Wastewater Treatment Plant Discharge Research Articles

Occurrence and distribution characteristics of heavy metals in the surface water of Yongding River Basin, China.

Yongding River is a vital socioeconomic zone in China in providing daily usage for humans, animals, and running of industries and agriculture. This study first provides a comparative assessment for the heavy metal pollution in the surface water from 82 estuarine locations along the basin, including the Guanting Reservoir and seven wastewater treatment plants (WWTPs). The occurrence, distribution, potential sources, and water quality relating to the detected heavy metals were addressed. Eleven typical elements (Pb, Cr, As, Cd, Sb, Ba, V, Ti, Zn, Ni, and Be) were investigated, and the results showed that all the measured concentrations were below the WHO guideline limits. Most heavy metals exhibited higher levels in the middle of Yongding River basin due to the discharge of WWTPs. Pb, Ti, Zn, and Cd in the surface water mainly originated from anthropogenic discharge, while Sb and V were mostly contributed to geogenic sources according to the principal component analysis. Three documented methods, water quality index (WQI), heavy metal pollution (HPI), and Nemerow pollution index (Pn) values, were used to evaluate the contamination monitoring of surface water. All the locations were classified as low and moderate risk except Y12, B2, and Y13 for their Pn values were higher than 1.0. The present study highlights the status of heavy metals in Yongding River basin which is helpful in providing fundamental data for assessment of water quality and the effective protection for Yongding River basin in the future.

Anthropogenic Gadolinium Accumulation and Rare Earth Element Anomalies of River Water from the Middle Reach of Yangtze River Basin, China

Anthropogenic rare earth elements (REEs), such as gadolinium (Gd), lanthanum (La), and samarium (Sm), have emerged as microcontaminants in surface waters. In this study, surface water samples were collected from the middle Yangtze River basin from the metropolitan region of central China (Wuhan). We further evaluated the REE characteristics and anthropogenic Gd contribution. The total dissolved REE concentration in the river ranged as 6.76–99.31 ng L–1, the lowest value globally. Furthermore, the Post-Archean Australian Shale-normalized REE patterns, the negative anomaly of Ce, and the positive anomaly of Sm, Eu, and Gd indicated that heavy REE enrichment occurred in the water body. The anthropogenic Gd (Gdanth) concentration in Fuhe River and Hanjiang River was higher than that in the other rivers, with the difference ascribed to wastewater treatment plant (WWTP) discharges. The total daily discharges of Hanxi WWTP (HX-W) and Sanjintan WWTP (SJT-W) effluent were 53.5 and 13.5 g Gdanth, respectively. These values equate to 31.1 and 12.7 g Gdanth d–1 for HX-W and SJT-W per million people. Therefore, the quantitative evaluation of Gdanth in natural water near large cities warrants more attention.

Riparian Land Use and Hydrological Connectivity Influence Nutrient Retention in Tropical Rivers Receiving Wastewater Treatment Plant Discharge

Riparian areas are recognized for their buffering capacity regarding phosphorus and nitrogen from agricultural and urban runoff. However, their role in attenuating nutrient loads of rivers receiving point source nutrient inputs (e.g., from wastewater treatment plants, WWTPs) is still little understood. Here, we investigated whether ammonium (NH4-N), nitrate (NO3-N), and soluble reactive phosphorus (SRP) retention were influenced by the riparian land use in three Brazilian rivers receiving WWTP effluents. We hypothesized that nutrient attenuation would be potentially influenced by the hydrological connectivity between the main channel and riparian areas with native vegetation. We estimated retention from longitudinal patterns of dilution-corrected nutrient concentrations below the WWTPs. We assessed nutrient retention during periods with high (i.e., the wet) and low connectivity (i.e., the dry season). Relationships between non-conservative (nutrients) and conservative (chloride) solutes in both seasons were used to identify potential changes in the river chemistry due to the hydrological connectivity with the riparian areas. We also evaluated the relationship between net uptake velocities (Vf-net) and the accumulated percent native vegetation cover in the 100-m buffer using linear regressions, comparing the response for each nutrient between seasons with Analysis of Covariance. Slopes of regressions between nutrients and chloride significantly differed between seasons for NO3-N and SRP but not for NH4-N. The relationships between Vf-net and accumulated native vegetation in the riparian buffer presented steeper slopes for SRP in the wet than in the dry season. No significant relationships between NO3-N Vf-net and native vegetation cover were observed in either season. In contrast, increases in Vf-net with increasing vegetation cover were observed for NH4-N in the dry season. In periods with expected higher connectivity, NO3-N and SRP concentrations tended to be lower relative to chloride concentrations, with a potential effect of native vegetation in the riparian area on SRP retention. Our results suggest that seasonal connectivity between nutrient-rich river water and riparian areas is likely to induce changes in the predominant nutrient transformation processes, thereby favoring either nutrient retention or export in such rivers.

Impacts of municipal wastewater treatment plant discharge on microbial community structure and function of the receiving river in Northwest Tibetan Plateau

Wastewater treatment plant (WWTP) effluents carrying plenty of nutrients and micropollutants pose serious threats to receiving rivers, however, the response of microbial community structure and function to WWTP effluents discharge is still poorly understood. To address this knowledge gap, paired water and sediment samples from 17 sites of the Huangshui River, and effluents from 6 WWTPs were collected to investigate the effect of WWTP discharge on riverine microbial communities. Our results revealed that WWTP effluents exerted significant effects on planktonic rather than sedimentary microorganisms in the receiving river. Notably, lower diversity and richness of planktonic communities were observed in the effluent-influenced section (WRW) than other river sections (RW) along the urban river. Meanwhile, network analysis potentially revealed lower stability of co-occurrence patterns of microbial communities in WRW. The remarkably higher antibiotics, nitrate-nitrogen, and water temperature in WRW samples caused by WWTPs played essential roles in shaping the structure and function of planktonic microbial communities. This study suggested the enrichment of multiple-drug resistance genes and destruction of energy metabolisms were caused by sewage effluents, and highlighted the importance of effective management strategies for protecting the ecological health of the receiving river.

Passive sampling and in vitro assays to monitor antiandrogens in a river affected by wastewater discharge

Pharmaceuticals and personal care products, antibiotics, estrogens, and antiandrogens are found widely in aquatic environments. Monitoring studies by sampling surface water and effluents of wastewater treatment plants (WWTPs) have been conducted recently to monitor antiandrogens, which, along with estrogens, cause endocrine disruption. However, few studies have investigated antiandrogenic activity (AA) combined with a chemical analyses of emerging antiandrogens. Therefore, we analyzed the presence and persistence of 12 types of antiandrogens, atrazine, and carbamazepine using grab sampling and polar organic chemical integrative sampler (POCIS) along a river affected by WWTP discharges. Water and sediment samples were collected from the WWTP effluent (WW), as well as upstream (US) and downstream (DS) of the WWTP. We detected only tebuconazole, triclosan, propiconazole, and fluconazole during the two sampling campaigns in 2016 and 2017. Grab sampling of the site WW detected tebuconazole (7–77 ng/L), propiconazole (5–47 ng/L), and fluconazole (6–45 ng/L). However, the concentrations in the river water were below the detection limits. Nevertheless, fluconazole and triclosan were detected by POCIS in the site WW (45.7 and 26.8 ng/L, respectively) and all river samples ranges of 0.3–9.3 and 2.4–3.7, respectively. This detection was attributed to the limit of quantification of POCIS being lower than that of grab sampling. Nilutamide and triclosan were detected in the river sediment, suggesting that their concentrations in the water column were at least partly attenuated through sediment sorption. We also observed AA by analyzing POCIS extracts with the yeast androgen screen assay. The highest AA was found in the site WW and it was still observable several kilometers downstream of the point of discharge despite decreasing. Therefore, the WWTP effluent was most likely contributor to the persistent AA in the river.

UiO-66-based metal organic frameworks for the photodegradation of acetaminophen under simulated solar irradiation

This work reports the solvothermal synthesis of UiO-66-based MOFs with three different ligands and its application to the breakdown of aqueous acetaminophen under simulated sunlight. This pharmaceutical is a representative contaminant of emerging concern that enters water bodies mainly through wastewater treatment plant discharges. The synthesis approach of the MOFs was fitted using a zirconium alkoxide as metal cluster precursor and 2-aminoterephthalic and 2,5-dihydroxyterephthalic acids as ligands to prepare UiO-66-NH2 and UiO-66-(OH)2 MOFs, respectively. These new MOFs have enhanced visible light harvesting and narrower band gap than the UiO-66. Among all, UiO-66-NH2 yielded the highest removal of acetaminophen under simulated solar irradiation in batch test. The activity and stability of UiO-66-NH2 were demonstrated for the first time in a continuous flow test, where stable performance was observed upon 30 h on stream. The degradation pathway of acetaminophen was elucidated based on coupling, ring-opening, and oxidation reactions. DFT calculation confirmed that the indirect semiconductor behavior of UiO-66-NH2 upon light excitation occurred through ligand-ligand charge transfer. Overall, promising UiO-66-based MOFs photocatalysts were obtained for effective degradation of acetaminophen with the assistance of solar light.

Investigating the relationship between the river flow and dissolved solids concentration

A systematic approach was used on monthly data from three hydrometric stations located on the Gheshlagh River (west of Iran) to investigate the flow–concentration relationship and for river base flow analysis. According to the results of this study, the water quality of the Gheshlagh River has been affected by changes in river flow as well as human activities. Using the analysis of flow–concentration relationships obtained for Khalife Tarkhan station, the higher concentration of dissolved solids in groundwater (with a base flow rate from 0.1 to 0.7 m3/s) rather than surface runoff was estimated. Also, in this station, with the increase of river flow and improvement of river self-purification capacity, water quality parameters showed a decreasing trend compared to the groundwater. In Hossein Abad's upstream station, due to low average river flow and discharge of saline drainage from agricultural lands, an increasing trend in the dissolved solids both for groundwater and surface runoff was shown. The trend of spatial changes in river water quality also indicates the high impact of human activities such as fish farms and wastewater discharge of Sanandaj wastewater treatment plant, on increasing the concentration of dissolved solids in Dareh Kolleh downstream station.

Multi-residue analysis of pharmaceuticals in water samples by liquid chromatography- mass spectrometry: Quality assessment and application to the risk assessment of urban-influenced surface waters in a metropolitan area of Central America

The occurrence of pharmaceuticals in surface water has been barely studied in Latin America. This work aimed to i) develop a multi-residue liquid chromatography- triple quadrupole mass spectrometry (LC–MS/MS) method for the determination of pharmaceutical active compounds (PhACs); ii) monitor 70 PhACs in three urban-influenced rivers in San José, Costa Rica; and iii) perform the risk assessment of detected compounds and ecotoxicological evaluation on water samples. Caffeine, 1,7-dimethylxanthine, naproxen, gemfibrozil and ibuprofen were the most frequent among 23 detected compounds. Concentrations ranged from 0.013 μg/L to 53.8 μg/L (62 % detections between 0.1 μg/L–1 μg/L), and the highest values corresponded to caffeine, 1,7-dimethylxanthine, ofloxacin, gemfibrozil and cephalexin. The environmental risk estimated using the hazard quotient (HQ) approach, revealed four and eleven compounds with medium and high risk, respectively. The highest risk (HQ >10) was determined for diphenhydramine, risperidone, fluoxetine, trimethoprim, ofloxacin and azithromycin; nonetheless, high risk (HQ >1) was also estimated for caffeine, diclofenac, clarithromycin, gemfibrozil and ibuprofen. Total HQ sample values (ΣHQ), calculated as the sum of individual HQs for each detected compound, revealed the highest hazard in surface water near wastewater treatment plant discharges, followed by the locations of higher urban influence (in the Virilla river). Ecotoxicological evaluation showed no acute toxicity towards Daphnia magna and Vibrio fischeri in surface water samples; on the contrary, toxicity towards Lactuca sativa (germination tests) showed a similar pattern to that determined with the ΣHQ, although the highest toxicity was observed downstream with respect to the urban influence of the metropolitan area. These findings help to visualize the importance of pharmaceutical residues in the overall toxicity of surface water samples, and remark the relevance of monitoring these compounds, as an input for the implementation of future mitigation actions.

Enhanced natural radioactivity in leachate and groundwater of Belgian landfills

To investigate the potential impact on ground- or surface water of natural radionuclides present in waste disposed onto landfills, activity concentrations in leachates, waste water treatment plant discharge and groundwater of several landfills in Belgium have been analysed. 16 currently in operation landfills for hazardous and non-hazardous waste and 10 legacy landfills have been investigated. Results indicate the presence of a slightly enhanced concentration of uranium and other radionuclides in some leachates of landfills in operation. For legacy landfills, enhanced uranium concentration is also observed in some groundwater wells. The presence of uranium in groundwater around landfills is always accompanied by a contamination with other heavy metals and chlorides. No clear linear correlation between concentration of uranium and other metals could be found however. Isotopic ratio between U-238 and U-234 has been calculated in the different water matrices and is close to one in contaminated groundwater, probably indicating an anthropogenic contamination. In all cases, the concentrations of natural radionuclides do not reach values of concern from radiation protection point of view.

Broad diversity of bacteria degrading 17\xdf-estradiol-3-sulfate isolated from river sediment and biofilm at a wastewater treatment plant discharge

Conjugated estrogens, such as 17β-estradiol-3-sulfate (E2-3S), can be released into aquatic environments through wastewater treatment plants (WWTP). There, they are microbiologically degraded into free estrogens, which can have harmful effects on aquatic wildlife. Here, the degradation of E2-3S in environmental samples taken upstream, downstream and at the effluent of a WWTP was assessed. Sediment and biofilm samples were enriched for E2-3S-degrading microorganisms, yielding a broad diversity of bacterial isolates, including known and novel degraders of estrogens. Since E2-3S-degrading bacteria were also isolated in the sample upstream of the WWTP, the WWTP does not influence the ability of the microbial community to degrade E2-3S.

Increased Antimicrobial and Multidrug Resistance Downstream of Wastewater Treatment Plants in an Urban Watershed.

Development and spread of antimicrobial resistance (AMR) and multidrug resistance (MDR) through propagation of antibiotic resistance genes (ARG) in various environments is a global emerging public health concern. The role of wastewater treatment plants (WWTPs) as hot spots for the dissemination of AMR and MDR has been widely pointed out by the scientific community. In this study, we collected surface water samples from sites upstream and downstream of two WWTP discharge points in an urban watershed in the Bryan-College Station (BCS), Texas area, over a period of nine months. E. coli isolates were tested for resistance to ampicillin, tetracycline, sulfamethoxazole, ciprofloxacin, cephalothin, cefoperazone, gentamycin, and imipenem using the Kirby-Bauer disc diffusion method. Antimicrobial resistant heterotrophic bacteria were cultured on R2A media amended with ampicillin, ciprofloxacin, tetracycline, and sulfamethoxazole for analyzing heterotrophic bacteria capable of growth on antibiotic-containing media. In addition, quantitative real-time polymerase chain reaction (qPCR) method was used to measure eight ARG – tetA, tetW, aacA, ampC, mecA, ermA, blaTEM, and intI1 in the surface water collected at each time point. Significant associations (p < 0.05) were observed between the locations of sampling sites relative to WWTP discharge points and the rate of E. coli isolate resistance to tetracycline, ampicillin, cefoperazone, ciprofloxacin, and sulfamethoxazole together with an increased rate of isolate MDR. The abundance of antibiotic-resistant heterotrophs was significantly greater (p < 0.05) downstream of WWTPs compared to upstream locations for all tested antibiotics. Consistent with the results from the culture-based methods, the concentrations of all ARG were substantially higher in the downstream sites compared to the upstream sites, particularly in the site immediately downstream of the WWTP effluent discharges (except mecA). In addition, the Class I integron (intI1) genes were detected in high amounts at all sites and all sampling points, and were about ∼20 times higher in the downstream sites (2.5 × 107 copies/100 mL surface water) compared to the upstream sites (1.2 × 106 copies/100 mL surface water). Results suggest that the treated WWTP effluent discharges into surface waters can potentially contribute to the occurrence and prevalence of AMR in urban watersheds. In addition to detecting increased ARG in the downstream sites by qPCR, findings from this study also report an increase in viable AMR (HPC) and MDR (E. coli) in these sites. This data will benefit establishment of improved environmental regulations and practices to help manage AMR/MDR and ARG discharges into the environment, and to develop mitigation strategies and effective treatment of wastewater.

Climate change impact on EU rivers' dilution capacity and ecological status

Impacts from urban wastewater treatment plants (WWTP) to receiving riverine surface water bodies (SWBs) depend on the load of contaminants discharged, as well as on their dilution capacity. Yet, climate change impacts on such dilution capacity and ultimately on the SWBs ecological status remain unclear. Here, we assess SWBs dilution capacity across the European continent to identify most vulnerable areas using information from centralized European databases. SWBs´ future dilution factor values are estimated based on representative concentration pathway scenarios impacts on rivers flow, and likely changes in European SWBs´ ecological status foretold. Results show that dilution factor in Europe increases by 5.4% in average. Yet, climate change effects are found to lead to a consistent dilution factor decrease for 11% of the 40074 European SWBs receiving WWTP discharge for the early century. This share reaches 17% for the midcentury period. We estimate that up to 42% of the SWBs receiving WWTP discharges and currently reaching a good ecological status show a 0.7 probability to have their ecological status downgraded due to climate change. Sites more vulnerable are located in the Mediterranean countries. Our findings highlight that climate change mitigation is essential for maintaining good ecological status in European SWBs.

The Effect of the Effluent from a Small-Scale Conventional Wastewater Treatment Plant Treating Municipal Wastewater on the Composition and Abundance of the Microbial Community, Antibiotic Resistome, and Pathogens in the Sediment and Water of a Receiving Stream

The effluents of wastewater treatment plants (WWTPs) are major contributors of nutrients, microbes—including those carrying antibiotic resistance genes (ARGs)—and pathogens to receiving waterbodies. The effect of the effluent of a small-scale activated sludge WWTP treating municipal wastewater on the composition and abundance of the microbial community as well as the antibiotic resistome and pathogens in the sediment and water of the receiving stream and river was studied using metagenome sequencing and a quantitative approach. Elevated Bacteroidetes proportions in the prokaryotic community, heightened sulfonamide and aminoglycoside resistance determinants proportions, and an increase of up to three orders of magnitude of sul1–sul2–aadA–blaOXA2 gene cluster abundances were recorded in stream water and sediments 0.3 km downstream of a WWTP discharge point. Further downstream, a gradual recovery of affected microbial communities along a distance gradient from WWTP was recorded, culminating in the mostly comparable state of river water and sediment parameters 3.7 km downstream of WWTP and stream water and sediments upstream of the WWTP discharge point. Archaea, especially Methanosarcina, Methanothrix, and Methanoregula, formed a substantial proportion of the microbial community of WWTP effluent as well as receiving stream water and sediment, and were linked to the spread of ARGs. Opportunistic environmental-origin pathogens were predominant in WWTP effluent and receiving stream bacterial communities, with Citrobacter freundii proportion being especially elevated in the close vicinity downstream of the WWTP discharge point.

Spatial and temporal distributions of enteric viruses and indicators in a lake receiving municipal wastewater treatment plant discharge.

Although lake water can be used as a source of drinking water and recreational activities, there is a dearth of research on the occurrence and fate of enteric viruses. Over a period of 14months at six points in 2014-2015, we conducted monthly monitoring of the virological water quality of a Japanese lake. The lake receives effluent from three surrounding wastewater treatment plants and retains water for about two weeks. These features allowed us to investigate the occurrence and fate of viruses in the lake environment. Human enteric viruses such as noroviruses and their indicators (pepper mild mottle virus and F-specific RNA bacteriophage [FRNAPH] genogroups) were quantified by PCR-based assays. Additionally, FRNAPH genogroups were quantified by infectivity-based assays to estimate the degree of virus inactivation. Pepper mild mottle virus, genogroup II (GII) norovirus, and GI-FRNAPH were identified in relatively high frequencies (positive in >40% out of 64 samples), with concentrations ranging from 1.3×101 to 2.9×104 copies/L. Human enteric viruses and some indicators were not detected and less prevalent, respectively, after April 2015. Principal component analysis revealed that the virological water quality changed gradually over time, but its differences between the sampling points were not apparent. FRNAPH genogroups were inactivated during the warm season (averaged water temperature of >20°C) compared to the cool season (averaged water temperature of <20°C), which may have been due to the more severe environmental stresses such as sunlight and water temperature. This suggests that the infection risk associated with the use of the lake water may have been overestimated by the gene quantification assay during the warm season.

Effects of climate change and anthropogenic pressures in the water quality of a coastal lagoon (Ria Formosa, Portugal).

Understanding how climatic and anthropogenic drivers will influence coastal lagoons is fundamental to guarantee their preservation and sustainability. The Ria Formosa (coastal lagoon, South coast of Portugal) is a very important ecosystem that supports diverse economic activities in the region. The 3D coupled hydrodynamic-biogeochemical model SCHISM was validated and used to assess the influence of climate change and anthropogenic pressures on the water quality of the Ria Formosa. Five scenarios were simulated: reference scenario (S0), mean sea level rise (SLR) of 0.5m (S1), increase of the air temperature of 1.68°C (S2), increase of the outflow from the wastewater treatment plants (WWTP) by 50% (S3) and a combined scenario (S4). Results suggest that SLR of 0.5m promotes an increase of 0.5-3 in the salinity near the area of influence of the WWTP. SLR decreases the inorganic nutrient concentrations in these areas by about 40-60%, due to an increase of the dilution. In contrast, the increase of the outflow from the WWTP by 50% increases the nutrients concentrations by about 20-40%. The increase of the air temperature alone by 1.68°C increases the water temperature by 0-1°C. The combined scenario suggests antagonist effects in the nutrient concentrations. Overall, the trophic index (TRIX) of the lagoon calculated for the scenarios exhibits only minor differences relative to the reference scenario, except in some areas near the WWTP discharges. In these areas, TRIX tends to increase with the increase of the outflow from the WWTP in scenario S3. These results provide further insight into the response of coastal lagoons, and the Ria Formosa in particular, to future changes and contribute to support their management.

Qualitative and quantitative analysis of microplastics and microfiber contamination in effluents of the City of Saskatoon wastewater treatment plant.

In recent years, contamination of the environment with microplastics has received increasing scientific and public attention. Wastewater treatment plants (WWTPs) are considered important emitters of microparticles into aquatic systems. Among these microparticles are microplastics from, e.g., cosmetic products, and microfibers that are released during laundry of textiles made from synthetic fibers. The purpose of this study was to qualitatively and quantitatively characterize microplastic and microfiber contamination in effluents of the City of Saskatoon WWTP, Saskatchewan, Canada. The WWTP discharges directly into the South Saskatchewan River, which is an important water resource of central economic and environmental importance to the Canadian Prairies. To achieve this goal, a reference dataset was developed by determining Raman and Fourier-transform infrared (FTIR) spectra of neat plastic standards. Subsequently, samples were obtained from the final effluent of the Saskatoon WWTP during winter, spring, and summer 2019 by use of fine-meshed plankton nets. Microplastics and microfibers were extracted using Fenton oxidation and filtration, counted, and their identity determined by comparing Raman and FTIR spectra of individual microplastics and microfibers with the previously developed reference dataset. The number concentrations of both microplastics and microfibers were relatively stable across seasons, and fibers accounted for 82% of the total number of synthetic microparticles. Although the average total number concentration of microplastics and microfibers was only 1.76 per liter of effluent, at an average daily discharge of 80 million liters, this would amount to the emission of 141 million particles into the river per day. While the environmental relevance of these findings remains to be demonstrated, these results are an important first step toward understanding the magnitude of microplastic contamination in the Canadian Prairies.

Presence and Reduction of Anthropogenic Substances with UV Light and Oxidizing Disinfectants in Wastewater—A Case Study at Kuopio, Finland

Anthropogenic substances are a major concern due to their potential harmful effects towards aquatic ecosystems. Because wastewater treatment plants (WWTPs) are not designed to remove these substances from wastewater, a part of the anthropogenic substances enter nature via WWTP discharges. During the spring 2019, the occurrence of anthropogenic substances in the municipal wastewater effluent in Kuopio, Finland, was analysed. Furthermore, the capacity of selected disinfection methods to reduce these substances from wastewater was tested. The disinfection methods were ozonation (760 mL min−1) with an OxTube hermetic dissolution method (1), the combined usage of peracetic acid (PAA) (&lt;5 mg L−1) and ultraviolet (UV) disinfection (12 mJ/cm2) (2), and the combined usage of hydrogen peroxide (H2O2) (&lt;10 mg L−1) and UV disinfection (12 mJ/cm2) (3). The substances found at the concentrations over 1 µg L−1 in effluent (N = 3) were cetirizine (5.2 ± 1.3 µg L−1), benzotriazole (BZT) (2.1 ± 0.98 µg L−1), hydrochlorothiazide (1.7 ± 0.2 µg L−1), furosemide (1.6 ± 0.2 µg L−1), lamotrigine (1.5 ± 0.06 µg L−1), diclofenac (DCF) (1.4 ± 0.2 µg L−1), venlafaxine (1.0 ± 0.13 µg L−1) and losartan (0.9 ± 0.2 µg L−1). The reduction (%) with different methods (1, 2, 3) were: cetirizine (99.9, 5.0, NR = no removal), benzotriazole (67.9, NR, NR), hydrochlorothiazide (91.1, 5.9, NR), furosemide (99.7, 5.9, NR), lamotrigine (46.4, NR, 6.7), diclofenac (99.7, 7.1, 16.7), venlafaxine (91.3, NR, 1.1), losartan (99.6, 13.8, NR). Further research concerning the tested disinfection methods is needed in order to fully elucidate their potential for removing anthropogenic substances from purified wastewater.

Longitudinal Surveillance of Antibiotic Resistance in Escherichia coli and Enterococcus spp. from a Wastewater Treatment Plant and Its Associated Waters in KwaZulu-Natal, South Africa.

We assessed the prevalence, distribution, and antibiotic resistance patterns of Escherichia coli and Enterococcus spp. isolated from raw and treated wastewater of a major wastewater treatment plant (WWTP) in KwaZulu-Natal, South Africa and the receiving river water upstream and downstream from the WWTP discharge point. Escherichia coli and enterococci were isolated and counted using the Colilert®-18 Quanti-Tray® 2000 and Enterolert®-18 Quanti-Tray 2000 systems, respectively. A total of 580 quantitative PCR-confirmed E. coli and 579 enterococci were randomly chosen from positive samples and tested for in vitro antibiotic susceptibility using the disk diffusion assay against 20 and 16 antibiotics, respectively. The removal success of the bacterial species through the treatment procedure at the WWTP was expressed as log removal values (LRVs). Most E. coli were susceptible to meropenem (94.8%) and piperacillin-tazobactam (92.9%), with most Enterococcus susceptible to ampicillin (97.8%) and vancomycin (96.7%). In total, 376 (64.8%) E. coli and 468 (80.8%) Enterococcus isolates showed multidrug resistance (MDR). A total of 42.4% (246/580) E. coli and 65.1% (377/579) enterococci isolates had multiple antibiotic resistance indices >0.2. The LRV for E. coli ranged from 2.97 to 3.99, and for enterococci the range was observed from 1.83 to 3.98. A high proportion of MDR E. coli and enterococci were present at all sampled sites, indicating insufficient removal during wastewater treatment. There is a need to appraise the public health risks associated with bacterial contamination of environmental waters arising from such WWTPs to protect the health of users of the receiving water bodies.

Microfiber Content in Freshwater Mussels from Rural Tributaries of the Saint John River, Canada

Microfibers are now ubiquitous in the environment largely due to the widespread use of natural and synthetic textiles. Many enter aquatic systems through wastewater treatment plant (WWTP) effluent, surface water runoff, and atmospheric deposition, where they persist and may be ingested by filter-feeding organisms. In addition to causing physical damage (e.g., digestive and respiratory obstructions), microfibers are often carriers of chemical pollutants that may also harm biota. This exploratory study aimed to determine whether freshwater mussel (Margaritifera margaritifera L.) microfiber content varied between two rural tributaries of the Saint John River, whether microfiber content was related to WWTP discharge points or potential diffuse microfiber sources, and whether mussel size was associated with microfiber content. Mussels were collected both upstream and downstream of five WWTP discharge points and at 11 other points along two rivers within rural watersheds of maritime Canada. Microfiber content differed significantly between the two rivers; however, no trends were observed in microfiber content in relation to WWTP discharge points on either river. Smaller mussels contained significantly more microfibers than larger mussels, despite differences in mussel size ranges between tributaries. These results reveal a potential pathway for microfibers to enter aquatic food webs and highlight important implications for the use of freshwater mussels as bioindicators of microfiber contamination.

Change in the dynamics of salinity and water quality of an island estuary by the discharge of effluents

ABSTRACT Anthropic changes in coastal watersheds affect the quantity and quality of water in estuaries. Based on an analytical model of saline intrusion and load balance, we have evaluated the effects of effluent discharge (mean of 285 L·s−1 and peak of 495 L·s−1) from a wastewater treatment plant (WWTP) in an island estuary. Saline intrusion at low tide, without actual anthropic discharge, will increase by 22%, whereas with increasing discharge, reductions of 16% and 28%. The reduction of saline intrusion may affect biogeochemical processes and the distribution of species in regions further up the estuary. When the WWTP reaches the mean projected discharge, it will increase its BOD and phosphorus loads by 90% and 82%, respectively, in relation to the current load. With the increase of WWTP discharge, there will be an expansion of hypoxic and anoxic conditions over the current areas, worsening the condition of this already jeopardized estuary. For the WWTP to lead to the expected environmental gains, it is necessary to consider the carrying capacity of the receiving body.