Transformation and Sorption of Illicit Drug Biomarkers in Sewer Biofilms

Impact of long-term and short-term magnesium hydroxide dosing on transformation of chemical biomarkers in the sewer systems

Magnesium hydroxide (Mg(OH)₂) dosing is widely applied for sewer odour control. However, its impact on the fate of biomarkers used for wastewater-based epidemiology (WBE) has been overlooked. This study investigated the long-term and short-term impact of Mg(OH)₂ dosing on in-sewer transformation of 20 biomarkers. The dosing duration and amount of Mg(OH)₂ were specifically controlled in laboratory-scale sewer reactors, which led to long-term biofilm adaptation and instant change of wastewater pH. Mg(OH)₂ dosing rapidly inhibited H₂S at high pH levels and changed microbial community structure after long-term exposure. The transformation of biomarkers was a combined result of pH-driven abiotic process and biodegradation in the dosing-impacted sewers. The high stability of biomarkers like acesulfame and carbamazepine was unaffected by Mg(OH)₂ dosing. Most unstable biomarkers like caffeine, codeine and nicotine presented less degradation and extended half-lives in sewers received either long-term or short-term dosing, compared to their rapid losses under normal sewer conditions. This study provides a comprehensive understanding of both instant and lasting impacts of Mg(OH)₂ dosing on microbial community, biological activity, and biomarker stability in sewers. The longer half-lives of biomarkers in Mg(OH)2-dosed sewers benefited WBE application due to the improved detection reliability and less uncertainty related to biomarker loss, suggesting that chemical dosing information is required for accurate WBE estimation within a catchment.

Could chloroxylenol be used as WBE biomarker in gravity sewers? Fates, behaviors and feasible conditions

Understanding the in-sewer stability of chemical biomarkers is crucial for effective wastewater-based epidemiology (WBE) studying. Sewer conditions, including environmental and biological factors, significantly influence biomarker transformations. This study investigated the stability of chloroxylenol (PCMX) under different levels of pH, temperature, shear force, and ventilation status, and then clarified the fate and behavior of PCMX in gravity sewers (GS). Results indicated the stability of PCMX obviously increased with higher pH and shear force, and lower temperature in both well- and partially-ventilated GS reactors. In poorly-ventilated GS reactors, the highest degradation rates occurred under normal conditions (pH = 7.0, T = 20 °C, shear = 1.15 N/m2). Biological activity (MPR>SPR) and dissolved oxygen (DO) primarily drove PCMX transformation, with minimal effects from pH, temperature, and shear force. A positive correlation existed between PCMX transformation and DO, and a negative correlation existed between PCMX transformation and biological activity. Mass balance analysis indicated that adsorption and bioaccumulation dominated PCMX transformation in GS, while biotransformation occurred with the increasing of DO and prolongation of HRT. Additionally, the suitability of PCMX as a WBE biomarker under different GS conditions was assessed. PCMX was viable as a biomarker in partially-ventilated GS under pH 8 or shears force of 0.48 N/m2 conditions, and in poorly-ventilated GS under pH 6 or shears force of 0.48 N/m2 conditions. This study enhances understanding of factors affecting PCMX stability and supports its application as a WBE biomarker in community health assessments.

A novel data-driven screening method of antidepressants stability in wastewater and the guidance of environmental regulations

Wastewater-based epidemiology (WBE) represents a powerful technique for quantifying the attenuation characteristics and consumption of pharmaceuticals. In addition to WBE, no further methods have been developed to assess the wastewater stability related to antidepressants (ADs). In this study, the biodegradability, solubility, and adsorption or partition of 66 ADs were objectively scored according to the relevant guidelines of the Organisation for Economic Cooperation and Development. An assessment framework and the MSSL-RealFormer classification model of ADs wastewater stability were constructed based on physicochemical properties to predict the ADs wastewater stability and the quantitative structure-activity relationship. The constructed MSSL-RealFormer classification model exhibited a markedly higher prediction accuracy than traditional methods. Furthermore, 15 high-stable ADs in wastewater with low biodegradability, high solubility, and low adsorption or partition were identified. SHapley Additive exPlanation method demonstrated that group hydrophobicity, electrostatic and van der Waals forces exerted a significant influence on the ADs wastewater stability. And molecular stability was found to be significantly correlated with the ADs wastewater stability. A combination of density functional theory and MSSL-RealFormer classification model was employed to identify 17 high-stable transformation products of nine medium- and low-stable ADs in wastewater. The Ecological Structure Activity Relationships model demonstrated that bupropion, tapentadol and chlorpheniramine exhibited significant acute toxicity to the aquatic food chain. In this study, a novel deep learning model was constructed to rapidly screen the correlation between the ADs wastewater stability and their molecular structures. It is anticipated to prove a favorable tool for optimizing the wastewater stability screening of pharmaceuticals.

Recent advances in the removal of psychoactive substances from aquatic environments: A review

Psychoactive substances (PS) have become emerging contaminants in aquatic environments, characterized by their wide distribution, high persistence, bioaccumulation and toxicity. They are difficult to be completely removed in sewage treatment plants due to their high stability under different conditions. The incomplete removal of PS poses a threat to the aquatic animals and can also lead to human health problems through accumulation in the food chain. PS has become a huge burden on global health systems. Therefore, finding an effective technology to completely remove PS has become a "hot topic" for researchers. The methods for removal PS include physical techniques, chemical methods and biological approaches. However, there is still a lack of comprehensive and systematic exploration of these methods. This review aims to address this gap by providing a comprehensive overview of traditional strategies, highlighting recent advancements, and emphasizing the potential of natural aquatic plants in removing trace PS from water environments. Additionally, the degradation mechanisms that occur during the treatment process were discussed and an evaluation of the strengths and weaknesses associated with each method was provided. This work would help researchers in gaining a deeper understanding of the methodologies employed and serve as a reference point for future research endeavors and promoting the sustainable and large-scale application of PS elimination.

Monitoring of ketamine-based emerging contaminants in wastewater: a direct-injection method and fragmentation pathway study

The ketamine (KET) and its analogs consumed by humans are becoming emerging contaminants (ECs), as they at present in surface waters after being carried through wastewater systems. Drugs in wastewater can be analyzed using the direct-injection method, a simple wastewater analysis (WWA) method that can provide objective, continuous and nearly to real-time findings. This article describes an ultra-high-pressure liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous quantification and confirmation of seven KET-based ECs in wastewater by direct injection. After optimization of the UPLC-MS/MS and sample pretreatment conditions, the method was validated and applied to samples (n = 157) collected from several wastewater treatment plants (WWTPs) in southern China in which KET had the highest detection rate. The established direct-injection method was not only simple to perform but also had better sensitivity, shorter detection times, and analyzed more KET-based ECs than currently published methods, meeting the requirements for the monitoring and high-throughput analysis of common KET-based ECs. We also analyzed the fragmentation pathway of KET-based ECs to obtain product ion information on other unknown substances. Additional studies are needed to establish a comprehensive direct-injection screening method of ECs in wastewater on model-based assessment.

Exposure to environmental pollutants: A mini-review on the application of wastewater-based epidemiology approach

Wastewater-based epidemiology (WBE) is considered an innovative and promising tool for estimating community exposure to a wide range of chemical and biological compounds by analyzing wastewater. Despite scholars' interest in WBE studies, there are uncertainties and limitations associated with this approach. This current review focuses on the feasibility of the WBE approach in assessing environmental pollutants, including pesticides, heavy metals, phthalates, bisphenols, and personal care products (PCPs). Limitations and challenges of WBE studies are initially discussed, and then future perspectives, gaps, and recommendations are presented in this review. One of the key limitations of this approach is the selection and identification of appropriate biomarkers in studies. Selecting biomarkers considering the basic requirements of a human exposure biomarker is the most important criterion for validating this new approach. Assessing the stability of biomarkers in wastewater is crucial for reliable comparisons of substance consumption in the population. However, directly analyzing wastewater does not provide a clear picture of biomarker stability. This uncertainty affects the reliability of temporal and spatial comparisons. Various uncertainties also arise from different steps involved in WBE. These uncertainties include sewage sampling, exogenous sources, analytical measurements, back-calculation, and estimation of the population under investigation. Further research is necessary to ensure that measured pollutant levels accurately reflect human excretion. Utilizing data from WBE can support healthcare policy in assessing exposure to environmental pollutants in the general population. Moreover, WBE seems to be a valuable tool for biomarkers that indicate healthy conditions, lifestyle, disease identification, and exposure to pollutants. Although this approach has the potential to serve as a biomonitoring tool in large communities, it is necessary to monitor more metabolites from wastewater to enhance future studies.

Making waves: Wastewater-based surveillance of cannabis use

Monitoring cannabis consumption holds great interest due to the increasing trend towards its legalization for both medicinal and recreational purposes, despite the potential risks and harms involved. Wastewater-based surveillance (WBS) offers a valuable tool for assessing shifts and patterns in drug consumption and to evaluate law enforcement strategies and harm reduction programs. However, WBS-derived cannabis use estimates have been linked to greater uncertainties compared to other drugs, in part due to the many different routes of administration and a substantial excretion of metabolites in faecal matter. Therefore, the usual approach for estimating consumed amounts and scaling consumption compared to other problem drugs requires a rethink. This viewpoint highlights the progress made in this area and describes the current existing barriers related to in-sewer and in-sample behaviour (e.g., adsorption/desorption mechanisms), analytical procedures used (e.g., sample preparation), and pharmacokinetic aspects (e.g., administration route) linked to cannabis biomarkers in influent wastewater. These need to be addressed to improve the estimation of cannabis use and reflect spatial and temporal trends in the same way as for other drugs. Until then, we recommend being cautious when interpreting wastewater-based cannabis consumption estimates.

Do the lockdown-imposed changes in a wastewater treatment plant catchment's socio-demographics impact longitudinal temporal trends in psychoactive pharmaceutical use?

Wastewater-based epidemiology (WBE) includes the analysis of human metabolic biomarkers of xenobiotics in influent wastewater. WBE complements existing drug utilization approaches and provides objective, spatio-temporal information on the consumption of pharmaceuticals in the general population. This approach was applied to 24-h composite influent wastewater samples from Leuven, Belgium. Daily samples were analysed from September 2019 to December 2019 (n = 76), and on three days of the week (Monday, Wednesday, Saturday) from January 2020 to April 2022 (n = 367). Sample analysis consisted of 96-well solid-phase extraction and liquid chromatography coupled to tandem mass spectrometry. Measured concentrations of 21 biomarkers for antidepressant and opioid use were converted to population-normalized mass loads (PNML) by considering the flow rate and catchment population. To capture population movements, mobile phone data was used. Amitriptyline, hydroxy-bupropion, norcitalopram, citalopram, normirtazapine, trazodone, O-desmethylvenlafaxine, codeine, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), methadone, morphine, O-desmethyltramadol, and tramadol were included in the temporal assessment since concentrations were above the lower limit of quantification. The PNML of most biomarkers increased (with 3-119 %) throughout the sampling period. The population disruption during the COVID-19 pandemic led to a major change in the socio-demographics of the catchment area, resulting in temporal differences in the PNML of the different biomarkers. As such, higher PNML were observed during the different lockdown phases, which were characterized by the outflow of university students and a decreasing commuting in and out the catchment area. The effects of the fluctuating socio-demographics of the catchment population were further evidenced by the different week-weekend pattern of PNMLs over the course of the sampling campaign. Mean parent/metabolite ratios (i.e., citalopram/norcitalopram, tramadol/O-desmethyltramadol, venlafaxine/O-desmethylvenlafaxine, and methadone/EDDP) remained relatively stable throughout the entire sampling campaign (RSD% below 25 % for all ratios, except for methadone/EDDP) and therefore were not affected by this population change.

Antibiotic resistomes in face-mask biofilm along an urban river: Multiple drivers and co-occurrence with human opportunistic pathogens

Discarded face masks from the global COVID-19 pandemic have contributed significantly to plastic pollution in surface water, whereas their potential as a reservoir for aquatic pollutants is not well understood. Herein, we conducted a field experiment along a human-impacted urban river, investigating the variations of antibiotic resistance genes (ARGs), pathogens, and water-borne contaminants in commonly-used face masks. Results showed that high-biomass biofilms formed on face masks selectively enriched more ARGs than stone biofilm (0.08-0.22 vs 0.07-0.15 copies/16 S rRNA gene copies) from bulk water, which mainly due to unique microbial communities, enhanced horizontal gene transfer, and selective pressure of accumulated contaminants based on redundancy analysis and variation partitioning analysis. Several human opportunistic pathogens (e.g., Acinetobacter, Escherichia-Shigella, Bacillus, and Klebsiella), which are considered potential ARG carriers, were also greatly concentrated in face-mask biofilms, imposing a potential threat to aquatic ecological environment and human health. Moreover, wastewater treatment plant effluents, as an important source of pollutants to urban rivers, further aggravated the abundances of ARGs and opportunistic pathogens in face-mask biofilms. Our findings demonstrated that discarded face masks provide a hotspot for the proliferation and spread of ARGs and pathogens in urban water, highlighting the urgent requirement for implementing stricter regulations in face mask disposal.

Effects of sewer biofilms on the degradability of carbapenems in wastewater using laboratory scale bioreactors

Carbapenems are last-resort antibiotics used to treat bacterial infections unsuccessfully treated by most common categories of antibiotics in humans. Most of their dosage is secreted unchanged as waste, thereby making its way into the urban water system. There are two major knowledge gaps addressed in this study to gain a better understanding of the effects of their residual concentrations on the environment and environmental microbiome: development of a UHPLC-MS/MS method of detection and quantification from raw domestic wastewater via direct injection and study of their stability in sewer environment during the transportation from domestic sewers to wastewater treatment plants. The UHPLC-MS/MS method was developed for four carbapenems: meropenem, doripenem, biapenem and ertapenem, and validation was performed in the range of 0.5-10 μg/L for all analytes, with limit of detection (LOD) and limit of quantification (LOQ) values ranging from 0.2-0.5 μg/L and 0.8-1.6 μg/L respectively. Laboratory scale rising main (RM) and gravity sewer (GS) bioreactors were employed to culture mature biofilms with real wastewater as the feed. Batch tests were conducted in RM and GS sewer bioreactors fed with carbapenem-spiked wastewater to evaluate the stability of carbapenems and compared against those in a control reactor (CTL) without sewer biofilms, over a duration of 12 h. Significantly higher degradation was observed for all carbapenems in RM and GS reactors (60 - 80%) as opposed to CTL reactor (5 - 15%), which indicates that sewer biofilms play a significant role in the degradation. First order kinetics model was applied to the concentration data along with Friedman's test and Dunn's multiple comparisons analysis to establish degradation patterns and differences in the degradation observed in sewer reactors. As per Friedman's test, there was a statistically significant difference in the degradation of carbapenems observed depending on the reactor type (p = 0.0017 - 0.0289). The results from Dunn's test indicate that the degradation in the CTL reactor was statistically different from that observed in either RM (p = 0.0033 - 0.1088) or GS (p = 0.0162 - 0.1088), with the latter two showing insignificant difference in the degradation rates observed (p = 0.2850 - 0.5930). The findings contribute to the understanding about the fate of carbapenems in urban wastewater and the potential application of wastewater-based epidemiology.

Biomarker selection strategies based on compound stability in wastewater-based epidemiology

The specific compositions of human excreta in sewage can be used as biomarkers to indicate the disease prevalence, health status, and lifestyle of the population living in the investigated catchment. It is important for guiding and evaluating public health policies as well as promoting human health development. Among several parameters of wastewater-based epidemiology (WBE), the decay of biomarkers during transportation in sewer and storage plays a crucial role in the back-calculation of population consumption. In this paper, we summarized the stability data of common biomarkers in storage at different temperatures and in-sewer transportation. Among them, cardiovascular drugs and antidiabetic drugs are very stable which can be used as biomarkers; most of the illicit drugs are stable except for cocaine, heroin, and tetrahydrocannabinol which could be substituted by their metabolites as biomarkers. There are some losses for part of antibiotics and antidepressants even in frozen storage. Rapid detection of contagious viruses is a new challenge for infectious disease control. With the deeper and broader study of biomarkers, it is expected that the reliable application of the WBE will be a useful addition to epidemiological studies.

A critical review of wastewater quality variation and in-sewer processes during conveyance in sewer systems

In-sewer physio-biochemical processes cause significant variations of wastewater quality during conveyance, which affects the influent to a wastewater treatment plant (WWTP) and arguably the microbial community of biological treatment units in a WWTP. In wet weather, contaminants stored in sewer deposits can be resuspended and migrate downstream or be released during combined sewer overflows to the urban water bodies, posing challenges to the treatment facilities or endangering urban water quality. Therefore, in-sewer transformation and migration of contaminants have been extensively studied. The compiled results from representative research in the past few decades showed that biochemical reactions are both cross-sectionally and longitudinally organized in the deposits and the sewage, following the redox potential as well as the sequence of macromolecule/contaminant degradation. The sewage organic contents and sewer biofilm microorganisms were found to covary but more systematic studies are required to examine the temporal stability of the feature. Besides, unique communities can be developed in the sewage phase. The enrichment of the major sewage-associated microorganisms can be explained by the availability of biodegradable organic contents in sewers. The sewer deposits, including biofilms, harbor both microorganisms and contaminants and usually can provide longer residence time for in-sewer transformation than wastewater. However, the interrelationships among contaminant transformation, microorganisms in the deposits/biofilms, and those in the sewage are largely unclear. Specifically, the formation and migration of FOG (fat, oil, and grease) deposits, generation and transport of contaminants in the sewer atmosphere (e.g., H₂S, CH₄, volatile organic compounds, bioaerosols), transport and transformation of nonconventional contaminants, such as pharmaceuticals and personal care products, and wastewater quality variation during the biofilm rehabilitation period after damages caused by rains/storms are some topics for future research. Moreover, systematic and standardized field analysis of real sewers under dynamic wastewater discharge conditions is necessary. We believe that an improved understanding of these processes would assist in sewer management and better prepare us for the challenges brought about by climate change and water shortage.

The role of the sewer system in estimating urban emissions of chemicals of emerging concern

The use of chemicals by society has resulted in calls for more effective control of their emissions. Many of these chemicals are poorly characterized because of lacking data on their use, environmental fate and toxicity, as well as lacking detection techniques. These compounds are sometimes referred to as contaminants of emerging concern (CECs). Urban areas are an important source of CECs, where these are typically first collected in sewer systems and then discharged into the environment after being treated in a wastewater treatment plant. A combination of emission estimation techniques and environmental fate models can support the early identification and management of CEC-related environmental problems. However, scientific insight in the processes driving the fate of CECs in sewer systems is limited and scattered. Biotransformation, sorption and ion-trapping can decrease CEC loads, whereas enzymatic deconjugation of conjugated metabolites can increase CEC loads as metabolites are back-transformed into their parent respective compounds. These fate processes need to be considered when estimating CEC emissions. This literature review collates the fragmented knowledge and data on in-sewer fate of CECs to develop practical guidelines for water managers on how to deal with in-sewer fate of CECs and highlights future research needs. It was assessed to what extent empirical data is in-line with text-book knowledge and integrated sewer modelling approaches. Experimental half-lives (n = 277) of 96 organic CECs were collected from literature. The findings of this literature review can be used to support environmental modelling efforts and to optimize monitoring campaigns, including field studies in the context of wastewater-based epidemiology.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11157-022-09638-9.

Fate characteristics, exposure risk, and control strategy of typical antibiotics in Chinese sewerage system: A review

In China, the sewerage system plays an essential role in antibiotic removal; however, the fate profiles of antibiotics in sewers are not well understood, and risk identification throughout the sewerage system is inadequate. Based on the extensive detection results for typical groups of antibiotics in the discharge sources, influent and effluent from wastewater treatment plants (WWTPs), and excess sludge, a comprehensive evaluation was conducted to reveal the elimination profiles of the antibiotics, identify the fate characteristics in both sewers and WWTPs, assess the exposure risk levels, and propose a control strategy. The total concentration (based on the median concentrations of the target antibiotics) in aqueous waters was estimated to decrease from 7383.4 ng/L at the discharge source to 886.6 ng/L in the WWTP effluent, among which 69.6% was reduced by sewers and 18.4% was reduced by WWTPs. Antibiotic reduction in sewers was a combined effect of dilution, physiochemical reactions, sorption, biodegradation, and retransformation, and the A2O-MBR + ozonation process in the WWTPs exhibited superior performance in diminishing antibiotics. Notably, accumulated antibiotics in the excess sludge posed a high risk to natural environments (with a risk quotient of approximately 13.0), and the potential risk during combined sewer overflows (CSOs) was undetermined. Thus, enhanced sludge treatment techniques, accurate risk prediction, and proper precautions at CSOs are required to mitigate potential risk. A novel scheme involving an accurate estimation of discharge loads, preliminary treatment of highly concentrated discharge sources, and synergic control in sewers was proposed to eliminate antibiotics at the front end of pipes.

Analytical investigation of cannabis biomarkers in raw urban wastewater to refine consumption estimates

Wastewater analysis of Δ⁹-tetrahydrocannabinol (THC) biomarkers can provide essential information on trends in cannabis consumption. Although analysis is mostly focused on the aqueous phase, previous studies have illustrated the need of improving the measurements of raw influent wastewater (IWW) considering also suspended solids. This is important for cannabis biomarkers, because a substantial part of them is expected to be found in the suspended solids due to their more lipophilic character compared with other metabolites/drugs included in these types of studies. However, it remains open to which extent trend estimates might be affected by solely analysing the liquid phase. To investigate this aspect, robust analytical methodologies are required to measure both the liquid and solid phases of IWW. In this work, we firstly tested liquid-liquid extraction (LLE) for THC and its major metabolites (THCOH, and THCCOOH). Using LLE, no filtration or centrifugation step was required for raw IWW analysis, and the three analytes were extracted from both the liquid and the solid phase simultaneously. In parallel, the raw IWW was centrifuged and the obtained solid and liquid phases were analyzed separately: the liquid phase by both LLE and solid phase extraction (SPE) for comparison of data, and the suspended solids by solid-liquid extraction (SLE). The separate analysis of both phases in a number of samples revealed that a significant amount of cannabis biomarkers (ranging from 42 to 90%) was found in the suspended solids. In addition, the total amount of cannabis biomarkers obtained by analysing raw IWW on the one hand, and by separate analysis of the liquid and the solid phases, on the other hand, was in good agreement. Data from this study show that the sole analysis of the liquid phase would lead to a notable underestimation of cannabis biomarkers concentrations in IWW.

Effects of sewer biofilm on the degradation of drugs in sewage: A microcosm study

A thorough understanding of the in-sewer stability of chemical biomarkers is critical in applying wastewater-based surveillance of community drug use. In this study, we examined the effects of sewer biofilm on the degradation of commonly abused drugs, namely, morphine, fentanyl, cocaine, and amphetamine, in wastewater using 48-h batch degradation tests. The experiments were designed to distinguish among abiotic, biochemical, and physical degradation processes, and used mature biofilm obtained from an actual sewer line. Parallel microcosm tests were conducted using wastewater with and without suspended biofilm. Results indicate that first order kinetics describe the degradation of the drugs in both wastewater and wastewater-biofilm microcosms. Amphetamine was most stable in all microcosms, with a maximum removal of only 34% after 48 h. Abiotic chemical transformation played a major role in the degradation of morphine (k_ab = 0.018 h^-1), fentanyl (k_ab = 0.022 h^-1) and cocaine (k_ab = 0.049 h^-1) in wastewater. Fentanyl removal from wastewater was also influenced by the presence of biofilm (k_f = 0.015 h^-1). This study is the first to report on the effect of sewer biofilm on fentanyl degradation, and highlights the need to account for in-sewer drug stability in wastewater-based drug use estimation, particularly for chemicals with high affinity for organics.

Current and future perspectives for wastewater-based epidemiology as a monitoring tool for pharmaceutical use

The medical and societal consequences of the misuse of pharmaceuticals clearly justify the need for comprehensive drug utilization research (DUR). Wastewater-based epidemiology (WBE) employs the analysis of human metabolic excretion products in wastewater to monitor consumption patterns of xenobiotics at the population level. Recently, WBE has demonstrated its potential to evaluate lifestyle factors such as illicit drug, alcohol and tobacco consumption at the population level, in near real-time and with high spatial and temporal resolution. Up until now there have been fewer WBE studies investigating health biomarkers such as pharmaceuticals. WBE publications monitoring the consumption of pharmaceuticals were systematically reviewed from three databases (PubMed, Web of Science and Google Scholar). 64 publications that reported population-normalised mass loads or defined daily doses of pharmaceuticals were selected. We document that WBE could be employed as a complementary information source for DUR. Interest in using WBE approaches for monitoring pharmaceutical use is growing but more foundation research (e.g. compound-specific uncertainties) is required to link WBE data to routine pharmacoepidemiologic information sources and workflows. WBE offers the possibility of i) estimating consumption of pharmaceuticals through the analysis of human metabolic excretion products in wastewater; ii) monitoring spatial and temporal consumption patterns of pharmaceuticals continuously and in near real-time; and iii) triangulating data with other DUR information sources to assess the impacts of strategies or interventions to reduce inappropriate use of pharmaceuticals.

In-sewer stability of selected analgesics and their metabolites

Understanding the in-sewer stability of analgesic biomarkers is important for interpreting wastewater-based epidemiology (WBE) data to estimate community-wide analgesic drugs consumption. The in-sewer stability of a suite of 19 analgesics and their metabolites was assessed using lab-scale sewer reactors. Target biomarkers were spiked into wastewater circulating in simulated gravity, rising main and control (no biofilm) sewer reactors. In-sewer transformation was observed over a hydraulic retention time of 12 h. All investigated biomarkers were stable under control reactor conditions. In gravity sewer conditions, diclofenac, desmetramadol, ibuprofen carboxylic acid, ketoprofen, lidocaine and tapentadol were highly stable (0-20% transformation in 12 h). Valdecoxib, parecoxib, etoricoxib, indomethacin, naltrexone, naloxone, piroxicam, ketoprofen, lidocaine, tapentadol, oxymorphone, hydrocodone, meperidine, hydromorphone were considered as moderately stable biomarkers (20-50% transformation in 12 h). Celecoxib and sulindac were considered unstable biomarkers (>50% transformation in 12 h). Ketoprofen, lidocaine, tapentadol, meperidine, hydromorphone were transformed to 0-20% whereas diclofenac, desmetramadol, ibuprofen carboxylic acid, valdecoxib, parecoxib, etoricoxib, indomethacin, naltrexone, piroxicam were transformed up to 20-50% in 12 h in rising main reactor (RMR). These biomarkers were considered as highly stable and stable biomarkers in RMR, respectively. Sulindac, celecoxib, naloxone, oxymorphone and hydrocodone were transformed more than 50% in 12 h and considered as unstable biomarkers in RMR. This study provides the information for a better understanding of the in-sewer loss of the analgesics before using them in WBE biomarkers for estimating drug loads at the population level.

Water quality modeling in sewer networks: Review and future research directions

Urban sewer networks (SNs) are increasingly facing water quality issues as a result of many challenges, such as population growth, urbanization and climate change. A promising way to addressing these issues is by developing and using water quality models. Many of these models have been developed in recent years to facilitate the management of SNs. Given the proliferation of different water quality models and the promise they have shown, it is timely to assess the state-of-the-art in this field, to identify potential challenges and suggest future research directions. In this review, model types, modeled quality parameters, modeling purpose, data availability, type of case studies and model performance evaluation are critically analyzed and discussed based on a review of 110 papers published between 2010 and 2019. The review identified that applications of empirical and kinetic models dominate those of data-driven models for addressing water quality issues. The majority of models are developed for prediction and process understanding using experimental or field sampled data. While many models have been applied to real problems, the corresponding prediction accuracies are overall moderate or, in some cases, low, especially when dealing with larger SNs. The review also identified the most common issues associated with water quality modeling of SNs and based on these proposed several future research directions. These include the identification of appropriate data resolutions for the development of different SN models, the need and opportunity to develop hybrid SN models and the improvement of SN model transferability.

Application of wastewater-based epidemiology to investigate stimulant drug, alcohol and tobacco use in Lithuanian communities

WBE was applied to evaluate illicit drug (i.e. amphetamine, cocaine, MDMA and methamphetamine), alcohol and tobacco use in three Lithuanian cities in 2018 and 2019. Considerable concentrations of methamphetamine and MDMA were found in the three locations, suggesting a specific Lithuanian consumption pattern. Yet, unexpected high concentrations of amphetamine (>4 μg/L) were detected in two samples of Kaunas in 2018. Through the use of chiral analysis and non-target and suspect drug precursor compound screening, these extreme values were confirmed to be the result of direct disposal of amphetamine in the sewers. Furthermore, substantial alcohol use was measured in the three investigated catchment populations of Lithuania with almost 4 standard drinks/day/inhabitant aged 15+ on average in 2019. For tobacco, an average of 5.6 cigarettes/day/inhabitant aged 15+ in 2019 was reported with large discrepancies between WBE figures and sales data, potentially highlighting illegal trade of tobacco products.

Effects of pH, Temperature, Suspended Solids, and Biological Activity on Transformation of Illicit Drug and Pharmaceutical Biomarkers in Sewers

In-sewer stability of biomarkers is a critical factor for wastewater-based epidemiology, as it could affect the accuracy of the estimated prevalence of substances in the community. The spatiotemporal variations of environmental and biological conditions in sewers can influence the transformation of biomarkers. To date, the relationship between environmental variables and biomarker stability in sewers is poorly understood. Therefore, this study evaluated the transformation of common illicit drug and pharmaceutical biomarkers in laboratory sewer reactors with different levels of pH, temperature, and suspended solids. The correlations between degradation rates of 14 biomarkers, 3 controlled environmental variables (pH, temperature, and suspended solids concentration), and 3 biological activity indicators (sulfide production rate, methane production rate, and the removal rate of soluble chemical oxygen demand (SCOD)) were assessed using correlation matrix, stepwise regression method, and principal component analysis. The consistent results affirmed the dominant effects of biological activities and pH on biomarker transformation in sewers, particularly for labile compounds, whereas the impact of temperature or suspended solids was less significant. This study enhances the understanding of factors affecting the fate of micropollutants in sewer systems and facilitates the interpretation of WBE results for assessing drug use and public health in communities.

Using Prescription and Wastewater Data to Estimate the Correction Factors of Atenolol, Carbamazepine, and Naproxen for Wastewater-Based Epidemiology Applications

The correction factor (CF) is a critical parameter in wastewater-based epidemiology (WBE) that significantly influences the accuracy of the final consumption estimates. However, most CFs have been derived from a few old pharmacokinetic studies and should be re-evaluated and refined to improve the accuracy of the WBE approach. This study aimed to review and estimate the CFs for atenolol, carbamazepine, and naproxen for WBE using the daily mass loads of those pharmaceuticals in wastewater and their corresponding dispensed prescription data in Australia. Influent wastewater samples were collected from wastewater treatment plants serving approximately 24% of the Australian population and annual national dispensed prescription data. The estimated CFs for atenolol and carbamazepine are 1.37 (95% CI: 1.17-1.66) and 8.69 (95% CI: 7.66-10.03), respectively. Due to significant over-the-counter sales of naproxen, a reliable CF could not be estimated based on prescription statistics. Using an independent dataset of 186 and 149 wastewater samples collected in an urban catchment in 2011 and 2012, WBE results calculated using the new CFs matched well with the dispensed data for atenolol and carbamazepine in the catchment area.

Systematic Evaluation of the In-Sample Stability of Selected Pharmaceuticals, Illicit Drugs, and Their Metabolites in Wastewater

The in-sample stability of selected pharmaceuticals, illicit drugs, and their metabolites in wastewater was assessed under six different conditions-untreated, addition of hydrochloric acid or sodium metabisulfite solution, combined with or without sterile filtration, and at four representative temperatures, at 35 °C for up to 28 days, 22 °C for 56 days, and 4 °C and -20 °C for 196 days, or freeze/thaw cycles for 24 weeks. Paracetamol, 6-monoacetylmorphine, morphine, and cocaine were poorly stable in untreated wastewater-e.g., with 50% transformation within 1.2-8.1 days at 22 °C, and acidification reduced their in-sample transformations. Acesulfame, carbamazepine, cotinine, methamphetamine, 3,4-methylenedioxy-methamphetamine (MDMA), ketamine, norfentanyl, 3,4-methylenedioxy-N-ethylamphetamine (MDEA), and norbuprenorphine were highly or moderately stable over the observed period, even in untreated wastewater. Fitting of pseudo-first-order kinetics and the Arrhenius equation was used to develop a multistage transformation estimation model combined with an interactive tool to evaluate possible transformation scenarios of selected biomarkers for the processes from sampling to preanalysis. However, as the wastewater composition can vary between sites and over time, the variability of in-sample stability requires further exploration.

Transformation of Illicit Drugs and Pharmaceuticals in Sewer Sediments

In-sewer stability of human excreted biomarkers is a critical factor of wastewater-based epidemiology in back-estimating illicit drug and pharmaceutical use in the community. Biomarker stability has been investigated in sewers with the presence of biofilms, but the understanding in sewer sediments is still lacking. This study for the first time employed a laboratory sediment reactor to measure 18 illicit drug and pharmaceutical biomarkers under gravity sewer environments with the presence of sediments. Biomarkers exhibited various stability patterns due to transformation processes occurring in the bulk wastewater and sediments. The attenuation of a biomarker by sediments is driven by complex processes involving biodegradation, diffusion, and sorption, which is directly proportional to the ratio of sediment surface area against wastewater volume. The sediment-driven transformation coefficients of biomarkers are higher than the accordingly biofilm-mediated rates because of stronger microbial activities in sediments. Additionally, the stability of most biomarkers was insensitive to the natural pH variation in sewers, except for a few compounds (e.g., methadone, ketamine, and paracetamol) susceptible to pH changes. In general, this study delineates the stability data of various biomarkers in gravity sewers with sediments, which are novel and long-missing information for wastewater-based epidemiology and improve the reliability of back-estimation in complex sewer networks.

Do food and stress biomarkers work for wastewater-based epidemiology? A critical evaluation

Dietary characteristics and oxidative stress are closely linked to the wellbeing of individuals. In recent years, various urinary biomarkers of food and oxidative stress have been proposed for use in wastewater-based epidemiology (WBE), in efforts to objectively monitor the food consumed and the oxidative stress experienced by individuals in a wastewater catchment. However, it is not clear whether such biomarkers are suitable for wastewater-based epidemiology. This study presents a suite of 30 urinary food and oxidative stress biomarkers and evaluates their applicability for WBE studies. This includes 22 biomarkers which were not previously considered for WBE studies. Daily per capita loads of biomarkers were measured from 57 wastewater influent samples from nine Australian catchments. Stability of biomarkers were assessed using laboratory scale sewer reactors. Biomarkers of consumption of vitamin B2, vitamin B3 and fibre, as well as a component of citrus had per capita loads in line with reported literature values despite susceptibility of degradation in sewer reactors. Consumption biomarkers of red meat, fish, fruit, other vitamins and biomarkers of stress had per capita values inconsistent with literature findings, and/or degraded rapidly in sewer reactors, indicating that they are unsuitable for use as WBE biomarkers in the traditional quantitative sense. This study serves to communicate the suitability of food and oxidative stress biomarkers for future WBE research.

Coupling electrochemical ammonia extraction and cultivation of methane oxidizing bacteria for production of microbial protein

Conventional treatment of residual resources relies on nutrient removal to limit pollution. Recently, nutrient recovery technologies have been proposed as more environmentally and energetically efficient strategies. Nevertheless, the upcycling of recovered resources is typically limited by their quality or purity. Specifically, nitrogen extracted from residual streams, such as anaerobic digestion (AD) effluents and wastewaters, could support microbial protein production. In this context, this study was performed as a proof-of-concept to combine nitrogen recovery via electrochemical reactors with the production of high quality microbial protein via cultivation of methanotrophs. Two types of AD effluents, i.e., cattle manure and organic fraction of municipal solid waste, and urine were tested to investigate the nitrogen extraction efficiency. The results showed that 31-51% of the nitrogen could be recovered free of trace chemicals from residual streams depending on the substrate and voltage used. Based on the results achieved, higher nitrogen concentration in the residual streams resulted in higher nitrogen flux between anodic and cathodic chambers. Results showed that the extraction process has an energy demand of 9.97 (±0.7) - 14.44 (±1.19) kWh/kg-N, depending on the substrate and operating conditions. Furthermore, a mixed-culture of methanotrophic bacteria could grow well with the extracted nitrogen producing a total dry weight of 0.49 ± 0.01 g/L. Produced biomass contained a wide range of essential amino acids making it comparable with conventional protein sources.

Considerations for assessing stability of wastewater-based epidemiology biomarkers using biofilm-free and sewer reactor tests

Wastewater-based epidemiology is an increasingly popular method for analysing drugs or metabolites excreted by populations. The in-sewer transformation of biomarkers is important but often receives little consideration in published studies. Many studies publish stability under biofilm-free conditions only, which do not represent actual sewer conditions. This study aims to fill a gap in the field by comparing the wastewater stability of 33 licit drug and pharmaceutical biomarkers in biofilm-free (BFF) conditions to stability in sewer biofilm reactors. All but one biomarker was stable under BFF conditions, whereas most transformed in sewer biofilm reactors. Sewer reactor results tended to overestimate the degradation in pilot and actual sewers, whereas BFF stability had no clear relationship to stability in pilot and actual sewers. Our results provide additional basis for more informed interpretation of biofilm-free and sewer reactor stability results for past and future WBE studies.

Development and application of the analytical method for illicit drugs and metabolites in fish tissues

In this study, we developed a screening method for highly accurate and sensitive analysis of 12 illicit drugs and metabolites in fish tissues. The approach was based on ultrasonic-assisted extraction and solid phase extraction, followed by ultra-performance liquid chromatography-tandem mass spectrometry analysis. The homogenized samples were ultrasonic-assisted extracted with 1% acetic acid in methanol followed by SPE cleanup with Oasis MCX cartridge. The method was validated in accordance with the European Medicines Agency guidelines by evaluating the following required parameters: the limits of detection and limits of quantification, linearity, accuracy, repeatability, recovery of extraction, and matrix effect. For the tissues involved in this study, the recoveries ranged from 60% to 127%, and the matrix effect ranged from -19% to 83% with the inter- and intra-day variability below 12%. The method has been successfully applied to wild fish caught from six sampling sites of four urban rivers in Beijing, China. The analysis showed that the target compounds, including amphetamine, 3,4-methylenedioxyamphetamine, codeine and heroin were detected with high detection frequencies. Codeine exhibited the highest bioaccumulation factor (up to 73,986) in the muscle of Crucian carp, while ketamine tended to accumulate in the skin, 3,4-methylenedioxyamphetamine and heroin tended to accumulate in gastrointestinal tract, respectively.

Modelling micropollutant fate in sewer systems - A new systematic approach to support conceptual model construction based on in-sewer hydraulic retention time

Conceptual sewer models are useful tools to assess the fate of micropollutants (MPs) in integrated wastewater systems. However, the definition of their model structure is highly subjective, and obtaining a realistic simulation of the in-sewer hydraulic retention time (HRT) is a major challenge without detailed hydrodynamic information or with limited measurements from the sewer network. This study presents an objective approach for defining the structure of conceptual sewer models in view of modelling MP fate in large urban catchments. The proposed approach relies on GIS-based information and a Gaussian mixture model to identify the model optimal structure, providing a multi-catchment conceptual model that accounts for HRT variability across urban catchment. This approach was tested in a catchment located in a highly urbanized Italian city and it was compared against a traditional single-catchment conceptual model (using a single average HRT) for the fate assessment of reactive MPs. Results showed that the multi-catchment model allows for a successful simulation of dry weather flow patterns and for an improved simulation of MP fate compared to the classical single-catchment model. Specifically, results suggested that a multi-catchment model should be preferred for (i) degradable MPs with half-life lower than the average HRT of the catchment and (ii) MPs undergoing formation from other compounds (e.g. human metabolites); or (iii) assessing MP loads entering the wastewater treatment plant from point sources, depending on their location in the catchment. Overall, the proposed approach is expected to ease the building of conceptual sewer models, allowing to properly account for HRT distribution and consequently improving MP fate estimation.

Evaluating the in-sewer stability of three potential population biomarkers for application in wastewater-based epidemiology

Endogenous chemicals specific to human metabolism have been suggested to be good candidates for markers of population size in wastewater-based epidemiology (WBE). So far, creatinine is the only endogenous chemical to be assessed against the criteria of in-sewer stability. This study thus aimed to evaluate the fate of three other endogenous compounds, 5-hydroxy indole acetic acid (5-HIAA), cortisol and androstenedione, under different sewer conditions using laboratory-scale sewer reactors. The results showed that while all compounds were stable in wastewater only (i.e. without biofilm), cortisol and androstenedione degraded quickly in sewers with the presence of sewer biofilms. The degradation followed first-order kinetics similar to that of creatinine. In contrast, 5-HIAA was relatively stable in sewer reactors. This study also recognised the impact of wastewater pH on the detectability of 5-HIAA using a LC-MS/MS direct injection method. In samples acidified to pH 2, the method did not allow routine detection/quantification of 5-HIAA whereas in non-acidified samples the method was sufficiently sensitive for routine quantification of 5-HIAA. The stability of 5-HIAA in sewers and the possibility to measure it using a simple and rapid analytical method corroborate that 5-HIAA may be a suitable biomarker for estimation of population size in WBE.

Non-negligible greenhouse gases from urban sewer system

BACKGROUND

The urban sewer system is an important component of urban water infrastructure for sewage collection and transportation, and in-sewer transportation of sewage can cause multitudinous contaminant degradations which lead to formation of gaseous products. Although the greenhouse gases of methane and carbon dioxide have been confirmed to consist in the gaseous products, the mechanisms of greenhouse gas generation were unclear and the significances of greenhouse gases emission from sewers were generally underestimated.

RESULTS

In this study, 3 years of monitoring was conducted to evaluate the greenhouse gases emission in 37-km-long urban sewer systems covering 13 km². The results showed that the emission of carbon dioxide and methane was extensively existing in sewers, and especially, exhibited a characteristic of regional difference. In order to reveal the formation mechanism of carbon dioxide and methane in sewers, the metagenomic approach was utilized to analyze the annotated pathways and homologous bio-enzymes, and it indicated that fourteen pivotal annotated pathways were involved in the carbon dioxide and methane generation. According to the metagenomics and 3-year monitoring results, the total amounts of carbon dioxide and methane emission in sewers were calculated by the transformation venation of contaminants (such as methyl alcohol, methylamine and acetic acid along branch sewer, sub-main sewer and main sewer, respectively). The calculation results showed that the total greenhouse gas emissions in sewer were calculated to be 199 t/day in Xi'an, and if scaling up as population proportion, the greenhouse gas emission from sewer systems in China could be 30,685 t/day. Comparing with the greenhouse gas emissions from different metropolises (New York City, London and Tokyo) and industries (dairy farms, automobile production and steel enterprises), the amount of greenhouse gases produced by the urban sewer system is much higher.

CONCLUSIONS

This study revealed the transformation pathways of contaminants which promoted the generation of greenhouse gases in sewers. Based on this analysis, the greenhouse gas emissions along sewer systems were calculated. The results indicate that the greenhouse gas emission from sewer systems is non-negligible, and should be attracted sufficient attention.

Experimental Investigation and Modeling of the Transformation of Illicit Drugs in a Pilot-Scale Sewer System

In-sewer stability of illicit drug biomarkers has been evaluated by several reactor-based studies, but less has been done in sewer pipes. Experiments conducted in sewer pipes have advantages over lab-scale reactors in providing more realistic biomarker stability due to the flow and biological dynamics. This study assessed the transportation and transformation of seven illicit drug biomarker compounds in a pilot-scale rising main and a gravity sewer pipe. Biomarkers presented diverse stability patterns in the pilot sewers, based on which a drug transformation model was calibrated. This model was subsequently validated using transformation data sets from the literature, aiming to demonstrate the predictability of the pilot-based transformation coefficients under varying sewer conditions. Furthermore, transformation coefficients for five investigated biomarkers were generated from four studies, and their prediction capabilities under the pilot-sewer conditions were jointly assessed using performance statistics. The transformation model was successful in simulating the in-sewer stability for most illicit drugs. However, further study is required to delineate the sources and pathways for those compounds with potential formations to be simulated in the transformation model. Overall, the transformation model calibrated using the pilot-sewer data is a credible tool for the application of wastewater-based epidemiology.

Systematic evaluation of biomarker stability in pilot scale sewer pipes

Transformation of biomarkers (or their stability) during sewer transport is an important issue for wastewater-based epidemiology (WBE). Most studies so far have been conducted in the laboratory, which usually employed unrealistic conditions. In the present study, we utilized a pilot sewer system including a gravity pipe and a rising main pipe to investigate the fate of 24 pharmaceutical biomarkers. A programmable logic controller was used to control and monitor the system including sewer operational conditions and wastewater properties. Sequential samples were collected that can represent hydraulic retention time (HRT) of up to 8 h in a rising main and 4 h in a gravity sewer. Wastewater parameters and biomarker concentrations were analysed to evaluate the stability and transformation kinetics. The wastewater parameters of the pilot system were close to the conditions of real sewers. The findings of biomarker transformation were also close to real sewer data with seventeen biomarkers reported as stable while buprenorphine, caffeine, ethyl-sulfate, methadone, paracetamol, paraxanthine and salicylic acid degraded to variable extents. Both zero-order and first-order kinetics were used to model the degradation of unstable biomarkers and interestingly the goodness of fit R² for the zero-order model was higher than the first-order model for all unstable biomarkers in the rising main. The pilot sewer system simulates more realistic conditions than benchtop laboratory setups and may provide a more accurate approach for assessing the in-sewer transformation kinetics and stability of biomarkers.

Investigating in-sewer transformation products formed from synthetic cathinones and phenethylamines using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry

Recent studies have demonstrated the role of biofilms on the stability of drug residues in wastewater. These factors are pertinent in wastewater-based epidemiology (WBE) when estimating community-level drug use. However, there is scarce information on the biotransformation of drug residues in the presence of biofilms and the potential use of transformation products (TPs) as biomarkers in WBE. The purpose of this work was to investigate the formation of TPs in sewage reactors in the presence of biofilm mimicking conditions during in-sewer transport. Synthetic cathinones (methylenedioxypyrovalerone, methylone, mephedrone) and phenethylamines (4-methoxy-methamphetamine and 4-methoxyamphetamine) were incubated in individual reactors over a 24h period. Analysis of parent species and TPs was carried out using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QToFMS). Identification of TPs was done using suspect and non-target workflows. In total, 18 TPs were detected and identified with reduction of β-keto group, demethylenation, demethylation, and hydroxylation reactions observed for the synthetic cathinones. For the phenethylamines, N- and O-demethylation reactions were identified. Overall, the experiments showed varying stability for the parent species in wastewater in the presence of biofilms. The newly identified isomeric forms of TPs particularly for methylone and mephedrone can be used as potential target biomarkers for WBE studies due to their specificity and detectability within a 24h residence time.

Comparison of phosphodiesterase type V inhibitors use in eight European cities through analysis of urban wastewater

In this work a step forward in investigating the use of prescription drugs, namely erectile dysfunction products, at European level was taken by applying the wastewater-based epidemiology approach. 24-h composite samples of untreated wastewater were collected at the entrance of eight wastewater treatment plants serving the catchment within the cities of Bristol, Brussels, Castellón, Copenhagen, Milan, Oslo, Utrecht and Zurich. A validated analytical procedure with direct injection of filtered aliquots by liquid chromatography-tandem mass spectrometry was applied. The target list included the three active pharmaceutical ingredients (sildenafil, tadalafil and vardenafil) together with (bio)transformation products and other analogues. Only sildenafil and its two human urinary metabolites desmethyl- and desethylsildenafil were detected in the samples with concentrations reaching 60 ng L^-1. The concentrations were transformed into normalized measured loads and the estimated actual consumption of sildenafil was back-calculated from these loads. In addition, national prescription data from five countries was gathered in the form of the number of prescribed daily doses and transformed into predicted loads for comparison. This comparison resulted in the evidence of a different spatial trend across Europe. In Utrecht and Brussels, prescription data could only partly explain the total amount found in wastewater; whereas in Bristol, the comparison was in agreement; and in Milan and Oslo a lower amount was found in wastewater than expected from the prescription data. This study illustrates the potential of wastewater-based epidemiology to investigate the use of counterfeit medication and rogue online pharmacy sales.

Stability of Illicit Drugs as Biomarkers in Sewers: From Lab to Reality

Systematic sampling and analysis of wastewater samples are increasingly adopted for estimating drug consumption in communities. An understanding of the in-sewer transportation and transformation of illicit drug biomarkers is critical for reducing the uncertainty of this evidence-based estimation method. In this study, biomarkers stability was investigated in lab-scale sewer reactors with typical sewer conditions. Kinetic models using the Bayesian statistics method were developed to simulate biomarkers transformation in reactors. Furthermore, a field-scale study was conducted in a real pressure sewer pipe with the systematical spiking and sampling of biomarkers and flow tracers. In-sewer degradation was observed for some spiked biomarkers over typical hydraulic retention time (i.e., a few hours). Results indicated that sewer biofilms prominently influenced biomarker stability with the retention time in wastewater. The fits between the measured and the simulated biomarkers transformation demonstrated that the lab-based model could be extended to estimate the changes of biomarkers in real sewers. Results also suggested that the variabilities of biotransformation and analytical accuracy are the two major contributors to the overall estimation uncertainty. Built upon many previous lab-scale studies, this study is one critical step forward in realizing wastewater-based epidemiology by extending biomarker stability investigations from laboratory reactors to real sewers.

Wastewater-based tracing of doping use by the general population and amateur athletes

The present study investigates the applicability of the chemical analysis of wastewater to assess the use of doping substances by the general population and amateur athletes. To this end, an analytical methodology that can identify and quantify a list of 15 substances from the groups of anabolic steroids, weight loss products, and masking agents in wastewater has been developed. The method uses solid phase extraction to increase the detection sensitivity of the target analytes, expected to be present at very low concentrations (ng L⁻¹ range), and decrease possible matrix interferences. Instrumental analysis is performed by liquid chromatography coupled to high-resolution mass spectrometry, allowing data acquisition in both full scan and tandem MS mode. The method has been successfully validated at two concentration levels (50 and 200 ng L⁻¹) with limits of quantification ranging between 0.7 and 60 ng L⁻¹, intra- and inter-day precision expressed as relative standard deviation below 15%, procedural recoveries between 60 and 160% and matrix effects ranging from 45 to 121%. The stability of the analytes in wastewater was evaluated at different storage temperatures illustrating the importance of freezing the samples immediately after collection. The application of the method to 24-h composite wastewater samples collected at the entrance of three wastewater treatment plants and one pumping station while different sport events were taking place revealed the presence in wastewater, and hence the use, of the weight loss substances ephedrine, norephedrine, methylhexanamine, and 2,4-dinitrophenol. The use of these stimulants was visible just prior and during the event days and in greater amounts than anabolic steroids or masking agents.

Graphical abstract

Wastewater Analysis for Community-Wide Drugs Use Assessment

Wastewater-based epidemiology (WBE) complements existing epidemiology-based estimation techniques and provides objective, evidence-based estimates of illicit drug use. After consumption, biomarkers - drugs and their metabolites - excreted to toilets and flushed into urban sewer networks can be measured in raw wastewater samples. The quantified loads can serve as an estimate for the collective consumption of all people contributing to the wastewater sample. This transdisciplinary approach, further explained in this chapter, has developed, matured and is now established for monitoring substances such as cocaine and amphetamine-type stimulants. Research currently underway is refining WBE to new applications including new psychoactive substances (NPS).