Occurrence of pharmaceuticals and endocrine disruptors in raw sewage and their behavior in UASB reactors operated at different hydraulic retention times

Anaerobic removal of contaminants of emerging concern in municipal wastewater: Eco-toxicological risk evaluation and strategic selection of optimal treatment

In the last decades, the interest for anaerobic process as a mainstream treatment of municipal wastewater increased due to the development of high-rate anaerobic bioreactors able to achieve removal kinetics comparable to the aerobic ones. Moreover, they have the additional advantages of energy production, nutrient recovery and reduced excess sludge yield, which are interesting features in the frame of sustainability wastewater treatment goals. These appealing factors increased the research demand to evaluate the potential of the anaerobic removal for contaminants of emerging concern (CECs) in municipal wastewater. However, despite the growing interest for the subject, literature is still fragmentary and reviews are mainly focused on specific technologies and target compounds or groups of compounds. We propose this review with the main objectives of presenting the state of knowledge, the performances of anaerobic systems for CECs' removal and, more important, to give the reader guidelines for optimal treatment selection. In the first part, a general overview of the investigated technologies at different scale, with a special focus on the recently proposed enhancements, is presented. Collected data are analysed to select the target CECs and the analysis results employed to define the optimal technological solution for their removal. A first novelty element of the paper is the original procedure for contaminant selection consisting of a risk assessment tool for CECs, based on their frequency of detection, concentration and potential for biosorption in wastewater treatment plants. Data of selected target CECs are combined with compound and technology performance data to implement a flowchart tool to evaluate the optimal treatment strategy, which constitute another, even more important, novelty element of this study.

Predicting and improving the microbial removal of organic micropollutants during wastewater treatment: A review

Organic micropollutants (OMPs) consist of widely used chemicals such as pharmaceuticals and pesticides that can persist in surface and groundwaters at low concentrations (ng/L to μg/L) for a long time. The presence of OMPs in water can disrupt aquatic ecosystems and threaten the quality of drinking water sources. Wastewater treatment plants (WWTPs) rely on microorganisms to remove major nutrients from water, but their effectiveness at removing OMPs varies. Low removal efficiency might be the result of low concentrations, inherent stable chemical structures of OMPs, or suboptimal conditions in WWTPs. In this review, we discuss these factors, with special emphasis on the ongoing adaptation of microorganisms to degrade OMPs. Finally, recommendations are drawn to improve the prediction of OMP removal in WWTPs and to optimize the design of new microbial treatment strategies. OMP removal seems to be concentration-, compound-, and process-dependent, which poses a great complexity to develop accurate prediction models and effective microbial processes targeting all OMPs.

Environmental risk caused by drug waste in the city of Rio de Janeiro, Brazil, during the SARS-Cov19 pandemic

Abstract The relationship between the distribution of medicines used in the Pandemic by SARS-COV-19 in the municipality of Rio de Janeiro and the estimated level of environmental risk caused by their residues was evaluated. The amount of medicines distributed by primary health care (PHC) units between 2019 and 2021 were collected. The risk quotient (RQ) corresponded to the ratio between the estimated predictive environmental concentration (PECest) obtained by the consumption and excretion of each drug and its non-effective predictive concentration (PNEC). Between 2019 and 2020, the PECest of azithromycin (AZI) and ivermectin (IVE) increased between 2019 and 2020, with a decrease in 2021 probably due to shortages. Dexchlorpheniramine (DEX) and fluoxetine (FLU) fell, returning to growth in 2021. While the PECest of diazepam (DIA) increased over these 3 years, ethinylestradiol (EE2) decreased possibly due to the prioritization of PHC in the treatment of COVID-19. The largest QR were from FLU, EE2 and AZI. The consumption pattern of these drugs did not reflect their environmental risk because the most consumed ones have low toxicity. It is worth noting that some data may be underestimated due to the incentive given during the pandemic to the consumption of certain groups of drugs.

Environmental risk caused by drug waste in the city of Rio de Janeiro, Brazil, during the SARS-Cov19 pandemic

The relationship between the distribution of medicines used in the Pandemic by SARS-COV-19 in the municipality of Rio de Janeiro and the estimated level of environmental risk caused by their residues was evaluated. The amount of medicines distributed by primary health care (PHC) units between 2019 and 2021 were collected. The risk quotient (RQ) corresponded to the ratio between the estimated predictive environmental concentration (PECest) obtained by the consumption and excretion of each drug and its non-effective predictive concentration (PNEC). Between 2019 and 2020, the PECest of azithromycin (AZI) and ivermectin (IVE) increased between 2019 and 2020, with a decrease in 2021 probably due to shortages. Dexchlorpheniramine (DEX) and fluoxetine (FLU) fell, returning to growth in 2021. While the PECest of diazepam (DIA) increased over these 3 years, ethinylestradiol (EE2) decreased possibly due to the prioritization of PHC in the treatment of COVID-19. The largest QR were from FLU, EE2 and AZI. The consumption pattern of these drugs did not reflect their environmental risk because the most consumed ones have low toxicity. It is worth noting that some data may be underestimated due to the incentive given during the pandemic to the consumption of certain groups of drugs.

Challenges on solar oxidation as post-treatment of municipal wastewater from UASB systems: Treatment efficiency, disinfection and toxicity

The application of solar photo-Fenton as post-treatment of municipal secondary effluents (MSE) in developing tropical countries is the main topic of this review. Alternative technologies such as stabilization ponds and upflow anaerobic sludge blanket (UASB) are vastly applied in these countries. However, data related to the application of solar photo-Fenton to improve the quality of effluents from UASB systems are scarce. This review gathered main achievements and limitations associated to the application of solar photo-Fenton at neutral pH and at pilot scale to analyze possible challenges associated to its application as post-treatment of MSE generated by alternative treatments. To this end, the literature review considered studies published in the last decade focusing on CECs removal, toxicity reduction and disinfection via solar photo-Fenton. Physicochemical characteristics of effluents originated after UASB systems alone and followed by a biological post-treatment show significant difference when compared with effluents from conventional activated sludge (CAS) systems. Results obtained for solar photo-Fenton as post-treatment of MSE in developed countries indicate that remaining organic matter and alkalinity present in UASB effluents may pose challenges to the performance of solar advanced oxidation processes (AOPs). This drawback could result in a more toxic effluent. The use of chelating agents such as Fe³⁺-EDDS to perform solar photo-Fenton at neutral pH was compared to the application of intermittent additions of Fe²⁺ and both of these strategies were reported as effective to remove CECs from MSE. The latter strategy may be of greater interest in developing countries due to costs associated to complexing agents. In addition, more studies are needed to confirm the efficiency of solar photo-Fenton on the disinfection of effluent from UASB systems to verify reuse possibilities. Finally, future research urges to evaluate the efficiency of solar photo-Fenton at natural pH for the treatment of effluents from UASB systems.

Removal of micropollutants by UASB reactor and post-treatment by Fenton and photo-Fenton: Matrix effect and toxicity responses

Literature is scarce on the performance of Fenton-based processes as post-treatment of municipal wastewater treated by upflow anaerobic sludge blanket (UASB) reactor. This study aims to perform Fenton and photo-Fenton from UASB influent and effluent matrices to remove micropollutants (MPs) models: atrazine (ATZ), rifampicin (RIF), and 17α-ethynylestradiol (EE2). A UASB reactor at bench-scale (14 L) was operated with these MPs, and the AOPs experiments at bench-scale were performed on a conventional photochemical reactor (1 L). A high-pressure vapor mercury lamp was used for photo-Fenton process (UVA-Vis) as a radiation source. Microcrustacean Daphnia magna (acute toxicity) and seeds of Lactuca sativa (phytotoxicity) were indicator organisms for toxicity monitoring. The UASB reactor showed stability removing 90% of the mean chemical oxygen demand, and removal efficiencies for ATZ, RIF, and EE2 were 16.5%, 45.9%, and 15.7%, respectively. A matrix effect was noted regarding the application of both Fenton and photo-Fenton in UASB influent and effluent to remove MPs and toxicity responses. The pesticide ATZ was the most recalcitrant compound, yet the processes carried out from UASB effluent achieved removal >99.99%. The post-treatment of the UASB reactor by photo-Fenton removed acute toxicity in D. magna for all treatment times. However, only the photo-Fenton conducted for 90 min did not result in a phytotoxic effect in L. sativa.

A review toward contaminants of emerging concern in Brazil: Occurrence, impact and their degradation by advanced oxidation process in aquatic matrices

This work presents data regarding the occurrence and treatment of Contaminants of Emerging Concern (CECs) in Brazil in the past decade. The literature review (2011-2021) revealed the detection of 87 pharmaceutical drugs and personal care products, 58 pesticides, 8 hormones, 2 illicit drugs, caffeine and bisphenol A in distinct matrices (i.e.: wastewater, groundwater, sea water, rainwater, surface water, drinking water and hospital effluent). Concentrations of CECs varied from ng-μg L^-1 depending on the location, compound and matrix. The inefficiency of conventional wastewater treatment methods on the removal of CECs and lack of basic sanitation in some regions in the country aggravates contamination of Brazilian aquatic environments and poses potential environmental and health risks. Advanced oxidation processes (AOPs) are pointed out as viable and efficient alternatives to degrade CECs and prevent environmental contamination. A total of 375 studies involving the use of AOPs in Brazilian aqueous matrices were published in the last decade. Fenton and photo-Fenton processes, photo-peroxidation, ozonation, electrochemical advanced oxidation and heterogeneous photocatalysis are some of the AOPs applied by Brazilian research groups. Although many works discuss the importance of applying these technologies for CECs removal in real treatment plants, most of these studies assess the treatment of distilled water or simulated effluent. Therefore, the conduction of studies applying AOPs in real matrices are critical to drive the implementation of these processes coupled to conventional water and wastewater treatment in real plants in order to prevent the contamination of environmental matrices by CECs in Brazil.

17α-ethynylestradiol and its two main conjugates in seven municipal wastewater treatment plants: Analytical method, their occurrence, removal and risk evaluation

This work shows the existence of both 17-ethinylestradiol-3-sulfate (EE2-3S) and 17-ethinylestradiol-3-glucuronide (EE2-3G) in seven municipal WWTPs with substantial concentrations (n.d-50.10 ng/L). The calculated removal efficiencies of 17-ethinylestradiol (EE2) in the seven municipal WWTPs ranged from 40.8%-100% with an average removal efficiency of 83.3%. However, upon the inclusion of EE2 concentration transformed from EE2-3S and EE2-3G, the corresponding removal efficiencies were increased to 91.4%-100% with an average removal efficiency of 97.3%. This work is the first to clearly illustrate that EE2 conjugates in raw wastewater could greatly underestimate the removal effectiveness of municipal WWTPs on EE2, indicating the importance of the EE2 conjugates in municipal wastewater having been hardly paid with attention. The EE2-derived estrogen equivalence (EEQ) values in the effluents of seven WWTPs ranged from 0 to 0.98 ng E2/L having an average level of 0.45 ng E2/L, which were relatively low. However, upon the inclusion of EE2 transformable from EE2-3S and EE2-3G in effluents, the EE2-derived EEQ values in effluents would be increased to 0.77-4.85 ng E2/L having an average level of 2.71 ng E2/L, which clearly suggested that ignorance of EE2 conjugates in effluent would largely underestimate EE2's environmental risk to receiving water bodies.

Removal of 17α-ethinylestradiol and caffeine from wastewater by UASB-Fenton coupled system

In aquatic systems, some substances considered as endocrine disruptors have been detected, which can be due to their incomplete elimination in wastewater treatment plants (WWTPs) and inadequate disposal of pharmaceuticals. Among these contaminants are 17α-ethinylestradiol (EE2) and caffeine (CAF). Moreover, it has been reported that this kind of contaminants may provoke different adverse effects in many aquatic organisms. Because of that, in the present study, up-flow anaerobic sludge blanket reactors (UASB) coupled with the Fenton process was evaluated for EE2 and CAF removal spiked in wastewater samples. First, the best reaction conditions were established in each process. For UASB reactor, two hydraulic retention times (HRT 8 and 24 h) were evaluated, achieving the highest chemical organic demand (COD) removal (70 %) and drug elimination (84 %-86 %) with HRT 24 h. Subsequently, Fenton process was conducted at pH 3 with different levels of Fe²⁺ (0.05-0.5 mmol/L) and molar ratios Fe²⁺:H₂O₂ (1:1-1:10). Better results were obtained with 0.5 mmol Fe²⁺/L, and 1:10 ratio molar Fe²⁺:H₂O₂. Finally, UASB-Fenton coupled system allowed 80 % of COD decrease, almost complete removal of drugs and the toxicity of samples on Vibrio fischeri was reduced from 73 % to 30 %, demonstrating that this coupled system is a promising and efficient system for pharmaceutical compounds removal from wastewater.

Effect of concentration and hydraulic reaction time on the removal of pharmaceutical compounds in a membrane bioreactor inoculated with activated sludge

Pharmaceuticals are often not fully removed in wastewater treatment plants (WWTPs) and are thus being detected at trace levels in water bodies all over the world posing a risk to numerous organisms. These organic micropollutants (OMPs) reach WWTPs at concentrations sometimes too low to serve as growth substrate for microorganisms; thus, co-metabolism is thought to be the main conversion mechanism. In this study, the microbial removal of six pharmaceuticals was investigated in a membrane bioreactor at increasing concentrations (4-800 nM) of the compounds and using three different hydraulic retention times (HRT; 1, 3.5 and 5 days). The bioreactor was inoculated with activated sludge from a municipal WWTP and fed with ammonium, acetate and methanol as main growth substrates to mimic co-metabolism. Each pharmaceutical had a different average removal efficiency: acetaminophen (100%) > fluoxetine (50%) > metoprolol (25%) > diclofenac (20%) > metformin (15%) > carbamazepine (10%). Higher pharmaceutical influent concentrations proportionally increased the removal rate of each compound, but surprisingly not the removal percentage. Furthermore, only metformin removal improved to 80-100% when HRT or biomass concentration was increased. Microbial community changes were followed with 16S rRNA gene amplicon sequencing in response to the increment of pharmaceutical concentration: Nitrospirae and Planctomycetes 16S rRNA relative gene abundance decreased, whereas Acidobacteria and Bacteroidetes increased. Remarkably, the Dokdonella genus, previously implicated in acetaminophen metabolism, showed a 30-fold increase in abundance at the highest concentration of pharmaceuticals applied. Taken together, these results suggest that the incomplete removal of most pharmaceutical compounds in WWTPs is dependent on neither concentration nor reaction time. Accordingly, we propose a chemical equilibrium or a growth substrate limitation as the responsible mechanisms of the incomplete removal. Finally, Dokdonella could be the main acetaminophen degrader under activated sludge conditions, and non-antibiotic pharmaceuticals might still be toxic to relevant WWTP bacteria.

Occurrence and removal of micropollutants in full-scale aerobic, anaerobic and facultative wastewater treatment plants in Brazil

This study aims to evaluate micropollutant occurrence and removal in a low-middle income country (LMIC) by investigating the occurrence of 28 chemicals from different classes (triclosan, 15 polycyclic aromatic hydrocarbons (PAHs), 4 estrogens and 8 polybrominated diphenyl ether (PBDE) congeners) in three technologically diverse full-scale Brazilian wastewater treatment plants (WWTPs). These chemicals were detected at concentrations similar to those reported in other low-middle income countries (LMICs) and high-income countries (HICs) (0.1-49 μg/L) indicating their widespread use globally and the need for more studies in LMICs that are typically characterized by relatively inadequate wastewater treatment barriers. Among the three different WWTPs investigated for removal of these chemicals, the least energy intensive system, waste stabilization ponds (WSPs), was the most effective (95-99%) compared to the activated sludge (79-94%), and Up-flow sludge blanket reactor (UASB) with trickling filters system (89-95%). These results highlight the potential of WSPs for micropollutant removal-especially in warm climates. However, the effluent from all three WWTP could pose a risk to aquatic organisms when discharged into the receiving waters as the effluent concentrations of triclosan, some estrogens, PAHs and BDE 209 were above European environmental quality standards (EQS) or predicted no effect concentration (PNEC values), indicating that receiving water bodies could benefit from further treatment. In combination, these results help to further understand prevailing concentrations of micropollutants globally and fate in current wastewater treatment systems.

Pharmaceutical Pollution and Disposal of Expired, Unused, and Unwanted Medicines in the Brazilian Context

The occurrence of pharmaceuticals in the environment is an everyday recognized concern worldwide, and drugs as environmental contaminants have been detected in water and soil systems, posing risks to humans and wildlife. The presence of drugs in wastewater, groundwater, and even drinking water occurs in several countries, including Brazil, where the pharmaceutical market is expanding over the years. The adverse, harmful effects of pharmaceuticals in the environment range from the spreading of antimicrobial resistance and species survival to the interference with reproduction and increased cancer incidence in humans. Therefore, it is demanding to count on proper legislation to prevent these pollutants from entering the distinct environment compartments. In some developed countries, laws, directives, programs, and initiatives regarding drug disposal reach a mature status. In Brazil, federal laws dealing with drug residues' management are recent, with flaws that might facilitate non-compliance with drug pollution issues. Besides, pharmacies and drugstores are not obligated to collect unneeded household medicines, while particular State laws aim to ordinate the disposal of drug residues regionally. In this review, we consider the current knowledge about pharmaceutical (drug) pollution, the recommendation and regulations on the disposal of useless medicines in some countries, and in the context of the expanding pharmaceutical market in Brazil. The awareness of emerging contaminants in the environment, besides the joint effort of authorities, consumers, and the general public nationwide, will be required to avoid pharmaceutical/drug pollution and achieve an eco-friendly environment and a sustainable society.

Integration of ozonation and an anaerobic expanded granular sludge bed reactor for micropollutant removal from sewage

Conventional sewage treatment systems are generally not designed to remove micropollutants, requiring the development of new technologies, such as the combination of biological processes with advanced oxidative processes. The configuration of an anaerobic expanded granular sludge bed (EGSB) reactor stands out for its use of granular biomass and high sludge bed expansion. Ozonation is an advanced oxidative process that stands out as one of the most promising technologies for the degradation of micropollutants. Thus, the present work aimed to evaluate the removal of drugs through the application of ozonation as a polishing process for the effluent of an EGSB reactor that was fed with synthetic sewage. Ozonation was shown to be efficient in the degradation of these compounds, reaching removals above 90%. It was found that the degradation profile of each drug varied according to its chemical structure since some drugs are more susceptible to oxidation than others and since the concentrations of pharmaceuticals are also related to their removal. Moreover, the assessment of risks to the environment and human health confirmed the need to assess the best scenario for risk reduction considering all drugs, since even with almost complete removal of some compounds, the effluents still showed toxicity. Thus, the high removal efficiencies found for the evaluated micropollutants showed that this technique has the potential to be used to improve the quality of biological reactor effluents or even to be combined in effluent reuse systems.

Evaluation of toxicity and estrogenicity in UASB - Treated municipal sewage

This study was undertaken to assess the capacity of the upflow anaerobic sludge blanket (UASB) reactor, one of the most commonly used systems in Brazilian sewage treatment plants, to remove municipal sewage toxicity using different Danio rerio life stages (embryo, embryo-larval, larval, adult), and estrogenicity using in vitro (yeast Saccharomyces cerevisiae) and in vivo (vitellogenin induction in D. rerio) assays. Sensitivity of chronic fish assays were compared to the chronic Ceriodaphnia dubia assay. UASB-treated sewage met Brazilian legal limits for BOD and COD removals, but did not remove toxicity, and treated sewage remained extremely toxic to D. rerio larvae and C. dubia, and highly toxic to D. rerio embryos. The 4-day embryo assay had the same sensitivity as the adult acute toxicity assay, and could safely replace it, avoiding the need to sacrifice adult fish. No significant differences were identified in vitellogenin induction among organisms exposed to sewage or control. However, the in vitro test showed that anaerobic treatment increased sample estrogenicity from 27 to 40 ng equivalents of 17-β estradiol per liter, a result corroborated by the greater induction of vitellogenin in male fish exposed to 5% (2.73 μg/g) and 20% (2.12 μg/g) treated sewage compared to the same concentrations of raw sewage (0.174 μg/g at 5% and 0.188 μg/g at 20%). Thus, UASB reactor should be followed by post-treatment to reduce risks of sewage discharge to receiving waters.

Anaerobic Transformation and Detoxification of Sulfamethoxazole by Sulfate-Reducing Enrichments and Desulfovibrio vulgaris

Sulfamethoxazole (SMX) is a veterinary antibiotic that is not efficiently removed from wastewater by routine treatment and therefore can be detected widely in the environment. Here, we investigated whether microbial anaerobic transformation can contribute to the removal of SMX in constructed systems. We enriched SMX-transforming mixed cultures from sediment of a constructed wetland and from digester sludge of a wastewater treatment plant. Transformation of SMX was observed in both sulfate-reducing and methanogenic cultures, whereas nitrate-reducing cultures showed no SMX transformation. In sulfate-reducing cultures, up to 90% of an initial SMX concentration of 100-250 μM was removed within 6 weeks of incubation, and the experiments demonstrated that the transformation was microbially catalyzed. The transformation products in sulfate-reducing cultures were identified as the reduced and isomerized forms of the isoxazole SMX moiety. The transformation products did not spontaneously reoxidize to SMX after oxygen exposure, and their antibacterial activity was significantly decreased compared to SMX. Population analyses in sequential transfers of the sulfate-reducing cultures revealed a community shift toward the genus Desulfovibrio. We therefore tested a deposited strain of Desulfovibrio vulgaris Hildenborough for its capacity to transform SMX and observed the same transformation products and similar transformation rates as in the enrichment cultures. Our work suggests that an initial anaerobic step in wastewater treatment can reduce the concentration of SMX in effluents and could contribute to decreased SMX concentrations in the environment.

Comparative endocrine disrupting compound removal from real wastewater by UV/Cl and UV/H2O2: Effect of pH, estrogenic activity, transformation products and toxicity

Extensive use of endocrine disruptor compounds (EDCs) and their release through various pathways into the environment are emerging environmental concerns. In this context, H₂O₂ and chlorine UV-based treatments were carried out to evaluate their efficiency in the removal of the bisphenol A (BPA), 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) at 100 μg L^-1 from ultrapure water and from wastewater treatment plants (WWTP). Photolysis was performed under different irradiation sources, i.e. UVC and UVA. The effect of H₂O₂ (3 and 30 mg·L^-1), free chlorine concentrations (1 and 2 mg·L^-1) and pH (5, 7 and 9) were also investigated. Toxicity (Raphidocelis subcapitata) and estrogenic activity (yeast estrogen screen - YES assay) were assessed during the processes. Compound removal at optimal operating parameters reached 100% after 15 and 2 min for UVC/H₂O₂ (pH 9 and 3 mg L^-1 of H₂O₂), and UVC/Cl (pH 9 and 2 mg L^-1 of chlorine), respectively. Total organic carbon (TOC) removal achieved 37% and 45% for the H₂O₂ and Cl-UV based process, respectively. The in vitro YES assay indicated that the formed by-products were non-estrogenic compounds, while the toxicity evaluation revealed high cell growth inhibition due to UVC/Cl byproducts. During the UV-based processes, 30 transformation products (TPs) were identified, in which three new chlorinated TPs from E2 and EE2 may be responsible for toxicity effects. EDC degradation by UV/Cl is faster than by UV/H₂O₂, although chlorinated toxic byproducts were also formed during the UV/Cl process.

Can high rate algal ponds be used as post-treatment of UASB reactors to remove micropollutants?

The present study evaluated the removal capacity of a UASB-HRAP treatment system, combining anaerobic and microalgae-based, aerobic treatment, for eleven organic micropollutants present in raw sewage, including pharmaceuticals, estrogens and xenoestrogens. The UASB reactor and the HRAP were operated at a hydraulic retention time (HRT) of 7 h and 8 days, respectively. Influent and effluent samples from the UASB and HRAP were collected periodically. All the target compounds were detected in raw sewage, with an occurrence ranging from 70 to 100%. Removal rates in the UASB reactor were generally incomplete, ranging from no removal (-25.12% for the hormone EE2-ethinylestradiol) to 84.91% (E2 - estradiol). However, the overall performance of the UASB + HRAP system was highly efficient for the majority of the compounds, with removal rates ranging from 64.8% (ibuprofen) to 95% (estrone). Gemfibrozil and bisphenol A were the only exceptions, with overall removal rates of 39% and 43%, respectively. Hormones were the compounds with the highest removal rates in the system.

Emerging pollutants in the urban water cycle in Latin America: A review of the current literature

Emerging pollutants (EP) are increasingly studied and characterized worldwide to improve the understanding of their environmental and toxicological impacts and their occurrence and behaviors in different environmental systems. Latin America has been subject to both environmental and toxicological impacts due to EP. To better understand these impacts, studies concerning pollutants have increased for the last ten years. The current study presents a critical review on the occurrence of different emerging pollutants in various components of the urban water cycle (UWC) in Latin America. The review is based on studies performed in 11 different countries between 1999 and 2018. The countries where the higher number of investigations were conducted are Brazil (53%) and Mexico (15%). The EP most often studied within the literature are pharmaceuticals, followed by personal care products. The most common EP reported were 17β-estradiol, bisphenol A and estrone; The UWC component with the greatest number of measurements in the reported studies were effluents from wastewater treatment plants.

Simultaneous and efficient photocatalytic reduction of Cr(VI) and oxidation of trace sulfamethoxazole under LED light by rGO@Cu2O/BiVO4p-n heterojunction composite

Antibiotics and heavy metals often coexist in polluted environment, and the harm of combined pollution is greater than that of single pollution. In this study, a series of graphene supported p-n heterojunction rGO@Cu₂O/BiVO₄ composites are synthesized with different Cu₂O doping for simultaneous detoxification of Cr(VI) and antibiotics. The obtained photocatalysts (rGO@Cu₂O/BiVO₄) with proper loading amount of Cu₂O shows the a high photocatalytic degradation activity for simultaneously efficient Cr(VI) reduction and sulfamethoxazole (SMZ) oxidation under LED light at neutral pH. The Cr(VI) was completely transformed to Cr(III) rather than simply Cr(VI) adsorbed on the surface of rGO@Cu₂O/BiVO₄. The photocatalytic activity of composites can be attributed to excellent electrical conductivity of rGO and the p-n heterojunction between Cu₂O and BiVO₄, which promotes the spatial separation of photogenerated charges at the heterojunction boundary and inhibits of the photogenerated h⁺ and e^- recombination. It's confirmed that h⁺, O₂^- and OH are the main reactive species for the photocatalytic SMZ oxidation, and the most important reactive species is h⁺. Finally, the tentative degradation pathways of SMZ are proposed based on the liquid chromatography-triple quadrupole mass spectrometry analysis. This work provides an effective approach for the treatment of water that contains SMZ and Cr(VI) under LED light.

Removal kinetics of sulfamethazine and its transformation products formed during treatment using a horizontal flow-anaerobic immobilized biomass bioreactor

Sulfamethazine (SMZ) is an antibiotic from sulfonamides class widely used in veterinary medicine and reported in wastewater and sewage. Thus, it is essential to study technologies to reduce SMZ present in the aquatic environment. Anaerobic bioreactors are a low-cost technology applied for wastewater treatment. The objective of this paper is to study kinetics parameters related to SMZ removal using a horizontal flow-anaerobic immobilized biomass reactor (HAIB) and to evaluate its transformation products formed during this treatment. The bioreactor was operated at mesophilic condition with a hydraulic retention time of 12 h. The removal of SMZ was evaluated at three different concentrations: 200 ng L^-1 (phase I), 400 ng l^-1 (phase II) and 600 ng L^-1 (phase III). The apparent first-order removal constant obtained for chemical oxygen demand was 0.885 ± 0.094 h^-1 while SMZ showed a removal constant of 0.356 h^-1. SMZ was removed with an efficiency of 56.0 ± 13.0 % (phase I); 62.0 ± 12.0 % (phase II) and 62.0 ± 6.00 % (phase III). Seven transformation products were detected and one of these with m/z 233 is reported for the first-time. The HAIB bioreactor has a potential to assist in wastewater treatment to remove contaminants at ng L^-1 concentration level.

Evaluation of sulfamethazine removal kinetics using fixed structured bed bioreactor

The use of anaerobic biomass attached to a support has been recently presented as a good prospect in the treatment of wastewater containing recalcitrant compounds, such as sulfamethazine (SMZ). SMZ has been found in swine wastewater and sewage treatment plants, which motivates assessing their degradation by new wastewater treatment technologies. Thus, this paper describes the use of a continuous fixed structured bed bioreactor for the purpose of evaluating SMZ removal kinetics present in lab-made wastewater. The analysis of SMZ used online solid-phase extraction coupled to liquid chromatography/tandem mass spectrometry (SPE online-LC-MS/MS). Chemical oxygen demand (COD) was also monitored to evaluate the organic matter removal. The bioreactor was operated under mesophilic conditions (30 ∘ C), with a hydraulic retention time of 24 h. In order to evaluate SMZ removal, four different concentration levels were studied: 200, 400, 600, and 800 ng L^-1. COD removal efficiency obtained for filtered effluent kept at 91.01% and there was no interference due to the increase of SMZ concentration. For SMZ, the removal efficiencies were of 52.8±12.1% for 200 ng L^-1 concentration level; 55.0±8.15% for 400 ng L^-1; 53.0±6.14% for 600 ng L^-1, and 48.8±5.44% for 800 ng L^-1. COD removal kinetics presented a first-order apparent removal rate constant ( kapp ) of 0.281±0.0295  h^-1. SMZ also showed a first-order apparent removal rate constant of 0.158±0.0093  h^-1 for the following concentrations levels: 200, 400, 600, and 800 ng L^-1.

The contribution of selected organic substrates to the anaerobic cometabolism of sulfamethazine

Biodegradation of organic micropollutants is likely to occur due to cometabolism by particular microbial groups. In an effort to identify the stages of anaerobic digestion potentially involved in the biodegradation of the veterinary antimicrobial sulfamethazine (SMZ), the influence of selected carbon sources (sucrose, glucose, fructose, ethanol, meat extract, cellulose, soluble starch, soy oil, acetic acid, propionic acid and butyric acid) on SMZ removal by anaerobic sludge was evaluated in short-term batch experiments. Adsorption to the granular sludge constituted a significant removal mechanism, accounting for 39% of SMZ removal in control experiments. The presence of glucose, fructose, sucrose and meat extract exerted an inducing effect on SMZ degradation, resulting in removal efficiencies of 54, 53, 58 and 61%, respectively, indicating the occurrence of cometabolism. Time courses of sucrose and meat extract degradation revealed markedly distinct organic acid profiles but resulted in similar SMZ removals. Temporal profiles of acetic and propionic acid degradation were not associated with SMZ removal, as changes in SMZ concentration were observed even after the organic acids had been completely removed. The experimental results suggest that SMZ cometabolism is not associated to sucrose hydrolysis, acetoclastic methanogenesis and acetogenesis from propionic acid.

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.

Micropollutant removal from black water and grey water sludge in a UASB-GAC reactor

The effect of granular activated carbon (GAC) addition on the removal of diclofenac, ibuprofen, metoprolol, galaxolide and triclosan in a up-flow anaerobic sludge blanket (UASB) reactor was studied. Prior to the reactor studies, batch experiments indicated that addition of activated carbon to UASB sludge can decrease micropollutant concentrations in both liquid phase and sludge. In continuous experiments, two UASB reactors were operated for 260 days at an HRT of 20 days, using a mixture of source separated black water and sludge from aerobic grey water treatment as influent. GAC (5.7 g per liter of reactor volume) was added to one of the reactors on day 138. No significant difference in COD removal and biogas production between reactors with and without GAC addition was observed. In the presence of GAC, fewer micropollutants were washed out with the effluent and a lower accumulation of micropollutants in sludge and particulate organic matter occurred, which is an advantage in micropollutant emission reduction from wastewater. However, the removal of micropollutants by adding GAC to a UASB reactor would require more activated carbon compared to effluent post-treatment. Additional research is needed to estimate the effect of bioregeneration on the lifetime of activated carbon in a UASB-GAC reactor.

Removal of the veterinary antimicrobial sulfamethazine in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor subjected to step changes in the applied organic loading rate

A bench-scale horizontal-flow anaerobic immobilized biomass (HAIB) reactor treating synthetic swine wastewater was operated under different applied organic loading rates (OLR) through both variations in feed strength and in hydraulic retention time (HRT). The influence of step changes in OLR on the removal of the veterinary antimicrobial sulfamethazine (SMZ) was assessed. The highest observed SMZ removal efficiency, 75 ± 6%, was achieved with an OLR of 2.7 ± 0.4 kg O₂ m^-3 d^-1 when a significant increase in COD removal rate was observed. The SMZ removal rate was positively correlated (r = 0.899) to the COD removal rate in all of the experimental conditions in which the HRT was kept at 24 h, indicating a cometabolic transformation of the antimicrobial. Decreasing the HRT caused a significant decrease in SMZ removal efficiency without affecting the HAIB reactor performance in terms of stability, COD removal or metabolic intermediates production. Functionally equivalent steady states were observed in four different operational phases with similar operating conditions but with widely different behavior in relation to SMZ removal. The experimental results showed the potential of anaerobic technology in removing environmentally relevant concentrations of SMZ, and the possibility of enhancing reactor performance by controlling operating conditions.

Fate of pharmaceuticals in full-scale source separated sanitation system

Removal of 14 pharmaceuticals and 3 of their transformation products was studied in a full-scale source separated sanitation system with separate collection and treatment of black water and grey water. Black water is treated in an up-flow anaerobic sludge blanket (UASB) reactor followed by oxygen-limited autotrophic nitrification-denitrification in a rotating biological contactor and struvite precipitation. Grey water is treated in an aerobic activated sludge process. Concentration of 10 pharmaceuticals and 2 transformation products in black water ranged between low μg/l to low mg/l. Additionally, 5 pharmaceuticals were also present in grey water in low μg/l range. Pharmaceutical influent loads were distributed over two streams, i.e. diclofenac was present for 70% in grey water, while the other compounds were predominantly associated to black water. Removal in the UASB reactor fed with black water exceeded 70% for 9 pharmaceuticals out of the 12 detected, with only two pharmaceuticals removed by sorption to sludge. Ibuprofen and the transformation product of naproxen, desmethylnaproxen, were removed in the rotating biological contactor. In contrast, only paracetamol removal exceeded 90% in the grey water treatment system while removal of other 7 pharmaceuticals was below 40% or even negative. The efficiency of pharmaceutical removal in the source separated sanitation system was compared with removal in the conventional sewage treatment plants. Furthermore, effluent concentrations of black water and grey water treatment systems were compared with predicted no-effect concentrations to assess toxicity of the effluent. Concentrations of diclofenac, ibuprofen and oxazepam in both effluents were higher than predicted no-effect concentrations, indicating the necessity of post-treatment. Ciprofloxacin, metoprolol and propranolol were found in UASB sludge in μg/g range, while pharmaceutical concentrations in struvite did not exceed the detection limits.

Rapid determination of 12 antibiotics and caffeine in sewage and bioreactor effluent by online column-switching liquid chromatography/tandem mass spectrometry

This study presents a column-switching solid-phase extraction online-coupled to a liquid chromatography/tandem mass spectrometry (SPE-LC-MS/MS) method for simultaneous analysis of 12 antibiotics (7 sulfonamides and 5 fluoroquinolones) and caffeine detected in the sewage and effluent of a pilot anaerobic reactor used in sewage treatment. After acidification and filtration, the samples were directly injected into a simple and conventional LC system. Backflush and foreflush modes were compared based on the theoretical plates and peak asymmetry observed. The method was tested in terms of detection (MDL) and quantification limit (MQL), linearity, relative recovery, and precision intra- and inter-day in lab-made sewage samples. The method presented suitable figures of merit in terms of detection, varying from 8.00 × 10(-5) to 6.00 × 10(-2) ng (0.800 up to 600 ng L(-1); caffeine) with direct injection volume of only 100 μL and 13 min of total analysis time (sample preparation and chromatographic run). When the method was applied in the analysis of sewage and effluent of the anaerobic reactor (n = 15), six antibiotics and caffeine were detected in concentrations ranging from 0.018 to 1097 μg L(-1). To guarantee a reliable quantification, standard addition was used to overcome the matrix effect.

Global Assessment of Bisphenol A in the Environment: Review and Analysis of Its Occurrence and Bioaccumulation

Because bisphenol A (BPA) is a high production volume chemical, we examined over 500 peer-reviewed studies to understand its global distribution in effluent discharges, surface waters, sewage sludge, biosolids, sediments, soils, air, wildlife, and humans. Bisphenol A was largely reported from urban ecosystems in Asia, Europe, and North America; unfortunately, information was lacking from large geographic areas, megacities, and developing countries. When sufficient data were available, probabilistic hazard assessments were performed to understand global environmental quality concerns. Exceedances of Canadian Predicted No Effect Concentrations for aquatic life were >50% for effluents in Asia, Europe, and North America but as high as 80% for surface water reports from Asia. Similarly, maximum concentrations of BPA in sediments from Asia were higher than Europe. Concentrations of BPA in wildlife, mostly for fish, ranged from 0.2 to 13 000 ng/g. We observed 60% and 40% exceedences of median levels by the US Centers for Disease Control and Prevention's National Health and Nutrition Examination Survey in Europe and Asia, respectively. These findings highlight the utility of coordinating global sensing of environmental contaminants efforts through integration of environmental monitoring and specimen banking to identify regions for implementation of more robust environmental assessment and management programs.

Emerging pollutants in the Esmeraldas watershed in Ecuador: discharge and attenuation of emerging organic pollutants along the San Pedro-Guayllabamba-Esmeraldas rivers

Water quality characteristics and emerging organic pollutants were sampled along the San Pedro-Guayllabamba-Esmeraldas River and its main water pollution streams in the summer of 2013. The annual flow rate of the stream is 22 000 Mm(3) y(-1) and it collects the wastewater of Quito-Ecuador in the Andes and supplies drinking water to the city of Esmeraldas near the Pacific Ocean. The most persistent emerging pollutants were carbamazepine and acesulfame, which were found to be stable along the San Pedro-Guayllabamba-Esmeraldas River, whereas the concentration of most other organic emerging pollutants, such as caffeine, sulfamethoxazole, venlafaxine, O-desmethylvenlafaxine, and steroidal estrogens, was degraded to a large extent along the 300 km flow. The mass rate of the sum of cocaine and benzoylecgonine, its metabolite, was increased along the stream, which may be attributed to coca plantations and wild coca trees. This raises the possibility of using river monitoring as an indirect way to learn about changes in coca plantations in their watersheds. Several organic emerging pollutants, such as venlafaxine, carbamazepine, sulphamethoxazole, and benzoylecgonine, survived even the filtration treatment at the Esmeraldas drinking water system, though all except for benzoylecgonine are found below 20 ng L(-1), and are therefore not likely to cause adverse health effects. The research provides a way to compare drug consumption in a major Latin American city (Quito) and shows that the consumption of most sampled drugs (carbamazepine, venlafaxine, O-desmethylvenlafaxine, sulphamethoxazole, ethinylestradiol) was below their average consumption level in Europe, Israel, and North America.

Occurrence and removal of estrogens in Brazilian wastewater treatment plants

This paper evaluated the occurrence and removal efficiency of four estrogenic hormones in five biological wastewater treatment plants (WWTPs), located in the State of Ceará, Brazil. The five WWTPs comprised: two systems consisted of one facultative pond followed by two maturation ponds, one facultative pond, one activated sludge (AS) system followed by a chlorination step, and one upflow anaerobic sludge blanket (UASB) reactor followed by a chlorination step. Estrogen occurrence showed a wide variation among the analyzed influent and effluent samples. Estrone (E1) showed the highest occurrence in the influent (76%), whereas both 17β-estradiol (E2) and 17α-ethynylestradiol (EE2) presented a 52% occurrence, and the compound 17β-estradiol 17-acetate (E2-17A), a 32% one. The occurrence in the effluent samples was 48% for E1, 28% for E2, 12% for E2-17A, and 40% for EE2. The highest concentrations of E1 and EE2 hormones in the influent were 3050 and 3180 ng L(-1), respectively, whereas E2 and E2-17A had maximum concentrations of 776 and 2300 ng L(-1), respectively. The lowest efficiencies for the removal of estrogenic hormones were found in WWTP consisted of waste stabilization ponds, ranging from 54 to 79.9%. The high-rate systems (AS and UASB), which have chlorination as post-treatment, presented removal efficiencies of approximately 95%.

Photodegradation of bisphenol A in aqueous medium: monitoring and identification of by-products by liquid chromatography coupled to high-resolution mass spectrometry

RATIONALE

Environmental bisphenol A (BPA) contamination is currently a matter of concern. This compound can disrupt the endocrine system by mimicking natural hormones and cause adverse effects on different organisms. In addition, it has been suggested that BPA can impair brain development, especially in fetuses and children. To efficiently remove BPA from contaminated water and wastewaters, several emerging technologies have been developed. Most are based on photodegradation. However, by-products resulting from the application of such methods have not been properly characterized.

METHODS

The photodegradation of BPA was conducted using two different methods: photocatalysis (TiO2/UV-A and TiO2/UV-C systems) and direct photolysis (UV-A and UV-C radiation). The degradation process was continuously monitored to identify and observe the by-products formed under these conditions. Direct infusion electrospray ionization coupled to high-resolution mass spectrometry in negative ion mode [ESI(-)-HRMS] and liquid chromatography coupled to high-resolution mass spectrometry (HPLC/HRMS) were employed to monitor these by-products.

RESULTS

The results revealed that the TiO2/UV-C system was the most efficient in causing both BPA depletion and mineralization of the organic matter in solution. Moreover, accurate mass data allowed for the assignment of molecular formulae for seven by-products, many of them unprecedented, formed under these conditions. Thus, a route for the photodegradation of BPA in aqueous medium could be proposed based on these results. Finally, additional tests revealed that the by-products showed a higher toxicity against Artemia salina than the primary precursor.

CONCLUSIONS

All of these findings indicate that the identification of by-products arising from oxidative treatments is of primary importance because such compounds can be more hazardous than their precursors.