Obtaining process mass balances of pharmaceuticals and triclosan to determine their fate during wastewater treatment

Performance of an anaerobic-oxic-anoxic (AOA) system in the simultaneous removal of nutrients and triclosan and bacterial community

The constant presence of triclosan (TCS) in surface water and wastewater has been verified due to its application in several pharmaceutical and personal care products. Thus, removing this emerging contaminant is essential to minimize the contamination of water bodies. The anaerobic-aerobic-anoxic (AOA) system is an innovative alternative that combines the removal of nutrients and triclosan. This study focuses on the simultaneous removal of carbonaceous matter, nitrogen, phosphorus, and triclosan in a continuous pilot-scale AOA system from synthetic wastewater. The upflow system, in series, was operated at hydraulic retention time (HRT) of 8 h and a flowrate of 2.40 L h-1. Glucose (190 mg L-1) was added to the anoxic reactor as the external carbon source. Besides that, bacterial community structure was investigated using 16S rRNA sequencing in each reactor. The system achieved average removal efficiencies of 96% (14.03 g d-1) for Chemical Oxygen Demand (COD), 85% (2.64 g d-1) for Total Kjeldahl Nitrogen (TKN), 88% (1.40 g d-1) for Total Ammonia Nitrogen (TAN), 20% (0.12 g d-1) for Total Phosphorus (TP), and 93% (1.87 μg d-1) for Triclosan (TCS). The phyla Proteobacteria, Firmicutes, Bacteroidetes, and Chloroflexi were found in greater abundance. The main genera identified were Anaeromusa, Aeromonas, Azospira, Clostridium, and Lactococcus. The organisms related to phylum and genus corroborate the involved processes and the removal performance achieved. In addition, Lactococcus, Thermomonas, Ferruginibacter, and Dechloromonas were involved in triclosan biodegradation. The anaerobic-oxic-anoxic system successfully removed carbonaceous, nitrogenous matter, and triclosan, with glucose increasing the denitrifying activity.

Triclosan and related compounds in the environment: Recent updates on sources, fates, distribution, analytical extraction, analysis, and removal techniques

Triclosan (TCS) has been widely used in daily life because of its broad-spectrum antibacterial activities. The residue of TCS and related compounds in the environment is one of the critical environmental safety problems, and the pandemic of COVID-19 aggravates the accumulation of TCS and related compounds in the environment. Therefore, detecting TCS and related compound residues in the environment is of great significance to human health and environmental safety. The distribution of TCS and related compounds are slightly different worldwide, and the removal methods also have advantages and disadvantages. This paper summarized the research progress on the source, distribution, degradation, analytical extraction, detection, and removal techniques of TCS and related compounds in different environmental samples. The commonly used analytical extraction methods for TCS and related compounds include solid-phase extraction, liquid-liquid extraction, solid-phase microextraction, liquid-phase microextraction, and so on. The determination methods include liquid chromatography coupled with different detectors, gas chromatography and related methods, sensors, electrochemical method, capillary electrophoresis. The removal techniques in various environmental samples mainly include biodegradation, advanced oxidation, and adsorption methods. Besides, both the pros and cons of different techniques have been compared and summarized, and the development and prospect of each technique have been given.

Use of Fluorescence Spectroscopy and Chemometrics to Visualise Fluoroquinolones Photodegradation Major Trends: A Confirmation Study with Mass Spectrometry

In this work, we employed EEM-PARAFAC (fluorescence excitation-emission matrices-parallel factor analysis) as a low-cost tool to study the oxidation pathways of (fluoro)quinolones. Amounts of 12.5 μM of enrofloxacin (ENR), ciprofloxacin (CIP), ofloxacin (OFL), oxolinic acid (OA), and flumequine (FLU), as individual solutions, were irradiated under UVA light. A 5-component PARAFAC model was obtained, four of them related to the parent pollutants, named as ENR-like (including CIP), OFL-like, OA-like, and FLU-like, and an additional one related to photoproducts, called ENRox-like (with an emission red-shift with respect to the ENR-like component). Mass spectrometry was employed to correlate the five PARAFAC components with their plausible molecular structures. Results indicated that photoproducts presenting: (i) hydroxylation or alkyl cleavages exhibited fingerprints analogous to those of the parent pollutants; (ii) defluorination and hydroxylation emitted within the ENRox-like region; (iii) the aforementioned changes plus piperazine ring cleavage emitted within the OA-like region. Afterwards, the five antibiotics were mixed in a single solution (each at a concentration of 0.25 μM) in seawater, PARAFAC being also able to deconvolute the fingerprint of humic-like substances. This approach could be a potential game changer in the analysis of (fluorescent) contaminants of emerging concern removals in complex matrices, giving rapid visual insights into the degradation pathways.

Bioaccumulation potential of the tricyclic antidepressant amitriptyline in a marine Polychaete, Nereis virens

The continual discharge of pharmaceuticals from wastewater treatment plants (WWTPs) into the marine environment, even at concentrations as low as ng/L, can exceed levels that induce sublethal effects to aquatic organisms. Amitriptyline, a tricyclic antidepressant, is the most prescribed antidepressant in Norway, though the presence, potential for transport, and uptake by aquatic biota have not been assessed. To better understand the release and bioaccumulative capacity of amitriptyline, laboratory exposure studies were carried out with field-collected sediments. Influent and effluent composite samples from the WWTP of Stavanger (the 4th largest city in Norway) were taken, and sediment samples were collected in three sites in the proximity of this WWTP discharge at sea (WWTP discharge (IVAR), Boknafjord, and Kvitsøy (reference)). Polychaetes (Nereis virens) were exposed to field-collected sediments, as well as to Kvitsøy sediment spiked with 3 and 30 μg/g amitriptyline for 28 days. The WWTP influent and effluent samples had concentrations of amitriptyline of 4.93 ± 1.40 and 6.24 ± 1.39 ng/L, respectively. Sediment samples collected from IVAR, Boknafjord, and Kvitsøy had concentrations of 6.5 ± 3.9, 15.6 ± 12.7, and 12.7 ± 8.0 ng/g, respectively. Concentrations of amitriptyline were below the limit of detection in polychaetes exposed to sediment collected from Kvitsøy and IVAR, and 5.2 ± 2.8 ng/g in those exposed to Boknafjord sediment. Sediment spiked with 3 and 30 μg/g amitriptyline had measured values of 423.83 ± 33.1 and 763.2 ± 180.5 ng/g, respectively. Concentrations in worms exposed to the amended sediments were 9.5 ± 0.2 and 56.6 ± 2.2 ng/g, respectively. This is the first known study to detect measurable concentrations of amitriptyline in WWTP discharge in Norway and accumulation in polychaetes treated with field-collected sediments, suggesting that amitriptyline has the potential for trophic transfer in marine systems.

Pharmaceutical pollution of hospital effluents and municipal wastewaters of Eastern Canada

Quantification of drugs residues in wastewaters of different sources could help better understand contamination pathways, eventually leading to effluent regulation. However, limited data are available for hospital-derived wastewaters. Here, an analytical method based on automated on-line solid-phase extraction liquid chromatography tandem mass spectrometry (on-line SPE - UPLC-MS/MS) was developed for the quantification of multi-class pharmaceuticals in wastewaters. Filtrate phase and suspended solids (SPM) were both considered to evaluate the distribution of targeted analytes. Experimental design optimization involved testing different chromatographic columns, on-line SPE columns, and loading conditions for the filtrate phase, and different organic solvents and cleanup strategies for suspended solids. The selected methods were validated with suitable limits of detection, recovery, accuracy, and precision. A total of 30 hospital effluents and 6 wastewater treatment plants were sampled to evaluate concentrations in real field-collected samples. Certain pharmaceuticals were quantified at high levels such as caffeine at 670,000 ng/L in hospital wastewaters and hydroxyibuprofen at 49,000 ng/L in WWTP influents. SPM samples also had high contaminant concentrations such as ibuprofen at 31,000 ng/g in hospital effluents, fluoxetine at 529 ng/g in WWTP influents or clarithromycin at 295 ng/g in WWTP effluents. Distribution coefficients (K_d) and particle-associated fractions (Φ) indicate that pharmaceuticals tend to have better affinity to suspended solids in hospital wastewater than in municipal wastewaters. The results also bring arguments for at source treatment of these specific effluents before their introduction into urban wastewater systems.

Occurrence, transformation, bioaccumulation, risk and analysis of pharmaceutical and personal care products from wastewater: a review

Almost all aspects of society from food security to disease control and prevention have benefited from pharmaceutical and personal care products, yet these products are a major source of contamination that ends up in wastewater and ecosystems. This issue has been sharply accentuated during the coronavirus disease pandemic 2019 (COVID-19) due to the higher use of disinfectants and other products. Here we review pharmaceutical and personal care products with focus on their occurrence in the environment, detection, risk, and removal.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10311-022-01498-7.

Comparison of sorption models to predict analyte loss during sample filtration and evaluation of the impact of filtration on data quality

Although filtration has been a widely applied sample pretreatment step in environmental analytical chemistry, its impact on the quality of the data produced is often underappreciated in the scientific community. The objective of this literature review and modeling exercise was to examine nine existing sorption models with input parameters including hydrophobic interactions, pH, and structural features to predict the loss of analytes during wastewater filtration due to sorption to suspended solids and to assess the impact of filtration on data quality. Models' sorption estimates were further validated with a set of comprehensive metadata collected and analyzed from 20 peer-reviewed research papers that reported physical measurements of the suspended solids sorbed fraction of analytes obtained during wastewater filtration of contaminants of emerging concern (CECs). Data on the impact of filtration were obtained from the literature for 156 organic compounds reported both for the dissolved and particulate bound analyte mass. Approximately 40% of CECs (62/156) showed significant filtration loss (>20%) as a result of the removal of suspended solids during filtration. The loss of analyte mass due to filtration ranged from <1% for atenolol to >95% for acenaphthene. Collected literature data were then used to evaluate the utility of sorption modeling to predict analyte losses during sample pretreatment. Among nine sorption models, three were found to predict filtration loss of at least 70% of the CECs evaluated within a range of ±20% of the actually measured filtration loss of analytes, assuming a suspended solid concentration of 200 mg/L and a fraction of organic carbon in suspended solids of 0.43. Thus, sorption modeling can help reduce error when calculating mass loadings based on samples filtered before analysis. It is concluded that the estimates could be further improved by considering the following factors: ionic interactions, characteristics of the water-borne sorbents, and filtration media properties.

Assessment of the occurrence of 455 pharmaceutical compounds in sludge according to their physical and chemical properties: A review

Sludge agronomical reuse is of major interest due to the beneficial contribution of nutrients. However, it implies the introduction of unregulated pharmaceuticals into amended-soils and creates a controversial issue about sludge management. To limit their dissemination, it is essential to identify the compounds of interest and understand their attenuation mechanisms through the sludge processes. This paper summarizes the knowledge on 455 investigated pharmaceuticals among 32 therapeutical categories in amendable sludge matrices. It contributes to enlarging the list of commonly quantified compounds to 305 residues including 84 additional compounds compared to previous reviews. It highlights that sorption appears as the main mechanism controlling the occurrence of pharmaceuticals in sludge matrices and shows the considerable residual levels of pharmaceuticals reaching several mg/kg in dry weight. Antibiotics, stimulants, and antidepressants show the highest concentrations up to 232 mg/kg, while diuretics, anti-anxieties or anticoagulants present the lowest concentrations reaching up to 686 µg/kg. Collected data show the increase in investigated compounds as antifungals or antihistamines, and underline emerging categories like antidiabetics, antivirals, or antiarrhythmics. The in-depth analysis of the substantial database guides onto the pharmaceuticals that are the most likely to occur in these amendable matrices to assist future research.

Record of trace organic contaminants in a river sediment core: From historical wastewater management to historical use

Some trace organic contaminants (TrOCs) can be considered as ubiquitous contaminants since the 1950s, and the study of their historical distribution within river sediments allows us to better understand the temporal variation of the chemical quality of sediments, and make assumptions about the most insightful forcings impacting these distributions. In this study, the occurrence of 41 TrOCs of various classes (i.e. pharmaceutical products and pesticides) was studied in a sedimentary core sampled in a disused dock along the Seine River, France. This core covers a 60 year-long period between 1944 and 2003, and 23 TrOCs were detected at least once. Their concentrations mainly ranged between 1 and 10 ng g^-1 within the core, except for tetracycline that exhibited higher concentrations (~hundreds of ng·g^-1). The dating of the core, based on previous studies, enabled the characterization of the changes since 1945, potentially impacted by (i) the sewer connectivity, (ii) the upgrading of wastewater treatment technologies, (iii) historical modifications in the use of each TrOC, and (iv) the sedimentary composition. In every case the deepest occurrence of each TrOC in the core matched its market authorization date, indicating the potential of TrOC to be used as chronomarkers. This study also reveals that the recent upgrading of wastewater treatment technologies within the watershed decreased the concentrations of each TrOC, despite an increase in TrOC diversity in the most recent years.

Ecotoxicity and biodegradation of the bacteriostatic 3,3',4',5-tetrachlorosalicylanilide (TSCA) compared to the structurally similar bactericide triclosan

This article studies the ecotoxicity of 3,3',4',5-tetrachlorosalicylanilide (TCSA) using different bioassays and examines its fate in activated sludge batch experiments. Despite of the common use of TCSA as chemical uncoupler in wastewater treatment systems and as preservative in several products, limited data has been published for its ecotoxicity, while no information is available for its biodegradation. Among different bioassays, the highest toxicity of TSCA was noticed for Daphna magna (48-h LC₅₀: 0.054 mg L^-1), followed by Vibrio fischeri (15-min EC₅₀: 0.392 mg L^-1), Lemna minor, (7-d EC₅₀: 5.74 mg L^-1) and activated sludge respiration rate (3-h EC₅₀: 31.1 mg L^-1). The half-life of TSCA was equal to 7.3 h in biodegradation experiments with activated sludge, while use of mass balances showed that 90% of this compound is expected to be removed in an aerobic activated sludge system, mainly due to biodegradation. A preliminary risk assessment of TSCA using the Risk Quotient methodology showed possible ecological threat in rivers where wastewater is diluted up to 100-fold. Comparison with the structurally similar 5-chloro-2-(2,4-dichlorophenoxy)phenol (triclosan, TCS) showed that both compounds have similar biodegradation potential and seem to cause analogous toxicity to Vibrio fischeri and activated sludge. Specifically, TCS was biodegraded quite rapidly by activated sludge (half-life: 6.2 h), while EC₅₀ values equal to 0.134 mg L^-1 and 39.9 mg L^-1 were calculated for Vibrio fischeri, and activated sludge respiration rate. Future research should focus on monitoring of TSCA concentrations in the environment and study its effects in long-term toxicity and bioaccumulation tests.

New insights on the combined removal of antibiotics and ARGs in urban wastewater through the use of two configurations of vertical subsurface flow constructed wetlands

The occurrence and removal of 49 antibiotics and 11 selected antibiotic resistance genes (ARGs) were investigated in 2 vertical subsurface flow (VF) constructed wetlands (1.5 m² each): an unsaturated (UVF) unit and a partially saturated (SVF) unit (0.35 m saturated out of 0.8 m) operating in parallel and treating urban wastewater. Thirteen antibiotics were detected in influent wastewater, 6 of which were present in all samples. The SVF showed statistical significance on the removal of 4 compounds (namely ciprofloxacin, ofloxacin, pipemidic acid and azithromycin), suggesting that the wider range of pH and/or redox conditions of this configuration might promote the microbial degradation of some antibiotics. In contrast, the concentration of the latter (except pipemidic acid) and also clindamycin was higher in the effluent than in the influent of the UVF. Five ARGs were detected in influent wastewater, sul1 and sul2, bla_TEM, ermB and qnrS. All of them were detected also in the biofilm of both wetlands, except qnrS. Average removal rates of ARGs showed no statistical differences between both wetland units, and ranged between 46 and 97% for sul1, 33 and 97% for sul2, 9 and 99% for ermB, 18 and 97% for qnrS and 11 and 98% for bla_TEM.

Micropollutant fluxes in urban environment - A catchment perspective

This study provided a holistic understanding of the sources, fate and behaviour of 142 compounds of emerging concern (CECs) throughout a river catchment impacted by 5 major urban areas. Of the incoming 169.3 kg d^-1 of CECs entering the WwTWs, 167.9 kg d^-1 were present in the liquid phase of influent and 1.4 kg d^-1 were present in the solid phase (solid particulate matter, SPM). Analysis of SPM was important to determine accurate loads of incoming antidepressants and antifungal compounds, which are primarily found in the solid phase. Furthermore, these classes and the plasticiser, bisphenol A (BPA) were the highest contributors to CEC load in digested solids. Population normalised loads showed little variation across the catchment at 154 ± 12 mg d^-1 inhabitant^-1 indicating that population size is the main driver of CECs in the studied catchment. Across the catchment 154.6 kg d^-1 were removed from the liquid phase during treatment processes. CECs discharged into surface waters from individual WwTWs contributed between 0.19 kg d^-1 at WwTW A to 7.3 kg d^-1 at WwTW E, which correlated strongly with the respective contributing populations. Spatial and temporal variations of individual CECs and their respective classes were found in WwTW influent (both solid (influent_SPM) and liquid phases (influent_AQ)) throughout the catchment, showing that different urban areas impact the catchment in different ways, with key variables being lifestyle, use of over-the-counter pharmaceuticals and industrial activity. Understanding of both spatial and temporal variation of CECs at the catchment level helped to identify possible instances of direct disposal, as in the case of carbamazepine. Analysis of surface waters throughout the catchment showed increasing mass loads of CECs from upstream of WwTW A to downstream at WwTW D, showing clear individual contributions from WwTWs. Many CECs were ubiquitous throughout the river water in the catchment. Daily loads ranged from 0.005 g d^-1 (ketamine, WwTW A) up to 1890.3 g d^-1 (metformin, WwTW C) for the 84/138 CECs that were detected downstream of the WwTWs. For metformin this represents the equivalent of ∼1,890 tablets (1,000 mg per tablet) dissolved in the river water downstream of WwTW C.

Assessing hospital impact on pharmaceutical levels in a rural 'source-to-sink' water system

It is widely recognised that inadequate removal of pharmaceuticals in wastewater may lead to their presence in surface waters. Hospitals are key point-sources for pharmaceuticals entering municipal waterways, and rural hospitals are of concern as receiving wastewater treatment plants (WWTPs) may be smaller, less advanced and thus less efficient. While most research has focused on urban settings, here we present results from a rural ''source-to-sink'' study around a hospital. The aim was to determine the contribution of pharmaceuticals discharged to a municipal wastewater system, and, to assess pharmaceutical removal efficiency in the WWTP. Samples were collected daily for one month to assess water quality and pharmaceuticals in the broader water cycle: (i) raw water supply; (ii) treated hospital tap water; (iii) hospital wastewater discharge; (iv) combined WWTP influent; and (v) final WWTP effluent. Target compounds included analgesics/antiinflammatories, antibiotics, psychiatric drugs, and a synthetic estrogen hormone. Concentrations ranged from: 3 ng/L (carbamazepine) to 105,910 ng/L (paracetamol) in hospital discharge; 5 ng/L (ibuprofen) to 105,780 ng/L (paracetamol) in WWTP influent; and 60 ng/L (clarithromycin) to 36,201 ng/L (paracetamol) in WWTP effluent. WWTP removal ranged from 87% (paracetamol) to <0% (carbamazepine and clarithromycin), and significant correlations with water quality characteristics and WWTP flow data were observed for some compounds. Results suggested that the hospital is an important source of certain pharmaceuticals entering municipal wastewater, and associated water quality parameters are impacted. Pharmaceutical persistence in the WWTP effluent highlighted the direct pathway these compounds have into receiving surface water, where their impact remains uncharacterised. Rural regions may face future challenges mitigating environmental risk as WWTP infrastructure ages, populations grow and pharmaceutical use and diversity continue to increase.

Occurrence and treatment of contaminants of emerging concern in the African aquatic environment: Literature review and a look ahead

Awareness about the rising detection and reported (eco)toxicological effects of contaminants of emerging concern (CECs, e.g. pharmaceuticals and personal care products - PPCPs - and modern pesticides) in the aquatic environment is growing. CECs are increasingly reported in the African aquatic environment, although the amount of data available is still limited. In this work, a comprehensive review is presented on the occurrence of CECs in wastewater, sludge, surface water, sediment, groundwater and drinking water of Africa. Further attention is given to the performance of wastewater stabilization ponds (WSPs) and trickling filters (TF) with respect to CECs removal. For the first time, we also look at the state of knowledge on the performance of point-of-use technologies (POUs) regarding the removal of CECs in drinking water. Generally, CECs in Africa occur at the same order of magnitude as in the Western world. However, for particular groups of compounds and at specific locations such as informal settlements, clearly higher concentrations are reported in Africa. Whereas antiretroviral and antimalarial drugs are rarely detected in the Western world, occurrence patterns in Africa reveal concentrations up to >100 μg L^-1. Removal efficiencies of WSPs and TFs focus mainly on PPCPs and vary significantly, ranging from no removal (e.g. carbamazepine) to better than 99.9% (e.g. paracetamol). Despite the rising adoption of POUs, limited but promising information is available on their performance regarding CECs treatment in drinking water, particularly for the low-cost devices (e.g. ceramic filters and solar disinfection - SODIS) being adopted in Africa and other developing countries.

Diethylhexyl phthalate removal in full scale activated sludge plants: Effect of operational parameters

Removal of emerging contaminants (ECs) is a serious concern in wastewater industry especially for public acceptance of reclaimed water. Diethylhexyl phthalate (DEHP) is one of the ubiquitous and detectable plasticizers in municipal wastewater across the globe. Water Framework Directive (2000/60/EC) has prioritized it for the establishment of discharge regulations. A cost-effective strategy, especially for developing nations, may be the re-engineering of the existing biological process for the simultaneous removal of ECs and conventional pollutants. Wastewater treatment plants are one of the main sources for DEHP occurrence in surface water. In this study, possible role of activated sludge process operational parameters in effective removal of DEHP was assessed. Principal component analysis of occurrence data showed dissimilarity with the organic and nutrient characteristics of sewage. DEHP concentration in more than half (55%) of treated wastewater samples was more than environmental quality standard value for inland and surface water bodies (1.3 μg/L). At a mixed liquor suspended solid (MLSS) concentration range of 3461-4972 mg/L, overall removal was 23.9 μg/gMLSS.d (92 ± 6%) with biodegraded portion as 22.4 μg/gMLSS.d (85 ± 4%) and sorbed portion of 1.5 μg/gMLSS.d (7 ± 4%). DEHP removal showed an increasing trend at higher oxygen uptake rates (OUR) of sludge with DEHP removal of 8.1  μg DEHP/gMLSS.d (70 ± 6%), in the OUR range of 20-28mgO₂/L/h. Increase in overall removal of DEHP showed a positive correlation (r² = 0.7) with increasing sludge retention time (SRT) and so does the decreasing food to microorganism (F/M) ratio with increasing removal of DEHP (r² = 0.8). A temperature decrease of 13 °C caused a decrease of 30% in overall removal of DEHP.

Occurrence and removal of sulfonamides and their acetyl metabolites in a biological aerated filter (BAF) of wastewater treatment plant in Xiamen, South China

Most sulfonamides, widely used around the world, are excreted via feces and urine along with their metabolites in humans and animals. Therefore, understanding the potential removal pathway of sulfonamides and their metabolites in wastewater treatment systems is of importance. The occurrence and fate of four sulfonamides and their acetyl metabolites in wastewater and sludge in a biological aerated filter in Xiamen city were evaluated. Six of the target compounds were detected in wastewater, but only parent compounds were detected in sludge. The highest concentration in wastewater was acetyl-sulfamethoxazole (Ac-SMZ) with a concentration of 75.2 ng/L. Removal efficiency and mass load in wastewater treatment systems were calculated. In terms of the overall removal efficiency, they ranged from 24.4 to 100%. The removal efficiencies of sulfamerazine (SM1), sulfamethazine (SM2), and sulfadiazine (SD) were up to 100% while N-acetyl sulfamerazine (Ac-SM1) showed the lowest removal efficiency. Biodegradation was the dominant remove pathway according to the mass balance analysis while SD and SM2 were sludge adsorption. The results can provide an insight into the fate of target sulfonamides in BAF systems and provide data to assess their potential ecological risks.

Insights into the Fate and Removal of Antibiotics in Engineered Biological Treatment Systems: A Critical Review

Antibiotics, the most frequently prescribed drugs of modern medicine, are extensively used for both human and veterinary applications. Antibiotics from different wastewater sources (e.g., municipal, hospitals, animal production, and pharmaceutical industries) ultimately are discharged into wastewater treatment plants. Sorption and biodegradation are the two major removal pathways of antibiotics during biological wastewater treatment processes. This review provides the fundamental insights into sorption mechanisms and biodegradation pathways of different classes of antibiotics with diverse physical-chemical attributes. Important factors affecting sorption and biodegradation behavior of antibiotics are also highlighted. Furthermore, this review also sheds light on the critical role of extracellular polymeric substances on antibiotics adsorption and their removal in engineered biological wastewater treatment systems. Despite major advancements, engineered biological wastewater treatment systems are only moderately effective (48-77%) in the removal of antibiotics. In this review, we systematically summarize the behavior and removal of different antibiotics in various biological treatment systems with discussion on their removal efficiency, removal mechanisms, critical bioreactor operating conditions affecting antibiotics removal, and recent innovative advancements. Besides, relevant background information including antibiotics classification, physical-chemical properties, and their occurrence in the environment from different sources is also briefly covered. This review aims to advance our understanding of the fate of various classes of antibiotics in engineered biological wastewater treatment systems and outlines future research directions.

The influence of solid-liquid coefficient in the fate of pharmaceuticals and personal care products in aerobic wastewater treatment

Wastewater treatment plants (WWTPs) are considered to be a source of environmental contamination by micropollutants, especially from pharmaceuticals and personal care products (PCPs). The pathway of those compounds during sewage treatment has been investigated, but data from real-scale WWTPs is still missing (for example, the values of the solid-liquid coefficient (K_d) during treatment). This paper uses the K_d values for some pharmaceuticals and PCPs (fenofibrate, gemfibrozil, propranolol, metoprolol, salicylic acid, acetylsalicylic acid, ibuprofen, diclofenac, naproxen, fenoprofen, caffeine, triclosan, methylparaben, ethylparaben, propylparaben, butylparaben, and benzylparaben) to describe the micropollutants' behavior in the treatment process. In order to attain this data, an aerobic wastewater treatment plant located in Brazil was studied. Six samplings were carried out and a mass balance was performed, associating the concentrations of the micropollutants in the liquid phase with the solid phase (sludge and suspended solids). Of all the compounds analyzed, caffeine was the most biodegradable pollutant, as almost 98% of its mass was biodegraded. In contrast, triclosan had the highest load in sludge (median of 163.0 mg day^-1) and adsorbed in SS (median of 0.593 mg day^-1) at the output. Summing up, each micropollutant had a specific way to be removed during wastewater treatment.

Monitoring and mass balance analysis of endocrine disrupting compounds and their transformation products in an anaerobic-anoxic-oxic wastewater treatment system in Xiamen, China

We investigated the occurrence, removal and mass balance of 8 endocrine disrupting compounds (EDCs), including estrone (E1), estradiol (E2), estriol (E3), ethinylestradiol (EE2), triclosan (TCS), triclocarbon (TCC), 4-n-nonyl phenol (NP) and 4-n-octyl phenol (OP), along with 5 of their transformation products (TPs), including 4-hydroxy estrone (4-OH E1), 4-hydroxy estradiol (4-OH E2), methyl triclosan (MeTCS), carbanilide (NCC), dichlorocarbanilide (DCC) in a wastewater treatment plant. Generally, E3 showed the highest concentrations in wastewater with median value of 514 ng/L in influent, while TCS and TCC showed highest level in sludge and suspended solids (SS) with median value of 960 and 724 μg/kg, respectively. Spatial variations were observed along each unit of the wastewater treatment processes for dissolved analytes in wastewater and adsorbed analytes in suspended solids and sludge. Special emphasis was placed to understand the mass load of EDCs and their TPs to the wastewater treatment unit and mass loss during the wastewater treatment processes. Mass loss based on both aqueous and suspended phase concentration revealed that majority of these chemicals were significantly removed during the treatment process except for TCS, TCC, and three of their TPs (MeTCS, NCC, DCC), which were released or generated during the treatment process. Mass load results showed that 42.4 g of these EDCs and their TPs entered this wastewater treatment system daily via influent, whereas 6.15 g and 7.60 g were discharged through effluent and sludge.

Monitoring, mass balance and fate of pharmaceuticals and personal care products in seven wastewater treatment plants in Xiamen City, China

The occurrence and fate of pharmaceuticals and personal care products (PPCPs) was investigated in seven wastewater treatment plants (WWTPs) in Xiamen City, China. Special emphasis was placed on their co-occurrence and the mass balances of both dissolved and adsorbed PPCPs in influent, effluent, and sludge samples. Results showed that PPCPs were widely detected and their co-occurrence was observed both in the wastewater and sludge that can be attributed to either their similar usage or similar physicochemical properties. These results further emphasize that some specific PPCPs have the potential as indicators or surrogate compounds to reduce the number of targeted PPCPs. The occurrence and distribution of PPCPs also showed strong spatial variations, as the PPCP mass loads per inhabitant were positively correlated with the urbanization levels. Both the removal efficiencies of dissolved PPCPs from the aqueous phase and mass loss proportion of the total PPCPs were evaluated and compared. Overall, a measured total amount of 8500 g PPCPs entered the seven WWTPs daily via influent with 6640 g in the dissolved form, while 3450 g left the WWTPs. The large mass loads of antibiotics in the sludge and effluents indicated their potential adverse effects to the receiving environment.

Fate of triclosan in laboratory-scale activated sludge reactors - Effect of culture acclimation

Triclosan (TCS); a widely used antimicrobial biocide, exists in several pharmaceutical and personal care products. Due to its wide usage, TCS is detected in wastewater at varying concentrations. Biological treatability of TCS and its effect on chemical oxygen demand (COD) removal efficiency were investigated running laboratory-scale pulse-fed sequencing batch reactors with acclimated and non-acclimated cultures. The culture was acclimatized to TCS by gradually increasing its concentration in the synthetic feed wastewater from 100 ng/L to 100 mg/L. There were no effects of TCS on COD removal efficiency up to the TCS concentration of 500 ng/L for both acclimatized and non-acclimatized cases. However, starting from a concentration of 1 mg/L, TCS affected the COD removal efficiency adversely. This effect was more pronounced with non-acclimatized culture. The decrease in the COD removal efficiency reached to 47% and 42% at the TCS concentration of 100 mg/L, under acclimation and non-acclimation conditions respectively. Adsorption of TCS into biomass was evidenced at higher TCS concentrations especially with non-acclimated cultures. 2,4-dichlorophenol and 2,4-dichloroanisole were identified as biodegradation by-products. The occurrence and distribution of these metabolites in the effluent and sludge matrices were found to be highly variable depending, especially, on the culture acclimation conditions.

Predicting the fate of micropollutants during wastewater treatment: Calibration and sensitivity analysis

The presence of micropollutants in the environment and their toxic impacts on the aquatic environment have raised concern about their inefficient removal in wastewater treatment plants. In this study, the fate of micropollutants of four different classes was simulated in a conventional activated sludge plant using a bioreactor micropollutant fate model coupled to a settler model. The latter was based on the Bürger-Diehl model extended for the first time to include micropollutant fate processes. Calibration of model parameters was completed by matching modelling results with full-scale measurements (i.e. including aqueous and particulate phase concentrations of micropollutants) obtained from a 4-day sampling campaign. Modelling results showed that further biodegradation takes place in the sludge blanket of the settler for the highly biodegradable caffeine, underlining the need for a reactive settler model. The adopted Monte Carlo based calibration approach also provided an overview of the model's global sensitivity to the parameters. This analysis showed that for each micropollutant and according to the dominant fate process, a different set of one or more parameters had a significant impact on the model fit, justifying the selection of parameter subsets for model calibration. A dynamic local sensitivity analysis was also performed with the calibrated parameters. This analysis supported the conclusions from the global sensitivity and provided guidance for future sampling campaigns. This study expands the understanding of micropollutant fate models when applied to different micropollutants, in terms of global and local sensitivity to model parameters, as well as the identifiability of the parameters.

Occurrence, fate, and mass balance of different classes of pharmaceuticals and personal care products in an anaerobic-anoxic-oxic wastewater treatment plant in Xiamen, China

In this study, the occurrence and fate of 49 pharmaceuticals and personal care products (PPCPs) were investigated in an anaerobic-anoxic-oxic (A2/O) wastewater treatment plant (WWTP) for seven consecutive days using 24-h composite sampling technique. Special emphasis was placed to understand the distribution of PPCPs in dissolved and adsorbed phase, and to evaluate PPCP fate in different treatment units. Among the 49 PPCPs, 40 PPCPs in influent, 36 in effluent, 29 in sludge and 23 in suspended solids were detected at least once during sampling. Non-steroidal anti-inflammatory drugs (NSAIDs) and a stimulant were predominant PPCPs in influent whereas antibiotics were predominant in sludge, effluent and suspended solids. Removal efficiencies from the aqueous phase based on the dissolved PPCPs showed variable contribution in removing different PPCPs under screen and grit chamber, anaerobic treatment, anoxic treatment, oxic treatment and sedimentation-UV treatments, with the highest removal percentage by anaerobic process in terms of both individual and overall treatment. Mass load analysis showed that 352 g PPCPs enter the WWTP daily while 14.5 g and 58.1 g were discharged through effluent and excess sludge to the receiving sea water and soil applications, respectively. Mass balance analysis based on both aqueous and suspended PPCPs showed 280 g (79.4%) mass of influent PPCPs was lost along the wastewater treatment processes, mainly due to degradation/transformation.

Estimating removals of contaminants of emerging concern from wastewater treatment plants: The critical role of wastewater hydrodynamics

Accurate data is needed to evaluate the capacity of wastewater treatments plants (WWTPs) to remove contaminants of emerging concern (CECs). The variability of CEC removals reported in the literature has raised questions about the methods used to estimate removals. In this study, we used the recently proposed "fractionated approach" to account for the influence of hydrodynamics in WWTPs and applied this method for estimating the removal of 23 target CECs. Data on the conductivity and temperature of wastewater at two WWTPs were used to determine the hydraulic model that best described the flow regime of treatment units. Composite samples (24-h) were collected at different stages of treatment over successive days. The concentrations of the target compounds in wastewater were determined by liquid chromatography with mass spectrometry. Different hydraulic models were necessary to define the hydrodynamics at the two WWTPs, resulting in different load fractions to be used in the calculation of removals. For WWTP A, that has a primary clarifier, all target CECs, except triclosan, were poorly removed during this step at efficiencies <30%. On the other hand, the activated sludge treatment unit at both WWTPs removed most target CECs at >70%. This study expanded the application of the fractionated approach to compare the hydraulics of two treatment trains of different configurations, including primary and secondary treatment. It demonstrated the sensitivity of the method to account for variations between the different treatment units. Reliable removals of an extended list of CECs in primary and secondary treatment were also provided in this study.

Influence of the natural colloids on the multi-phase distributions of antibiotics in the surface water from the largest lake in North China

Understanding antibiotic adsorption on natural colloids is crucial for prediction of the behavior, bioavailability and toxicity of antibiotics in natural waters. In the present study, the filtered water (dissolved phase, <0.7μm) was further separated into colloidal phase (1kDa-0.7μm) and soluble phase (<1kDa) by cross-flow ultrafiltration (CFUF), and the spatial-temporal variation and distribution of six antibiotics in multi-phases were investigated in Baiyangdian Lake. Results indicated that antibiotic concentrations differed significantly with sampling location and time. The mean concentrations of antibiotics ranged between 13.65 and 320.44ngL^-1 in the dissolved phase, and the colloidal phase accounted for 4.7-49.8% of all antibiotics, suggesting that natural colloids play an important role as carriers of antibiotics in aquatic environments. Because of the influence of colloids, the partition coefficients of antibiotics between suspended particulate matter (SPM) and soluble phase (intrinsic partition coefficients, K_p^int) were found to be 6.18-109.60% higher than corresponding observed partition coefficients (K_p^obs, between SPM and dissolved phase). The mean partition coefficients between colloidal and soluble phase (K_col.) ranged between 6218 and 117,374Lkg^-1, which were 1-2 orders of magnitude greater than K_p^int values. In order to explore the adsorption mechanism of antibiotics on colloids, Pearson's correlations were performed. The results showed that log K_col. were negatively correlated with cations in natural colloids; especially with Mg (r, -0.643, P<0.01) for oxytetracycline (OTC), and with both Ca (-0.595, P<0.01) and Mg (-0.593, P<0.01) in the case of ofloxacin (OFL). This result revealed that the competitive effect between cations and antibiotics was the main factor influencing the adsorption behavior of antibiotics on natural colloids in the lake.

Fate and mass balance of contaminants of emerging concern during wastewater treatment determined using the fractionated approach

Contaminants of emerging concern (CECs) are often poorly removed from wastewater using conventional treatment technologies and there is limited understanding of their fate during treatment. Inappropriate sampling strategies lead to inaccuracies in estimating removals of CECs. In this study, we used the "fractionated approach" that accounts for the residence time distribution (RTD) in treatment units to investigate the fate of 26 target CECs in a municipal wastewater treatment plant (WWTP) that includes primary, secondary and tertiary treatment steps. Prior hydraulic calibration of each treatment unit was performed. Wastewater and sludge samples were collected at different locations along the treatment train and the concentrations of target CECs were measured by liquid chromatography mass spectrometry. The most substantial aqueous removal occurred during activated sludge treatment (up to 99%). Removals were <50% in the primary clarifier and tertiary rotating biological contactors (RBCs) and up to 70% by sand filtration. Mass balance calculations demonstrated that (bio)degradation accounted for up to 50% of the removal in the primary clarifier and 100% in activated sludge. Removal by sorption to primary and secondary sludge was minimal for most CECs. Analysis of the selected metabolites demonstrated that negative removals obtained could be explained by transformations between the parent compound and their metabolites. This study contributes to the growing literature by applying the fractionated approach to calculate removal of different types of CECs across each wastewater treatment step. An additional level of understanding of the fate of CECs was provided by mass balance calculations in primary and secondary treatments.

Comparison of biological and advanced treatment processes for ciprofloxacin removal in a raw hospital wastewater

The treatability of ciprofloxacin (CIP) antibiotic was investigated using a single aerobic, a single anaerobic, an anaerobic/aerobic sequential reactor system, a sonicator and a photocatalytic reactor with TiO2 nanoparticles in a raw hospital wastewater in Izmir, Turkey. The effects of increasing organic loading on the performance of all biological systems were investigated, while the effects of power and time on the yields of sonication and photocatalysis were determined. The maximum COD and CIP yields were 95% and 83% in anaerobic/aerobic sequential reactor system at an HRT of 10 days and at an OLR of 0.19 g COD/L × day after 50 days of incubation, respectively. The maximum CH4 gas production was 580 mL day(-1) at an HRT of 6.7 days. The maximum COD and CIP yields were 95% and 81% after 45 min sonication time at a power of 640 W and a frequency of 35 kHz while the maximum yield of COD and CIP were 98% and 88% after 45 min UV irradiation time with a UV power of 210 W using 0.5 g L(-1) TiO2. Among the aforementioned treatment processes, it was found that the highest treatment yields for COD (98%) and CIP (88%) pollutants were obtained with the photocatalytic process due to high OH((●)) radical productions.

Removal of Antibiotics in Biological Wastewater Treatment Systems-A Critical Assessment Using the Activated Sludge Modeling Framework for Xenobiotics (ASM-X)

Many scientific studies present removal efficiencies for pharmaceuticals in laboratory-, pilot-, and full-scale wastewater treatment plants, based on observations that may be impacted by theoretical and methodological approaches used. In this Critical Review, we evaluated factors influencing observed removal efficiencies of three antibiotics (sulfamethoxazole, ciprofloxacin, tetracycline) in pilot- and full-scale biological treatment systems. Factors assessed include (i) retransformation to parent pharmaceuticals from e.g., conjugated metabolites and analogues, (ii) solid retention time (SRT), (iii) fractions sorbed onto solids, and (iv) dynamics in influent and effluent loading. A recently developed methodology was used, relying on the comparison of removal efficiency predictions (obtained with the Activated Sludge Model for Xenobiotics (ASM-X)) with representative measured data from literature. By applying this methodology, we demonstrated that (a) the elimination of sulfamethoxazole may be significantly underestimated when not considering retransformation from conjugated metabolites, depending on the type (urban or hospital) and size of upstream catchments; (b) operation at extended SRT may enhance antibiotic removal, as shown for sulfamethoxazole; (c) not accounting for fractions sorbed in influent and effluent solids may cause slight underestimation of ciprofloxacin removal efficiency. Using tetracycline as example substance, we ultimately evaluated implications of effluent dynamics and retransformation on environmental exposure and risk prediction.

Attenuation of pharmaceuticals and their transformation products in a wastewater treatment plant and its receiving river ecosystem

Pharmaceuticals are designed to improve human and animal health, but may also be a threat to freshwater ecosystems, particularly after receiving urban or wastewater treatment plant (WWTP) effluents. Knowledge on the fate and attenuation of pharmaceuticals in engineered and natural ecosystems is rather fragmented, and comparable methods are needed to facilitate the comprehension of those processes amongst systems. In this study the dynamics of 8 pharmaceuticals (acetaminophen, sulfapyridine, sulfamethoxazole, carbamazepine, venlafaxine, ibuprofen, diclofenac, diazepam) and 11 of their transformation products were investigated in a WWTP and the associated receiving river ecosystem. During 3 days, concentrations of these compounds were quantified at the influents, effluents, and wastage of the WWTP, and at different distances downstream the effluent at the river. Attenuation (net balance between removal and release from and to the water column) was estimated in both engineered and natural systems using a comparable model-based approach by considering different uncertainty sources (e.g. chemical analysis, sampling, and flow measurements). Results showed that pharmaceuticals load reduction was higher in the WWTP, but attenuation efficiencies (as half-life times) were higher in the river. In particular, the load of only 5 out of the 19 pharmaceuticals was reduced by more than 90% at the WWTP, while the rest were only partially or non-attenuated (or released) and discharged into the receiving river. At the river, only the load of ibuprofen was reduced by more than 50% (out of the 6 parent compounds present in the river), while partial and non-attenuation (or release) was observed for some of their transformation products. Linkages in the routing of some pharmaceuticals (venlafaxine, carbamazepine, ibuprofen and diclofenac) and their corresponding transformation products were also identified at both WWTP and river. Finally, the followed procedure showed that dynamic attenuation in the coupled WWTP-river system could be successfully predicted with simple first order attenuation kinetics for most modeled compounds.

Organic micropollutants (OMPs) in natural waters: Oxidation by UV/H2O2 treatment and toxicity assessment

Organic micropollutants (OMPs) are ubiquitous in natural waters even in places where the human activity is limited. The presence of OMPs in natural water sources for human consumption encourages the evaluation of different water purification technologies to ensure water quality. In this study, the Biobío river (Chile) was selected since the watershed includes urban settlements and economic activities (i.e. agriculture, forestry) that incorporate a variety of OMPs into the aquatic environment, such as pesticides, pharmaceuticals and personal care products. Atrazine (herbicide), caffeine (psychotropic), diclofenac (anti-inflammatory) and triclosan (antimicrobial) in Biobío river water and in different stages of a drinking and two wastewater treatment plants downstream Biobío river were determined using solid phase extraction (SPE) and liquid chromatography/tandem mass spectrometry (LC-MS/MS) and electrospray ionization (ESI). Quantification of these four compounds showed concentrations in the range of 8 ± 2 to 55 ± 10 ng L(-1) in Biobío river water, 11 ± 2 to 74 ± 21 ng L(-1) in the drinking water treatment plant, and 60 ± 10 to 15,000 ± 1300 ng L(-1) in the wastewater treatment plants. Caffeine was used as an indicator of wastewater discharges. Because conventional water treatment technologies are not designed to eliminate some emerging organic pollutants, alternative treatment processes, UV and UV/H2O2, were employed. The transformation of atrazine, carbamazepine (antiepileptic), diclofenac and triclosan was investigated at laboratory scale. Both processes were tested at different UV doses and the Biobío river water matrix effects were evaluated. Initial H2O2 concentration used was 10 mg L(-1). Results showed that, the transformation profile obtained using UV/H2O2 at UV doses up to 900 mJ cm(-2), followed the trend of diclofenac > triclosan > atrazine > carbamazepine. Furthermore acute toxicity tests with Daphnia magna were carried out after UV/H2O2 treatments of the OMPs mixture studied. At the lower UV doses tested (300 mJ cm(-2)) a higher toxicity was observed, suggesting the formation of toxic intermediates in the course of the reaction. As expected, at higher UV doses the toxicity declined. Considering the treatment of the mixture of ATZ, CBZ, DCL and TCS with a UV dose of 1200 mJ cm(-2) and 10 mg L(-1) of H2O2 the acute toxicity results exhibits values for Daphnia magna immobilization equal to 20 and 42% evaluated after 24 and 48 h, respectively.

Mercury and antimony in wastewater: fate and treatment

It is important to understand the fate of Hg and Sb within the wastewater treatment process so as to examine potential treatment options and to ensure compliance with regulatory standards. The fate of Hg and Sb was investigated for an activated sludge process treatment works in the UK. Relatively high crude values (Hg 0.092 μg/L, Sb 1.73 μg/L) were observed at the works, whilst low removal rates within the primary (Hg 52.2 %, Sb 16.3 %) and secondary treatment stages (Hg 29.5 %, Sb -28.9 %) resulted in final effluent concentrations of 0.031 μg/L for Hg and 2.04 μg/L for Sb. Removal of Hg was positively correlated with suspended solids (SS) and chemical oxygen demand (COD) removal, whilst Sb was negatively correlated. Elevated final effluent Sb concentrations compared with crude values were postulated and were suggested to result from Sb present in returned sludge liquors. Kepner Tregoe (KT) analysis was applied to identify suitable treatment technologies. For Hg, chemical techniques (specifically precipitation) were found to be the most suitable whilst for Sb, adsorption (using granulated ferric hydroxide) was deemed most appropriate. Operational solutions, such as lengthening hydraulic retention time, and treatment technologies deployed on sludge liquors were also reviewed but were not feasible for implementation at the works.

Mass flow of antibiotics in a wastewater treatment plant focusing on removal variations due to operational parameters

Wastewater treatment plants (WWTPs) are not designed to purposefully eliminate antibiotics and therefore many previous investigations have been carried out to assess their fate in biological wastewater treatment processes. In order to consolidate previous findings regarding influencing factors like the solid and hydraulic retention time an intensive monitoring was carried out in a municipal WWTP in Germany. Over a period of 12months daily samples were taken from the in- and effluent as well as diverse sludge streams. The 14 selected antibiotics and one metabolite cover the following classes: cephalosporins, diaminopyrimidines, fluoroquinolones, lincosamide, macrolides, penicillins, sulfonamides and tetracyclines. Out of the 15 investigated substances, the removal of only clindamycin and ciprofloxacin show significant correlations to SRT, temperature, HRT and nitrogen removal. The dependency of clindamycin's removal could be related to the significant negative removal (i.e. production) of clindamycin in the treatment process and was corrected using the human metabolite clindamycin-sulfoxide. The average elimination was adjusted from -225% to 3% which suggests that clindamycin can be considered as an inert substance during the wastewater treatment process. Based on the presented data, the mass flow analysis revealed that macrolides, clindamycin/clindamycin-sulfoxide and trimethoprim were mainly released with the effluent, while penicillins, cephalosporins as well as sulfamethoxazole were partly degraded in the studied WWTP. Furthermore, levofloxacin and ciprofloxacin are the only antibiotics under investigation with a significant mass fraction bound to primary, excess and digested sludge. Nevertheless, the sludge concentrations are highly inconsistent which leads to questionable results. It remains unclear whether the inconsistencies are due to insufficiencies in sampling and/or analytical determination or if the fluctuations can be considered reasonable for digesters. Hence, future investigations have to address antibiotic's temporal dynamics during the sludge treatment to decide whether or not the widely reported standard deviations of sludge concentrations reflect realistic fluctuations.

A review on emerging contaminants in wastewaters and the environment: current knowledge, understudied areas and recommendations for future monitoring

This review identifies understudied areas of emerging contaminant (EC) research in wastewaters and the environment, and recommends direction for future monitoring. Non-regulated trace organic ECs including pharmaceuticals, illicit drugs and personal care products are focused on due to ongoing policy initiatives and the expectant broadening of environmental legislation. These ECs are ubiquitous in the aquatic environment, mainly derived from the discharge of municipal wastewater effluents. Their presence is of concern due to the possible ecological impact (e.g., endocrine disruption) to biota within the environment. To better understand their fate in wastewaters and in the environment, a standardised approach to sampling is needed. This ensures representative data is attained and facilitates a better understanding of spatial and temporal trends of EC occurrence. During wastewater treatment, there is a lack of suspended particulate matter analysis due to further preparation requirements and a lack of good analytical approaches. This results in the under-reporting of several ECs entering wastewater treatment works (WwTWs) and the aquatic environment. Also, sludge can act as a concentrating medium for some chemicals during wastewater treatment. The majority of treated sludge is applied directly to agricultural land without analysis for ECs. As a result there is a paucity of information on the fate of ECs in soils and consequently, there has been no driver to investigate the toxicity to exposed terrestrial organisms. Therefore a more holistic approach to environmental monitoring is required, such that the fate and impact of ECs in all exposed environmental compartments are studied. The traditional analytical approach of applying targeted screening with low resolution mass spectrometry (e.g., triple quadrupoles) results in numerous chemicals such as transformation products going undetected. These can exhibit similar toxicity to the parent EC, demonstrating the necessity of using an integrated analytical approach which compliments targeted and non-targeted screening with biological assays to measure ecological impact. With respect to current toxicity testing protocols, failure to consider the enantiomeric distribution of chiral compounds found in the environment, and the possible toxicological differences between enantiomers is concerning. Such information is essential for the development of more accurate environmental risk assessment.

Occurrence and removal of transformation products of PPCPs and illicit drugs in wastewaters: a review

Pharmaceuticals and personal care products (PPCPs) along with illicit drugs (IDs) are newly recognized classes of environmental pollutants and are receiving considerable attention because of their environmental impacts: frequent occurrence, persistence and risk to aquatic life and humans. However, relatively little information is often available with regard to their possible biotic and abiotic transformation products (TPs). This lack of knowledge has resulted in a substantial amount of ongoing effort to develop methods and approaches that would assess their occurrence, degradability potential elimination mechanisms and efficiencies in sewage treatment plants as well as environmental and human health risks. In this article, an extensive literature survey was performed in order to present the current stage of knowledge and progress made in the occurrence of TPs of PPCPs and IDs in raw and treated wastewaters. Apart from the TPs resulting from structural transformations of the parent compound in the aquatic environment or in technological treatment facilities (e.g. sewage and drinking water treatment plants), free metabolites and drug conjugates formed during human metabolism have also been included in this review as they are also released into the aquatic environment through wastewaters. Their concentration levels were reported in influents and effluents of WWTPs, hospital effluents and their removals in the treatment plants were discussed. Finally, information on the toxicity of TPs has been compiled when available.