Source apportionment of trace contaminants in urban sewer catchments

Impact of environment on transmission of antibiotic-resistant superbugs in humans and strategies to lower dissemination of antibiotic resistance

Antibiotics are the most efficient type of therapy developed in the twentieth century. From the early 1960s to the present, the rate of discovery of new and therapeutically useful classes of antibiotics has significantly decreased. As a result of antibiotic use, novel strains emerge that limit the efficiency of therapies in patients, resulting in serious consequences such as morbidity or mortality, as well as clinical difficulties. Antibiotic resistance has created major concern and has a greater impact on global health. Horizontal and vertical gene transfers are two mechanisms involved in the spread of antibiotic resistance genes (ARGs) through environmental sources such as wastewater treatment plants, agriculture, soil, manure, and hospital-associated area discharges. Mobile genetic elements have an important part in microbe selection pressure and in spreading their genes into new microbial communities; additionally, it establishes a loop between the environment, animals, and humans. This review contains antibiotics and their resistance mechanisms, diffusion of ARGs, prevention of ARG transmission, tactics involved in microbiome identification, and therapies that aid to minimize infection, which are explored further below. The emergence of ARGs and antibiotic-resistant bacteria (ARB) is an unavoidable threat to global health. The discovery of novel antimicrobial agents derived from natural products shifts the focus from chemical modification of existing antibiotic chemical composition. In the future, metagenomic research could aid in the identification of antimicrobial resistance genes in the environment. Novel therapeutics may reduce infection and the transmission of ARGs.

European-wide spatial analysis of sewage treatment plants and the possible benefits to nature of advanced treatment to reduce pharmaceutical emissions

Pharmaceuticals are known to widely occur in the environment and to affect the health of ecosystems. Sewage treatment plants (STPs) are main emission pathways for pharmaceuticals, which are often not sufficiently removed during wastewater treatment. In Europe, STP treatment requirements are specified under the Urban WasteWater Treatment Directive (UWWTD). The introduction of advanced treatment techniques, such as ozonation and activated carbon, under the UWWTD is expected to be an important option to reduce pharmaceutical emissions. In this study, we present a European-wide analysis of STPs reported under the UWWTD, their current treatment level and potential to remove a set of 58 prioritised pharmaceuticals. Three different scenarios were analysed to show 1) UWWTD present effectiveness, 2) the effectiveness at full UWWTD compliance, and 3) the effectiveness when advanced treatment is implemented at STPs with a treatment capacity of >100.000 person equivalents. Based on a literature study, the potential of individual STPs to reduce pharmaceutical emissions ranged from an average of 9% for STPs with primary treatment to 84% for STPs applying advanced treatment. Results of our calculations show that European-wide emission of pharmaceuticals can be reduced with 68% when large STPs are updated with advanced treatment, but spatial differences exist. We argue that adequate attention should also be paid with regards to preventing environmental impacts of STPs with a capacity <100.000 p.e. Circa 44% of total STP effluent is emitted near Natura2000 sites (EU nature protection areas). Of all surface waters receiving STP effluent for which the ecological status has been assessed under the Water Framework Directive, 77% have a status of less than good. Relatively often only primary treatment is applied to wastewater emitted into coastal waters. This analysis can be used to further model pharmaceutical concentrations in European surface waters, to identify STPs for which more advanced treatment might be required and to protect EU aquatic biodiversity.

Sources of copper into the European aquatic environment

Chemical contamination from point source discharges in developed (resource-rich) countries has been widely regulated and studied for decades; however, diffuse sources are largely unregulated and widespread. In the European Union (EU), large dischargers report releases of some chemicals, yet little is known of total emissions (point and diffuse) and their relative significance. We estimated copper loadings from all significant sources including industry, sewage treatment plants, surface runoff (from traffic, architecture, and atmospheric deposition), septic tanks, agriculture, mariculture, marine transport (antifoulant leaching), and natural processes. A combination of European datasets, literature, and industry data were used to generate export coefficients. These were then multiplied by activity rates to derive loads. A total of approximately 8 kt of copper per annum (ktpa) is estimated to enter freshwaters in the EU, and another 3.5 ktpa enters transitional and coastal waters. The main inputs to freshwater are natural processes (3.7 ktpa), agriculture (1.8 ktpa), and runoff (1.8 ktpa). Agricultural emissions are dominated by copper-based plant protection products and farmyard manure. Urban runoff is influenced by copper use in architecture and by vehicle brake linings. Antifoulant leaching from boats (3.2 ktpa) dominates saline water loads of copper. It is noteworthy that most of the emissions originate in a limited number of copper uses where environmental exposure and pathways exist, compared with the bulk of copper use within electrical and electronic equipment and infrastructure that has no environmental pathway during its use. A sensitivity analysis indicated significant uncertainty in data from abandoned mines and urban runoff load estimates. This study provided for the first time a methodology and comprehensive metal load apportionment to European aquatic systems, identifying data gaps and uncertainties, which may be refined over time. Source apportionments using this methodology can inform more cost-effective environmental risk assessment and management. Integr Environ Assess Manag 2022;00:1-17. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Micropollutants in urban wastewater: large-scale emission estimates and analysis of measured concentrations in the Baltic Sea catchment

Wastewater treatment plants (WWTPs) transmit many chemical contaminants to aquatic environments. Quantitative data on micropollutant emissions via WWTPs are needed for environmental risk assessments and evaluation of mitigation measures. This study compiled published data on substances analysed in effluents from WWTPs in the Baltic Sea region, assessed country related differences in the data sets and estimated micropollutant inputs to the Baltic Sea catchment. Concentration data were found for 1090 substances analysed at 650 WWTPs. Heterogeneity and low number of data points for most substances hindered adequate comparisons of country specific concentrations. Emission estimates were made for the 280 substances analysed in at least five WWTPs in years 2010 to 2019. For selected substances, mass loads were compared to previously published estimations. The study provides data useful for national and Baltic Sea-scale pressure analysis and risk assessments. However, it also highlights the need for broad scope monitoring of micropollutants in wastewater.

Effects of iron dosing used for phosphorus removal at wastewater treatment works; impacts on forms of phosphorus discharged and secondary effects on concentrations and fate of other contaminants

Iron dosing for phosphorus reduction during wastewater treatment is wide practised across the globe. However, the impacts of this dosing in terms of the speciation of phosphorus discharged and secondary effects on removing or introducing other trace elements from or into the effluent have not been studied. Results are presented for concentrations of a range of contaminants in over 600 wastewater treatment works, reported as mean concentration values derived from 20 effluent samples taken over a period of two years. Approximately half of the treatment works employed iron dosing to reduce concentrations of phosphorus in effluents. In addition to the expected effects on level of phosphorus discharged to surface waters, it is shown that these measures are shown to have unintended and beneficial consequences for concentrations of several other constituents of wastewater. Reductions of more than 40% in the concentrations of dissolved metals (copper, lead) benzo(a)pyrene and hexabromocyclododecane are observed. Lower but still significant decreases in concentration (>30%) are evident for dissolved cadmium, fluoranthene cypermethrin and biochemical oxygen demand. Small but less environmentally important increases are seen for iron and nickel, in the case of the latter this is presumably because nickel is a contaminant of the iron reagent used for dosing. These reductions are shown to offer significant benefits in terms of levels entering surface waters relating to the in-river environmental quality standards.

Tricks and tracks in removal of emerging contaminants from the wastewater through hybrid treatment systems: A review

In recent years, many biological and physicochemical treatment technologies have been investigated for the removal of the emerging contaminants (ECs) from the wastewater matrix. However, due to the deficiency of these treatments to completely degrade the ECs in wastewater, hybrid systems were explored using the distinguishing removal potential of the different treatment processes. This review gives an insight on such hybrid systems combining several physical, chemical and biological treatments for the fast and eco-efficient removal of ECs from wastewater. Most of the hybrid systems have applied biological treatments first and then physical or chemical treatments. The hybrid system of membrane bioreactor (MBR) followed by membrane filtrations (RO/NF) effectively removed a suite of ECs such as pharmaceuticals, beta blockers, pesticides and EDCs. Some of the hybrid systems of constructed wetlands and waste stabilization ponds showed promising potential for the biosorptive removal of pharmaceuticals and some beta blockers. The hybrid systems combining activated sludge process and physical processes such as ultrafiltration (UF), reverse osmosis (RO) and gamma radiations are considered as the cost effective technologies and had better removal of trace organic pollutants. The hybrid system of MBR coupled with UV oxidation, activated carbon and ultrasound, and ozonation followed by ultrasounds, completely degraded some ECs and many pharmaceuticals. The review also synthesizes the trend followed by the hybrid system processes for the removal of various categories of ECs. The future research directions for the ECs removal utilizing hybrid nanocomposites and green sustainable technology have been suggested.

Tracking emission sources of PAHs in a region with pollution-intensive industries, Taihu Basin: From potential pollution sources to surface water

The strict environmental management has been implemented in Taihu Basin to reduce the surface water contamination; however, the effectiveness of the management actions has not been comprehensively evaluated. In the present study, 364 samples were collected during four campaigns over a span of one year from surface water, municipal wastewater treatment plants (MWWTPs), industrial wastewater treatment plants (IWWTPs), industrial enterprises, and aquaculture in a typical region in the Upper Taihu Basin. Overall concentration, temporal variation and spatial distribution of 16 PAHs in surface water and various pollution sources were evaluated and the potential pollution sources were identified. Results showed that concentrations of individual PAHs in the surface water ranged from less than the limit of quantification (LOQ) to 949 ng L^-1, indicating a reduction of PAH contamination level after the implementation of environmental management actions. Influent of MWWTPs and wastewater from industrial enterprises exhibited relatively high ∑PAHs concentrations (mean: 880 ng L^-1 and 642 ng L^-1, respectively); these samples also exhibited a similar seasonal variation as well as composition of PAH congeners to those found in surface water, and therefore were designated as the main emission sources of PAHs in the studied region. Additional source apportionment using principal component analysis was also conducted to verify the proposed sources and diagnose other pollution sources. The findings provided a thorough understanding of PAH pollution, especially its major emission sources, in a typical region with pollution-intensive industries after the implementation of strict environmental management.

Seasonal variation of contaminant concentrations in wastewater treatment works effluents and river waters

Results are presented for 170 wastewater treatment works sites (20 per substance in influent, effluent and 36 per substance in river water upstream and downstream of the WwTW discharge) over a period of two years between 2015 and 2017; this comprises data for approximately 3000 samples for effluent and 6000 for river samples taken downstream of effluent discharges. Seasonal trends in contaminant concentrations for several substances are reported. Two clear patterns of seasonal variation are proposed over and above all of the variables associated with environmental data including process technology, dilution and geography. Firstly, variation of riverine concentrations caused by seasonal fluctuations in river flow (sewage flow being relatively consistent) resulting in summer maxima and winter minima. Alternatively, variation is observed that is attributable to the improved performance of wastewater treatment processes under warmer conditions. This leads to the lowest concentrations in autumn when surface water/sewage treatment temperatures tend to peak. Seasonality for trace contaminants is more difficult to characterise than that of sanitary parameters owing to the higher variability in the concentration of the substances of interest. The data also provide an insight into the amplitude of such variations. This makes it possible to assess the likely effects of seasonality and its impact on aquatic life. For example, the existence of seasonality (perhaps due only to dilution effects) might be demonstrated, but the amplitude might be too small in relation to the potential ecotoxicological effects to be of any consequence.

A pilot study on polycystic ovarian syndrome caused by neonatal exposure to tributyltin and bisphenol A in rats

The development of polycystic ovary syndrome (PCOS) could be caused by exposure to environmental endocrine disrupting chemicals (EDCs). In the current study, two commonly found EDCs, bisphenol A (BPA) and tributyltin (TBT), were investigated for their effects on PCOS occurrence in neonatal female rats. TBT (10 and 100 ng kg^-1 d^-1), BPA (50 μg kg^-1 d^-1), and a mixture of the two (TBT 100 ng kg^-1 d^-1 with BPA 50 μg kg^-1 d^-1) were administered to female rats from postnatal day 1-16. TBT, BPA, and TBT + BPA treatment resulted in an irregular estrus cycle and disturbed ovarian development, with less corpora lutea and antral follicles, but more atretic follicles and cysts. In addition, serum testosterone and luteinizing hormone levels were significantly elevated, whereas a reduced level of serum sex hormone-binding globulin was observed after TBT100, BPA50, and TBT + BPA treatments. Moreover, gene expression analyses identified significant differential expression of the genes involved in a variety of biological pathways, such as lipid transport and steroidogenesis. Moreover, the expression level of proteins regulating lipid and androgen biosynthesis was elevated after the treatments. In conclusion, this study demonstrated that exposure to TBT, BPA, and a mixture of the two in newborn rats could contribute to a PCOS-like syndrome. The mechanism of PCOS pathogenesis caused by exposure to TBT and BPA is likely to be mediated by the lipid metabolism and steroidogenesis pathways. Our results provide novel insight into female reproduction affected by EDCs, which may be helpful for revealing the pathogenesis of PCOS.

The removal of pharmaceuticals during wastewater treatment: Can it be predicted accurately?

The presence of active pharmaceutical ingredients (APIs) in the environment is of growing concern and effluents from wastewater treatment works (WwTWs) are one of the major sources. This research combines the outputs of a multimillion pound UK program of work to evaluate the fate of APIs in the wastewater treatment process. A combination of analysis of measured data and modelling has been applied to 18 APIs, representing a wide range of medicinal application and physico-chemical characteristics. Some isomers (for atorvastatin) and metabolites (for sertraline, carbamazepine and erythromycin) were also included. High variability was observed between removal rates for individual APIs between WwTW, which after statistical analysis could not be explained by the nominal WwTW process (e.g. activated sludge or trickling filter). Nor was there a clear relationship between API removal and physico-chemical parameters such as pKa, charge or log Kow. A publically available sewage process model, SimpleTreat 4.0 which has been rigorously validated and is now being used for exposure assessment with REACH legislation for organic chemicals and within the Biocidal Products Regulation by the European Medicines Agency for APIs, was used to estimate removal rates with which to compare with measured data. SimpleTreat provided estimates of removal rates within ±30% of observed values for the majority of the APIs measured, with the use of readily available WwTW specific parameters such as flow, total suspended solids and BOD data. The data and correlations provided in this study provide support for any future considerations regarding the management of API discharge to the aquatic environment.

Evaluation of combined sewer overflow impacts on short-term pharmaceutical and illicit drug occurrence in a heavily urbanised tidal river catchment (London, UK)

The occurrence of pharmaceutical and illicit drug residues potentially arising from combined sewer overflows (CSOs) in the Central London portion of the Thames Estuary is presented. Approximately 39 million tonnes of untreated sewage enter the River Thames at 57 CSO points annually. Differential analysis of influents and effluents in a major wastewater treatment plant identified seven potential drug-related CSO markers based on removal rates. Three were present in influent at concentrations >1 μg L^-1 (caffeine, cocaine and benzoylecgonine). During dry weather, analysis of hourly samples of river water revealed relatively consistent concentrations for most drugs, including CSO markers, over a tidal cycle. River water was monitored over a week in January and July and then daily across six consecutive weeks in November/December 2014. Out of 31 compounds monitored, 27 drug residues were determined in the River Thames and, combined, ranged between ~1000-3500 ng L^-1. Total drug concentration generally declined during extended periods of drier weather. For CSO markers, short-term increases in caffeine, cocaine and benzoylecgonine concentration were observed ~24 h after CSO events (especially those occurring at low tide) and generally within one order of magnitude. Timings of elevated occurrence also correlated well with ammonium ion and dissolved oxygen data following CSOs. This work also represents an important study of pharmaceutical occurrence before a major 'Super Sewer' infrastructure upgrade in London aiming to reduce CSOs by 95%.

Aquatic exposures of chemical mixtures in urban environments: Approaches to impact assessment

Urban regions of the world are expanding rapidly, placing additional stress on water resources. Urban water bodies serve many purposes, from washing and sources of drinking water to transport and conduits for storm drainage and effluent discharge. These water bodies receive chemical emissions arising from either single or multiple point sources, diffuse sources which can be continuous, intermittent, or seasonal. Thus, aquatic organisms in these water bodies are exposed to temporally and compositionally variable mixtures. We have delineated source-specific signatures of these mixtures for diffuse urban runoff and urban point source exposure scenarios to support risk assessment and management of these mixtures. The first step in a tiered approach to assessing chemical exposure has been developed based on the event mean concentration concept, with chemical concentrations in runoff defined by volumes of water leaving each surface and the chemical exposure mixture profiles for different urban scenarios. Although generalizations can be made about the chemical composition of urban sources and event mean exposure predictions for initial prioritization, such modeling needs to be complemented with biological monitoring data. It is highly unlikely that the current paradigm of routine regulatory chemical monitoring alone will provide a realistic appraisal of urban aquatic chemical mixture exposures. Future consideration is also needed of the role of nonchemical stressors in such highly modified urban water bodies. Environ Toxicol Chem 2018;37:703-714. © 2017 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Active pharmaceutical ingredients entering the aquatic environment from wastewater treatment works: A cause for concern?

This work reports on the variation in wastewater treatment works (WwTW) influent concentrations of a wide variety of active pharmaceutical ingredients (APIs), their removal efficiency, effluent concentrations and potential risks to the aquatic environment. The research is based on data generated from two large UK-wide WwTW monitoring programmes. Taking account of removal of parent compound from the aqueous phase during treatment in combination with estimates of dilution available it is possible to prioritise the APIs of greatest risk of exceeding estimates of predicted no effect concentrations (PNEC) in receiving waters for all WwTW in the UK. The majority of substances studied were removed to a high degree, although with significant variation, both within and between WwTW. Poorer removal (between influent and effluent) was observed for ethinyloestradiol, diclofenac, propranolol, the macrolide antibiotics, fluoxetine, tamoxifen and carbamazepine. All except the last two of these substances were present in effluents at concentrations higher than their respective estimated PNEC (based on measurement of effluents from 45 WwTW on 20 occasions). Based on available dilution data as many as 890 WwTW in the UK (approximately 13% of all WwTW) may cause exceedances of estimated riverine PNECs after mixing of their effluents with receiving waters. The overall degree of risk is driven by the toxicity value selected, which in itself is controlled by the availability of reliable and relevant ecotoxicological data and consequently the safety factors applied. The dataset and discussion, provides information to assist in the future management of these types of chemicals.

An analysis of variable dissolution rates of sacrificial zinc anodes: a case study of the Hamble estuary, UK

Sacrificial anodes are intrinsic to the protection of boats and marine structures by preventing the corrosion of metals higher up the galvanic scale through their preferential breakdown. The dissolution of anodes directly inputs component metals into local receiving waters, with variable rates of dissolution evident in coastal and estuarine environments. With recent changes to the Environmental Quality Standard (EQS), the load for zinc in estuaries such as the Hamble, UK, which has a large amount of recreational craft, now exceeds the zinc standard of 7.9 μg/l. A survey of boat owners determined corrosion rates and estimated zinc loading at between 6.95 and 7.11 t/year. The research confirms the variable anode corrosion within the Hamble and highlighted a lack of awareness of anode technology among boat owners. Monitoring and investigation discounted metal structures and subterranean power cables as being responsible for these variations but instead linked accelerated dissolution to marina power supplies and estuarine salinity variations.

Review of Antimicrobial Resistance in the Environment and Its Relevance to Environmental Regulators

The environment is increasingly being recognized for the role it might play in the global spread of clinically relevant antibiotic resistance. Environmental regulators monitor and control many of the pathways responsible for the release of resistance-driving chemicals into the environment (e.g., antimicrobials, metals, and biocides). Hence, environmental regulators should be contributing significantly to the development of global and national antimicrobial resistance (AMR) action plans. It is argued that the lack of environment-facing mitigation actions included in existing AMR action plans is likely a function of our poor fundamental understanding of many of the key issues. Here, we aim to present the problem with AMR in the environment through the lens of an environmental regulator, using the Environment Agency (England’s regulator) as an example from which parallels can be drawn globally. The issues that are pertinent to environmental regulators are drawn out to answer: What are the drivers and pathways of AMR? How do these relate to the normal work, powers and duties of environmental regulators? What are the knowledge gaps that hinder the delivery of environmental protection from AMR? We offer several thought experiments for how different mitigation strategies might proceed. We conclude that: (1) AMR Action Plans do not tackle all the potentially relevant pathways and drivers of AMR in the environment; and (2) AMR Action Plans are deficient partly because the science to inform policy is lacking and this needs to be addressed.

Presence of pharmaceuticals and heavy metals in the waters of a Mediterranean coastal wetland: Potential interactions and the influence of the environment

The occurrence of 17 relevant pharmaceuticals and 7 heavy metals in the waters of the Pego-Oliva Marsh Natural Park (Valencia Community, Spain) were monitored. Thirty four zones (including the lagoon and the most important irrigation channels), covering the main land uses and water sources, were selected for sampling. Thirty three of them were contaminated with at least one pharmaceutical. Ibuprofen and codeine were the pharmaceuticals more frequently detected, in concentrations between 4.8 and 1.2 ng/L and a maximum of 59 ng/L and 63 ng/L, respectively. Regarding metals, Zn showed values under the detection limit in all the samples, while Cd, Co, Cr, Cu, Ni and Pb were detected at concentrations lower than the WHO and EU maximum levels for drinking waters. Ni showed significant direct correlations with diazepam, norfloxacin, ofloxacin and fenofibrate, and inverse relationships with ibuprofen, at 99 and 95% of significance. Cu, Co and Cr also showed significant correlations with some of the pharmaceuticals. These interactions could favor the synergistic/antagonistic interactions among pharmaceuticals and metals in the marsh, which can affect its aquatic fauna and flora or even human health. The influences of the water sources, land uses and spatial distribution of both types of contaminants were also studied.

The impact of tertiary wastewater treatment on copper and zinc complexation

Tightening quality standards for European waters has seen a move towards enhanced wastewater treatment technologies such as granulated organic carbon treatment and ozonation. Although these technologies are likely to be successful in degrading certain micro-organic contaminants, these may also destroy compounds which would otherwise complex and render metals significantly less toxic. This study examined the impact of enhanced tertiary treatment on the capacity of organic compounds within sewage effluents to complex copper and zinc. The data show that granulated organic carbon treatment removes a dissolved organic carbon (DOC) fraction that is unimportant to complexation such that no detrimental impact on complexation or metal bioavailability is likely to occur from this treatment type. High concentrations of ozone (>1 mg O3/mg DOC) are, however, likely to impact the complexation capacity for copper although this is unlikely to be important at the concentrations of copper typically found in effluent discharges or in rivers. Ozone treatment did not affect zinc complexation capacity. The complexation profiles of the sewage effluents show these to contain a category of non-humic ligand that appears unaffected by tertiary treatment and which displays a high affinity for zinc, suggesting these may substantially reduce the bioavailability of zinc in effluent discharges. The implication is that traditional metal bioavailability assessment approaches such as the biotic ligand model may overestimate zinc bioavailability in sewage effluents and effluent-impacted waters.