') of environmentally occurring micropollutants including carbamazepine [(0.87-1.39) × 10(-3) cm(2)/mJ] and 2,4-Dichlorophenoxyacetic acid (2,4-D) [(0.60-0.91) × 10(-3) cm(2)/mJ for 2,4-D] in a medium pressure (MP) UV/H2O2 system based on a previous bench-scale investigation. Rather than using removal rates, this approach can be used to estimate the performance of the MP UV/H2O2 process for degrading trace contaminants of concern found in municipal wastewater. In addition to the ability to track contaminant removal/degradation, evaluation of the MP UV/H2O2 process was also accomplished by identifying critical ecotoxicological endpoints (i.e., estrogenicity) of the treated wastewater. Using quantitative PCR, mRNA levels of estrogen-responsive (ER) genes ERα1, ERα2, ERβ1, ERβ2 and NPR as well as two aromatase encoding genes (CYP19a and CYP19b) in goldfish (Carassius auratus L.) were measured during exposure to the GBWWTP effluent before and after MP UV/H2O2 treatment (a fluence of 1000 mJ/cm(2) and 20 mg/L of H2O2) in spring, summer and fall. Elevated expression of estrogen-responsive genes in goldfish exposed to UV/H2O2 treated effluent (a 7-day exposure) suggested that the UV/H2O2 process may induce acute estrogenic disruption to goldfish principally because of the possible formation of various oxidation by-products. However, prolonged exposure of goldfish (60 days) in UV/H2O2 treated effluent showed a restoration trend of ER gene expressions, especially in the summer. Collectively, our findings provide valuable indications regarding the long-term in vivo assessment of the MP UV/H2O2 process for removing/degrading endocrine disrupting compounds detected in the municipal wastewater effluents.

Probabilistic ecological risk assessment of effluent toxicity of a wastewater reclamation plant based on process modeling

The growing use of reclaimed wastewater for environmental purposes such as stream flow augmentation requires comprehensive ecological risk assessment and management. This study applied a system analysis approach, regarding a wastewater reclamation plant (WRP) and its recipient water body as a whole system, and assessed the ecological risk of the recipient water body caused by the WRP effluent. Instead of specific contaminants, two toxicity indicators, i.e. genotoxicity and estrogenicity, were selected to directly measure the biological effects of all bio-available contaminants in the reclaimed wastewater, as well as characterize the ecological risk of the recipient water. A series of physically based models were developed to simulate the toxicity indicators in a WRP through a typical reclamation process, including ultrafiltration, ozonation, and chlorination. After being validated against the field monitoring data from a full-scale WRP in Beijing, the models were applied to simulate the probability distribution of effluent toxicity of the WRP through Latin Hypercube Sampling to account for the variability of influent toxicity and operation conditions. The simulated effluent toxicity was then used to derive the predicted environmental concentration (PEC) in the recipient stream, considering the variations of the toxicity and flow of the upstream inflow as well. The ratio of the PEC of each toxicity indicator to its corresponding predicted no-effect concentration was finally used for the probabilistic ecological risk assessment. Regional sensitivity analysis was also performed with the developed models to identify the critical control variables and strategies for ecological risk management.

The assessment of WWTP performance: Towards a jigsaw puzzle evaluation?

A chemical and bio-analytical protocol is proposed as a holistic monitoring framework for the assessment of WWTPs (Wastewater Treatment Plants) performance. This combination of tests consists of: i) an analysis of emerging contaminants, to be added to the established physico-chemical parameters in order to understand the causes of (new) pollution phenomena and ii) some of the bio-analytical tools most widely applied in the field of wastewater research, which provide information on groups of chemicals with a common mode of toxic action (baseline toxicity, estrogenicity and mutagenicity/genotoxicity, selected as the most representative for human health). The negative effects of the discharge can thus be highlighted directly and used to assess the global environmental impact of WWTPs. As a validation, this multi-tiered approach was applied to a full-scale WWTP (150,000 p.e.), where different measurements were carried out: EDCs (Endocrine Disrupting Compounds) detection; algal growth inhibition, bioluminescence inhibition and acute toxicity test (for baseline toxicity); an E-Screen-like assay (for estrogenic activity); Ames, Allium cepa and Comet tests (for mutagenic/genotoxic activity). As a result, the WWTP showed good performance for all these issues, displaying its ability to enhance effluent quality, except for residual mutagenic behaviour, probably due to the by-products generated by the tertiary ozonation.

Removal of micropollutants through a biological wastewater treatment plant in a subtropical climate, Queensland-Australia

BACKGROUND

Municipal wastewaters contain a multitude of organic compounds derived from domestic and industrial sources including active components of pharmaceutical and personal care products and compounds used in agriculture, such as pesticides, or food processing such as artificial sweeteners often referred to as micropollutants. Some of these compounds or their degradation products may have detrimental effects on the environment, wildlife and humans. Acesuflame is one of the most popular artificial sweeteners to date used in foodstuffs. The main objectives of this descriptive study were to evaluate the presence of micropollutants in both the influent and effluent of a large-scale conventional biological wastewater treatment plant (WWTP) in South-East Queensland receiving wastewater from households, hospitals and various industries.

METHODS

Based on USEPA Method 1694: Filtered samples were spiked with mass-labelled chemical standards and then analysed for the micropollutants using liquid chromatography coupled with tandem mass spectrometry.

RESULTS

The presence of thirty-eight compounds were detected in the wastewater influent to the treatment plant while nine of the compounds in the categories of analgesic, anti-inflammatory, alkaloid and lipid/cholesterol lowering drugs were undetectable (100 % removed) in the effluent. They were: Analgesic: Paracetamol, Salicylic acid, Oxycodone; Anti-inflammatory: Naproxen + ve, Atorvastatin, Indomethacin, Naproxen; Alkaloid: Caffeine; Lipid/cholesterol lowering: Gemfibrozol.

CONCLUSIONS

The study results revealed that the micropollutants removal through this biological treatment process was similar to previous research reported from other countries including Europe the Americas and Asia, except for acesulfame, a highly persistent artificial sweetener. Surprisingly, acesulfame was diminished to a much greater extent (>90 %) than previously reported research for this type of WWTPs (45-65 %) that only include physical removal of objects and solids and a biodegradation step.

Wastewater compounds in urban shallow groundwater wells correspond to exfiltration probabilities of nearby sewers

Wastewater compounds are frequently detected in urban shallow groundwater. Sources include sewage or reclaimed wastewater, but origins are often unknown. In a prior study, wastewater compounds were quantified in waters sampled from shallow groundwater wells in a small coastal California city. Here, we resampled those wells and expanded sample analyses to include sewage- or reclaimed water-specific indicators, i.e. pharmaceutical and personal care product chemicals or disinfection byproducts. Also, we developed a geographic information system (GIS)-based model of sanitary sewer exfiltration probability--combining a published pipe failure model accounting for sewer pipe size, age, materials of construction, with interpolated depths to groundwater--to determine if sewer system attributes relate to wastewater compounds in urban shallow groundwater. Across the wells, groundwater samples contained varying wastewater compounds, including acesulfame, sucralose, bisphenol A, 4-tert-octylphenol, estrone and perfluorobutanesulfonic acid (PFBS). Fecal indicator bacterial concentrations and toxicological bioactivities were less than known benchmarks. However, the reclaimed water in this study was positive for all bioactivity tested. Excluding one well intruded by seawater, the similarity of groundwater to sewage, based on multiple indicators, increased with increasing sanitary sewer exfiltration probability (modeled from infrastructure within ca. 300 m of each well). In the absence of direct exfiltration or defect measurements, sewer exfiltration probabilities modeled from the collection system's physical data can indicate potential locations where urban shallow groundwater is contaminated by sewage.

Bioanalytical evidence that chemicals in tattoo ink can induce adaptive stress responses

Tattooing is becoming increasingly popular, particularly amongst young people. However, tattoo inks contain a complex mixture of chemical impurities that may pose a long-term risk for human health. As a first step towards the risk assessment of these complex mixtures we propose to assess the toxicological hazard potential of tattoo ink chemicals with cell-based bioassays. Targeted modes of toxic action and cellular endpoints included cytotoxicity, genotoxicity and adaptive stress response pathways. The studied tattoo inks, which were extracted with hexane as a proxy for the bioavailable fraction, caused effects in all bioassays, with the red and yellow tattoo inks having the greatest response, particularly inducing genotoxicity and oxidative stress response endpoints. Chemical analysis revealed the presence of polycyclic aromatic hydrocarbons in the tested black tattoo ink at concentrations twice the recommended level. The detected polycyclic aromatic hydrocarbons only explained 0.06% of the oxidative stress response of the black tattoo ink, thus the majority of the effect was caused by unidentified components. The study indicates that currently available tattoo inks contain components that induce adaptive stress response pathways, but to evaluate the risk to human health further work is required to understand the toxicokinetics of tattoo ink chemicals in the body.

Potential contribution of inorganic ions to whole effluent acute toxicity and genotoxicity during sewage tertiary treatment

Two acute toxicity tests (luminescent bacteria assay and cladoceran assay) and one genotoxicity test (broad bean assay) were used to evaluate whole effluent toxicity during the standard anion exchange resin-based pilot-scale sewage tertiary treatment that stably achieved significant dissolved organic carbon and inorganic ions reduction. The effect of six representative inorganic ions (i.e., Cl(-), SO4(2-), NO3(-)-N, NO2(-)-N, NH4(+)-N and PO4(3-)-P) on the acute toxicity and genotoxicity was further investigated. Significant whole effluent genotoxicity reduction was observed as an ∼ 57% micronucleated cell frequency reduction and ∼ 46% mitotic index increment during the pilot-scale periods, which should be attributed to significant organic removal since no significant (p ≥ 0.116) increase in genotoxicity was observed with the increase in these ionic concentrations. However, no significant (p ≥ 0.14) reductions were observed for whole effluent acute toxicity using two acute toxicity assays during the pilot-scale periods, and these inorganic ions, especially NH4(+)-N, contributed considerably to the acute toxicity. Based on Pearson correlation coefficients, whole effluent acute toxicity showed significant positive (p < 0.001, r ≥ 0.758) correlations with the NH4(+)-N concentration. Two optimal models were finally developed using step-wise multiple linear regression to predict the whole effluent acute toxicity via NH4(+)-N concentrations.

In vitro bioassays to evaluate complex chemical mixtures in recycled water

With burgeoning population and diminishing availability of freshwater resources, the world continues to expand the use of alternative water resources for drinking, and the quality of these sources has been a great concern for the public as well as public health professionals. In vitro bioassays are increasingly being used to enable rapid, relatively inexpensive toxicity screening that can be used in conjunction with analytical chemistry data to evaluate water quality and the effectiveness of water treatment. In this study, a comprehensive bioassay battery consisting of 36 bioassays covering 18 biological endpoints was applied to screen the bioactivity of waters of varying qualities with parallel treatments. Samples include wastewater effluent, ultraviolet light (UV) and/or ozone advanced oxidation processed (AOP) recycled water, and infiltrated recycled groundwater. Based on assay sensitivity and detection frequency in the samples, several endpoints were highlighted in the battery, including assays for genotoxicity, mutagenicity, estrogenic activity, glucocorticoid activity, arylhydrocarbon receptor activity, oxidative stress response, and cytotoxicity. Attenuation of bioactivity was found to be dependent on the treatment process and bioassay endpoint. For instance, ozone technology significantly removed oxidative stress activity, while UV based technologies were most efficient for the attenuation of glucocorticoid activity. Chlorination partially attenuated genotoxicity and greatly decreased herbicidal activity, while groundwater infiltration efficiently attenuated most of the evaluated bioactivity with the exception of genotoxicity. In some cases, bioactivity (e.g., mutagenicity, genotoxicity, and arylhydrocarbon receptor) increased following water treatment, indicating that transformation products of water treatment may be a concern. Furthermore, several types of bioassays with the same endpoint were compared in this study, which could help guide the selection of optimized methods in future studies. Overall, this research indicates that a battery of bioassays can be used to support decision-making on the application of advanced water treatment processes for removal of bioactivity.

Novel test procedure to evaluate the treatability of wastewater with ozone

Organic micropollutants such as pharmaceuticals, estrogens or pesticides enter the environment continuously through the effluent of municipal wastewater treatment plants (WWTPs). Enhanced treatment of wastewater (WW) by ozone (O3) is probably one of the simplest measures for abatement of organic micropollutants to avoid their discharge to the aquatic environment. During ozonation most organic micropollutants present in treated WW are oxidized either by a direct reaction with O3 or by secondarily formed hydroxyl radicals (OH). However, undesired oxidation by-products from the oxidative transformation of matrix components can also be formed. A modular laboratory decision tool based on the findings of previous investigations is presented to test the feasibility of ozonation as an option to upgrade specific WWTPs. These modules consist of investigations to assess (i) the matrix effects on ozone stability, (ii) the efficiency of micropollutant removal, (iii) the oxidation by-product formation, as well as (iv) bioassays to measure specific and unspecific toxicity of the treated WWs. Matrix effects on ozone stability (quantified as O3 and OH exposures) can give first indications on the suitability of an ozonation step. Ozonation of WWs yielding O3 and OH exposures and micropollutant abatement similar to reference values evoked a significant improvement of the water quality as indicated by a broad range of bioassays. Irregular behavior of the ozonation points towards unknown compounds, possibly leading to the formation of undesired degradation products. It has been observed that in such WWs ozonation partly enhanced toxicity. In summary, the presented tiered laboratory test procedure represents a relatively cheap and straight-forward methodology to evaluate the feasibility of ozonation to upgrade specific WWTPs for micropollutant removal based on chemical and biological measurements.

A sensitive and high throughput bacterial luminescence assay for assessing aquatic toxicity--the BLT-Screen

Bioassays using naturally luminescent bacteria are commonly used to assess the toxicity of environmental contaminants, detected by a decrease in luminescence. Typically, this has involved the use of commercial test kits such as Microtox and ToxScreen. These commercial assays, however, have limitations for routine environmental monitoring, including the need for specialized equipment, a low throughput and high on-going costs. There is therefore a need to develop a bacteria bioassay that is sensitive, high-throughput and cost effective. This study presents the development and application of the BLT-Screen (Bacterial Luminescence Toxicity Screen), a 96-well plate bioassay using Photobacterium leiognathi. During development of the method, the concentration of the phosphate buffer in the experimental medium was adjusted to maximize the sensitivity of the assay, and protocols for analyzing both solid-phase extracts and raw water samples were established. A range of organic compounds and metals were analyzed in the assay, as well as extracts of various water samples, including drinking water, wastewater effluent and river water. The IC50 values of the organic compounds and metals tested in the BLT-Screen were comparable to previously published ToxScreen and Microtox data. In addition, the assay was sensitive enough to detect toxicity in all water types tested, and performed equally well for both solid-phase extracts and raw water samples. The BLT-Screen therefore presents a cost-effective, sensitive and high throughput method for testing the toxicity of environmental contaminants in a range of water types that has widespread applications for research, as well as for routine monitoring and operation of wastewater and drinking water plants.

Tailoring the optical properties of ZnO nano-layers and their effect on in vitro biocompatibility

This paper highlights the use of Al₂O₃ and SnO₂ films as protecting layers to tailor the optical properties and biocompatibility of ZnO nano-films.

Prediction of micropollutant elimination during ozonation of a hospital wastewater effluent

Determining optimal ozone doses for organic micropollutant elimination during wastewater ozonation is challenged by the presence of a large number of structurally diverse micropollutants for varying wastewater matrice compositions. A chemical kinetics approach based on ozone and hydroxyl radical (·OH) rate constant and measurements of ozone and ·OH exposures is proposed to predict the micropollutant elimination efficiency. To further test and validate the chemical kinetics approach, the elimination efficiency of 25 micropollutants present in a hospital wastewater effluent from a pilot-scale membrane bioreactor (MBR) were determined at pH 7.0 and 8.5 in bench-scale experiments with ozone alone and ozone combined with H2O2 as a function of DOC-normalized specific ozone doses (gO3/gDOC). Furthermore, ozone and ·OH exposures, ·OH yields, and ·OH consumption rates were determined. Consistent eliminations as a function of gO3/gDOC were observed for micropollutants with similar ozone and ·OH rate constants. They could be classified into five groups having characteristic elimination patterns. By increasing the pH from 7.0 to 8.5, the elimination levels increased for the amine-containing micropollutants due to the increased apparent second-order ozone rate constants while decreased for most micropollutants due to the diminished ozone or ·OH exposures. Increased ·OH quenching by effluent organic matter and carbonate with increasing pH was responsible for the lower ·OH exposures. Upon H2O2 addition, the elimination levels of the micropollutants slightly increased at pH 7 (<8%) while decreased considerably at pH 8.5 (up to 31%). The elimination efficiencies of the selected micropollutants could be predicted based on their ozone and ·OH rate constants (predicted or taken from literature) and the determined ozone and ·OH exposures. Reasonable agreements between the measured and predicted elimination levels were found, demonstrating that the proposed chemical kinetics method can be used for a generalized prediction of micropollutant elimination during wastewater ozonation. Out of 67 analyzed micropollutants, 56 were present in the tested hospital wastewater effluent. Two-thirds of the present micropollutants were found to be ozone-reactive and efficiently eliminated at low ozone doses (e.g., >80% for gO3/gDOC = 0.5).

Water exposure assessment of aryl hydrocarbon receptor agonists in Three Gorges Reservoir, China using SPMD-based virtual organisms

SPMD-based virtual organisms (VOs) were deployed at five to eight sites in the Three Gorges Reservoir (TGR), China for five periods in 2008, 2009 and 2011. The water exposure of aryl hydrocarbon receptor (AhR) agonists was assessed by the VOs. The chosen bioassay response for the extracts of the VOs, the induction of 7-ethoxyresorufin-O-deethylase (EROD) was assayed using a rat hepatoma cell line (H4IIE). The results show that the extracts from the VOs could induce AhR activity significantly, whereas the chemically derived 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent (TEQcal) accounted for <11% of the observed AhR responses (TEQbio). Unidentified AhR-active compounds represented a greater proportion of the TCDD equivalent in VOs from TGR. High TEQbio value in diluted extract and low TEQbio in concentrated extract of the same sample was observed suggesting potential non-additive effects in the mixture. The levels of AhR agonists in VOs from upstream TGR were in general higher than those from downstream reservoir, indicating urbanization effect on AhR agonist pollution. The temporal variation showed that levels of AhR agonists in 2009 and 2011 were higher than those in 2008, and the potential non-additive effects in the area close to the dam were also obviously higher in 2009 and 2011 than in 2008, indicating big changes in the composition of pollutants in the area after water level reached a maximum of 175 m. Although the aqueous concentration of AhR agonists of 0.8-4.8 pg TCDDL(-1) in TGR was not alarming, the tendency of accumulating high concentration of AhR agonists in VO lipid and existence of possible synergism or antagonism in the water may exhibit a potential hazard to local biota being exposed to AhR agonists.

Combined chemical and toxicological long-term monitoring for AhR agonists with SPMD-based virtual organisms in drinking water Danjiangkou Reservoir, China

SPMD-based virtual organisms (VOs) were employed for time-integrating, long-term sampling combined biological and chemical analyses for exposure assessment of hydrophobic organic pollutants (HOPs) in a drinking water reservoir, China. The SPMDs were deployed at four and five sites in the Danjiangkou (DJK) reservoir over two periods of 26 and 31 d to sequester the hydrophobic contaminants in water. The chosen bioassay response for the extracts of the SPMDs, the induction of 7-ethoxyresorufin-o-deethylase (EROD) was assayed using a rat hepatoma cell line (H4IIE). The known aryl hydrocarbon receptor (AhR) agonists PAHs and PCBs were analyzed by HRGC/HRMS instrument. The cause-effect relationship between the observed AhR activities and chemical concentrations of detected AhR agonists was examined. The results show that the extracts from the SPMD samples could induce AhR activity significantly, whereas the chemically derived 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent (TEQcal) was not correlated with the bioassay-derived TCDD equivalent (TEQbio). The known AhR agonists could only account for 2-10% of the observed AhR responses among which the contribution of PCBs could almost be neglected. Unidentified AhR-active compounds represented a greater proportion of the TCDD equivalent (TCDD-EQ) in SPMD samples from DJK. Based on the first assessment, the VO followed by the combination of chemical and biological analyses emerges as a resource efficient water monitoring device in ecotoxicological assessment for toxicologically relevant compounds which are readily available for uptake by resident aquatic biota in drinking water resources.

Does co-extracted dissolved organic carbon cause artefacts in cell-based bioassays?

Bioanalytical tools are increasingly being employed for water quality monitoring, with applications including samples that are rich in natural organic matter (or dissolved organic carbon, DOC), such as wastewater. While issues associated with co-extracted DOC have been identified for chemical analysis and for bioassays with isolated enzymes, little is known about its effect on cell-based bioassays. Using mixture experiments as diagnostic tools, this study aims to assess whether different molecular weight fractions of wastewater-derived DOC adversely affect cell-based bioassays, specifically the bioluminescence inhibition test with the bacteria Vibrio fischeri, the combined algae assay with Pseudokirchneriella subcapitata and the human cell line AREc32 assay for oxidative stress. DOC did not cause suppressive effects in mixtures with reference compounds. Binary mixtures further indicated that co-extracted DOC did not disturb cell-based bioassays, while slight deviations from toxicity predictions for low molecular weight fractions may be partially due to the availability of natural components to V. fischeri, in addition to organic micropollutants.

Realistic environmental mixtures of micropollutants in surface, drinking, and recycled water: herbicides dominate the mixture toxicity toward algae

Mixture toxicity studies with herbicides have focused on a few priority components that are most likely to cause environmental impacts, and experimental mixtures were often designed as equipotent mixtures; however, real-world mixtures are made up of chemicals with different modes of toxic action at arbitrary concentration ratios. The toxicological significance of environmentally realistic mixtures has only been scarcely studied. Few studies have simultaneously compared the mixture effect of water samples with designed reference mixtures comprised of the ratios of analytically detected concentrations in toxicity tests. In the present study, the authors address the effect of herbicides and other chemicals on inhibition of photosynthesis and algal growth rate. The authors tested water samples including secondary treated wastewater effluent, recycled water, drinking water, and storm water in the combined algae assay. The detected chemicals were mixed in the concentration ratios detected, and the biological effects of the water samples were compared with the designed mixtures of individual detected chemicals to quantify the fraction of effect caused by unknown chemicals. The results showed that herbicides dominated the algal toxicity in these environmentally realistic mixtures, and the contribution by the non-herbicides was negligible. A 2-stage model, which used concentration addition within the groups of herbicides and non-herbicides followed by the model of independent action to predict the mixture effect of the two groups, could predict the experimental mixture toxicity effectively, but the concentration addition model for herbicides was robust and sufficient for complex mixtures. Therefore, the authors used the bioanalytical equivalency concept to derive effect-based trigger values for algal toxicity for monitoring water quality in recycled and surface water. All water samples tested would be compliant with the proposed trigger values associated with the appropriate guidelines.