Sewage Treatment Plant Effluent Research Articles

Do environmental pharmaceuticals affect the composition of bacterial communities in a freshwater stream? A case study of the Knivsta river in the south of Sweden

Pharmaceutical substances present at low concentrations in the environment may cause effects on biological systems such as microbial consortia living on solid riverbed substrates. These consortia are an important part of the river ecosystem as they form part of the food chain. This case study aims to contribute to an increased understanding of how low levels of pharmaceuticals in freshwater streams may influence sessile bacterial consortia. An important point source for pharmaceutical release into the environment is treated household sewage water. In order to investigate what types of effects may occur, we collected water samples as well as riverbed substrates from a small stream in the south of Sweden, Knivstaån, upstream and downstream from a sewage treatment plant (STP). Data from these samples formed the base of this case study where we investigated both the presence of pharmaceuticals in the water and bacterial composition on riverbed substrates. In the water downstream from the STP, 19 different pharmaceuticals were detected at levels below 800 ng/dm3. The microbial composition was obtained from sequencing 16S rRNA genes directly from substrates as well as from cultivated isolates. The cultivated strains showed reduced species variability compared with the data obtained directly from the substrates. No systematic differences were observed following the sampling season. However, differences could be seen between samples upstream and downstream from the STP effluent. We further observed large similarities in bacterial composition on natural stones compared to sterile stones introduced into the river approximately two months prior to sampling, giving indications for future sampling methodology of biofilms.

Effects of natural sunlight on antimicrobial-resistant bacteria (AMRB) and antimicrobial-susceptible bacteria (AMSB) in wastewater and river water

The effects of natural sunlight on antimicrobial-resistant bacteria (AMRB) and antimicrobial-susceptible bacteria (AMSB) were investigated in three types of water: sewage treatment plant (STP) influent, STP secondary effluent, and river water in an urban area of Japan. The AMRB were grouped into six classes: carbapenem-resistant Enterobacteriaceae (CRE), extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E), multi-drug-resistant Acinetobacter (MDRA), multi-drug-resistant Pseudomonas aeruginosa (MDRP), methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus (VRE). The amount of each group of bacteria present was estimated using specific chromogenic agar formulations. AMRB were detected in all water samples, with 13–2,407 colony-forming units (CFU)/mL in the STP influent, N.D. to 202 CFU/mL in the secondary STP effluent, and N.D. to 207 CFU/mL in the river water. The distribution profiles of the AMSB in water samples were similar to those of AMRB. The degree to which AMRB and AMSB present in the river water were inactivated by natural sunlight was tested as the main aim of this study. Irradiation by natural sunlight was found to inactivate almost 100% of all the target AMRB after 5 h of exposure, with no significant differences (P < 0.05) observed in the effects that sunlight had on AMSB and AMRB. Analysis of the bacterial community structure based on 16S rRNA gene sequencing showed that the structure of the bacterial community was apparently not affected by the exposure to sunlight. In addition, the taxonomic diversity in the STP secondary effluent did not change as a result of additional disinfection with chlorine. The results of this study suggest that it is possible that exposure to sunlight could be used as an alternative to disinfection via chlorine. To our knowledge, this is the first report to demonstrate the mitigation of AMSB and AMRB pollution in a river environment via the exposure to natural sunlight.

Associations between pharmaceutical contaminants, parasite load and health status in brown trout exposed to sewage effluent in a small stream

Owing to their widespread use, pharmaceuticals have become important pollutants of the aquatic environment. Pharmaceuticals and parasites can affect the immunity, physiology and behaviour of target organisms, both singly and through interaction. In this study, we related pharmaceutical concentration, parasite infection and condition in brown trout (Salmo trutta m. fario) collected at localities upstream and downstream of a sewage treatment plant (STP). The sites were separated by a weir preventing fish migration. Pharmaceutical number and concentrations differed significantly between sites. Antibiotics and antidepressants were found at the highest concentrations at both localities. Though fish condition and overall parasite abundance did not differ between sites, there was a significant difference in parasite community composition. A higher abundance of monogenean ectoparasites, along with a lower abundance of endoparasites, was observed at the downstream locality. The adverse effect of pharmaceutical load on ecto- and endoparasitic species on brown trout was further confirmed at the individual level using multivariate analysis. Both the number and concentration of pharmaceuticals in fish tissues reflected their high incidence in the environment, confirming the ability of trout to bioaccumulate pharmaceuticals. This could have important consequences on fish health, particularly in small streams where STP effluent represents a high proportion of stream flow.

Shifting the imbalance: Intentional reuse of Dutch sewage effluent in sub-surface irrigation

Worldwide, agricultural irrigation currently accounts for 69% of freshwater withdrawal. Countries with a temperate climate, such as the Netherlands, experience periodic freshwater shortages in agriculture. The pressure on available freshwater will increase due to climate change and a growing demand for freshwater by e.g. industrial activities. Possible alternative water resources are considered in order to meet the current and future water demand. In this study we explore where, and how much, sewage treatment plant (STP) effluent can directly be reused in agricultural sub-surface irrigation (SSI) during an average and a dry season scenario, for all active (335) Dutch STPs. SSI systems may have a higher water demand as part of the STP effluent is transported with groundwater flow, although aboveground irrigation has a loss of water due to interception. Furthermore, such aboveground irrigation systems provide direct contact of crops with irrigation water. SSI systems provide a soil barrier which may function as a filter and buffer zone. In the Dutch situation, direct intentional reuse of STP effluent can fulfill up to 25% of croplands SSI water demand present within a five-kilometer transport buffer from the STPs during an average season and 17% during a dry season. Hereto, respectively, 78% and 84% of the total available Dutch STP effluent would be used. Thus, the intentional direct STP effluent reuse in agricultural SSI has the potential to satisfy a significant amount of the agricultural water demand at a national scale, presuming responsible reuse: safe applications for humans and environment and no limiting effects on water availability for other actors.

Evaluating environmental impact of STP effluents on receiving water in Beijing by the joint use of chemical analysis and biomonitoring

To evaluate the environmental impact of receiving water from the Qinghe River sewage treatment plant (STP) effluents in Beijing, we collected sediments and Bellamya aeruginosa (Up-site, Discharge-site, and Down-site) both in 2017 and 2018 and analyzed the samples via chemical analysis, biological responses and transcriptomics. In two years of data, our biological results showed that AChE activities presented different degrees of influence on B. aeruginosa captured at sampling points of the STP compared to control sites (P < 0.05). Additionally, indicators of the antioxidant system (e.g., SOD, CAT, GST, EROD activity) and MDA content were significantly increased in the whole tissue at the Up-site of the STP. Integration of the assessed biomarkers using the integrated biomarker response (IBR) index ranked the environmental impact at sites as Up-site > Discharge-site > Down-site. In terms of the transcriptome data, B. aeruginosa collected from the Discharge-site of the STP showed greater transcriptomic response than it did from all other sites. KEGG pathway analysis revealed that sewage significantly altered the expression of genes involved in xenobiotics by cytochrome P450, drug metabolism-cytochrome P450, glutathione metabolism, oxidative phosphorylation, citrate (TCA) cycle, glycolysis/gluconeogenesis, apoptotic and Parkinson's disease. The concentrations of 34 organic pollutants (17 PAHs, 10 PAEs, 7 EDCs) were measured. The chemical concentrations of pollutants decreased from Up-site to Down-site and were well correlated with enzyme activity, IBR, and transcriptomic results. Our results demonstrated that the combined use of chemical analysis, biological responses and transcriptome data is necessary to validate the efficacy of a battery of biomarkers chosen to detect environmental stress due to pollution.

Emerging contaminants in aquatic environments and coastal waters affected by urban wastewater discharge in Thailand: An ecological risk perspective

Emerging contaminants such as synthetic musks and UV-filters as ingredients personal care products were widely used in human daily life in Thailand. The occurrence and fate of four synthetic musks and nine UV-filters were investigated in eight full-scale sewage treatment plants (STPs) and their receiving aquatic environments in Bangkok and Pattaya, Thailand. All target compounds were detected in every single sample from STPs and surface water with magnitude from ng/L to μg/L. HHCB-lactone and HMS were found as the predominant musk and UV filter in influent and effluent of STPs, respectively. HHCB-lactone was also found with the highest concentration up to 79501 ng/g (dw) in the sludge. Low removal efficiency range from −37% (HHCB-lactone) to 58% (AHTN) were found for four musks in the STPs. The total emission of Σ4musks and Σ9UV-filters were estimated to be up to 16.7 mg/person/day and 0.28 mg/person/day by the STPs. Three synthetic musks and seven UV-filters were detected in fish from the receiving river. Concentration and emission of musks and UV filters found in this study from Thailand were much higher than those reported in many other countries worldwide. The preliminary ecological risk assessment showed that Musk xylene, 4-MBC and OC may pose high risk to aquatic organisms in the riverine and estuarine environment in Thailand.

Uneven genotypic diversity of Escherichia coli in fecal sources limits the performance of a library-dependent method of microbial source tracking on the southwestern French Atlantic coast.

To develop a library-dependent method of tracking fecal sources of contamination of beaches on the Atlantic coast of southwestern France, a library of 6368 Escherichia coli isolates was constructed from samples of feces, from 40 known human or animal sources collected in the vicinity of Arcachon Bay in 2010, and in French Basque Country, Landes, and Béarn, between 2017 and 2018. Different schemes of source identification were tested: use of the complete or filtered reference library; characterization of the isolates by genotypic or proteomic profiling based on ERIC-PCR or MALDI-TOF mass spectrometry, respectively; isolate by isolate assignment using either classifiers based on the Pearson similarity or SVM (support vector machine). With the exception of one source identification scheme, which was discarded since it used self-assignment, all tested schemes resulted in low rates of correct classification (<35%) and significant rates of incorrect classification (>15%). The heterogeneous coverage of E. coli genotypic diversity between sources and the uneven distribution of E. coli genotypes in the library likely explain the difficulties encountered in identifying the sources of fecal contamination. Shannon diversity index of sources ranged from 0 for several wildlife species sampled once to 3.03 for sewage treatment plant effluents sampled on various occasions, showing discrepancies between sources. The uneven genotypic composition of the library was attested by the value of the Pielou index (0.54), the high proportion of nondiscriminatory genotypes (>91% of the isolates), and the very low proportion of discriminatory genotypes (<3%). Since efforts made to constitute such a library are not affordable for routine analyses, the results question the relevance of developing such a method for identifying sources of fecal contamination on such a coastline.

Concentrations of Typical Perfluoroalkyl Acids and Contributions of Their Precursors in the Water of the Le'an River in China

Transformation of perfluoroalkyl substance (PFASs) precursors and their contribution to PFASs pollution have become a subject of great research interest. The concentration of PFASs and their precursors and the transformation of precursors in the water samples collected from Le'an River and the effluents of sewage treatment plants (STPs) were investigated based on methods including hydroxyl radical (·OH) oxidation, extraction by solid phase, and ultra-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The results of the study revealed that the PFAS concentrations were in the range of 14.89-40.84 ng·L-1and 58.63-114.87 ng·L-1, and averaged 28.76 ng·L-1 and 86.75 ng·L-1 in the water of the Le'an River and the STP effluents, respectively. The compound with the highest concentration for the two kinds of waterbodies was perfluorooctanesulfonic acid (PFOS). The PFAS concentrations showed obvious spatial differences in the water of the Le'an River. After the oxidation treatment, the PFAS concentrations clearly increased in the two kinds of waterbodies. The increased concentrations of short-chain perfluorocarboxylic acids with carbon atom numbers of 4-8 (ΣΔ［PFCAC4-C8］oxidation conversion) were higher than those of compounds with long carbon chains. However, the increased concentrations of PFCAs for the STP effluents were higher than those for the river water. The transformation ratio obtained from the increased concentration of PFCAs led by the oxidation treatment against the PFCA concentration before oxidation (ΔPFCAoxidation conversion/PFCAbefore oxidation) was lower for the STP effluents than those for the water of Le'an River, which might be induced by the precursors' degradation during the sewage treatment process.

Super typhoon induced high silica export from Arakawa River, Japan.

Dissolved silicate (DSi) and particulate silica (PSi) concentrations were measured at Arakawa River and at sewage treatment plants (STP) during October 2018 to October 2019. These included flooding observations after super Typhoon Hagibis. At ordinary water levels, the STP effluents were found to be the largest source of DSi in the river. Although DSi concentrations during the flooding events (165μmolL-1) decreased by about 25% compared to that of ordinary water level (221μmolL-1), PSi was more than sixteen times higher value (301μmolL-1) compared to that of ordinary water level (18μmolL-1). Loading amounts of DSi and PSi (± 1 standard error) were 1.5 × 108 (± 0.1 × 108) and 0.15 × 108 (± 0.02 × 108) mol year-1, respectively, excluding the data of Typhoon Hagibis. Loading amounts during flooding events of DSi and PSi were 1.2 × 108 (± 0.1 × 108) and 2.4 × 108 (± 0.4 × 108) mol 15days-1, respectively. Although the silica loading at ordinary water level was mainly derived from DSi, the silica loading during flooding events was extremely large due to both high level of DSi and PSi; moreover, it was higher than the annual loading amount.

Reducing toxicity and antimicrobial activity of a pesticide mixture via photo-Fenton in different aqueous matrices using iron complexes

This is the first study to investigate ethylenediamine-N,N′-disuccinic acid (EDDS)/photo-Fenton process to polish real wastewater containing pesticides for possible water reuse. To this end, simultaneous degradation of pesticides ametrine, atrazine, imidacloprid and tebuthiuron was evaluated in distilled water (DW) and in sewage treatment plant (STP) effluent at initial pH 6.0. Several operational parameters (Fe3+-EDDS concentration, Fe3+-EDDS molar ratio, EDDS addition patterns and radiation source) were evaluated. 80–98% removal of target pesticides were obtained in DW using 30 μmol L−1 of Fe3+-EDDS with a molar ratio of 1:2 (300 μmol L−1 of H2O2). In addition, the proposed Fe3+-EDDS photo-Fenton at pH 6 was more efficient than classic photo-Fenton at pH 2.7 (30–84% removal). Experiments conducted in the presence of radical trapping agents (2-propanol or chloroform) revealed that HO• was the most active radical during treatment. Matrix composition strongly affected the degradation of target pesticides as a six-fold higher concentration of reagents (180 μmol L−1 of Fe3+-EDDS and 1800 μmol L−1 of H2O2) was needed to reach the same efficiency in STP compared to DW. Even so, first order rate constants corresponding to the degradation of pesticides in DW (k = 0.098–0.85 min−1) were nearly two-fold higher than in STP (k = 0.079–0.49 min−1) under the same radiation source (black-light or solar radiation). Finally, acute toxicity towards Vibrio fischeri and Drosophila melanogaster flies, and antibacterial activity assessed for Escherichia coli were eliminated after the application of the proposed treatment, thus indicating environmental safety for either discharge or reuse of treated wastewater for crop irrigation in agriculture.

Degradation mechanism of fipronil and its transformation products, matrix effects and toxicity during the solar/photo-Fenton process using ferric citrate complex

This study presents the degradation of fipronil in sewage treatment plant (STP) effluent by photo-Fenton at near neutral pH (pH 6.0) using Fe3+/Citrate complex. 83% of fipronil degradation was reached using a molar iron/citrate ratio of 1:3 (192 μmol L−1 of Fe3+/576 μmol L−1 of citrate). Photo-Fenton reduced the toxicity of treated solutions as according to the survival of Drosophila melanogaster exposed to non-treated and treated samples. Control experiments performed in distilled water using 32 μmol L−1 of Fe3+/96 μmol L−1 of citrate achieved 98% of fipronil degradation within 100 kJ m−2 (UV-A radiation, k = 30 × 10−3 kJ−1 m2 and t1/2 = 23 kJ m−2), thus indicating that fipronil degradation is impaired by natural organic matter and inorganic ions present in STP effluent. Degradation was faster under solar radiation, as the same efficiency (98%) was obtained after 75 kJ m−2 (k = 63 × 10−3 kJ−1 m2 and t1/2 = 11 kJ m−2). In addition, pathways of fipronil degradation using Fe3+/Citrate under solar and UV-A radiation were investigated and transformation products proposed. Results revealed that the HO• attack occurred preferentially in the pyrazole ring. Eight transformation products were identified by UHPLC-Q-TOF-MS and four are unprecedented in the literature. Control experiments in distilled water demonstrated that toxicity reduction is related to fipronil degradation and that transformation products are less toxic than fipronil. Furthermore, toxicity of STP fortified with fipronil was reduced after photo-Fenton. These results demonstrate the feasibility of applying this process using Fe3+/Citrate complex for fipronil degradation in a real matrix.

Spatiotemporal distributions and ecological risk assessment of pharmaceuticals and personal care products in groundwater in North China

Abstract The contamination of surface water by pharmaceuticals and personal care products (PPCPs) has attracted widespread attention, but data regarding their impacts on groundwater (GW) are sparse. In river–GW interaction areas, rivers are likely an important source of PPCPs in aquifers, especially rivers impacted by sewage treatment plant effluent. Understanding the characterization, transport, and risk is valuable for the effective protection of vital aquatic ecosystem services, environmental health, and drinking water supplies. To attain this objective, statistics with spatial analysis and ecological risk were used to assess the effects of artificial recharge (AR) engineering on 16 PPCPs in aquifers in North China. The results indicated that 15 PPCPs were detected in unconfined and confined aquifers, with a few PPCPs being detected up to 1,000 ng/L. The most frequently detected PPCPs were sulfisoxazole, sulfachloropyridazine, sulfamerazine, sulfamethazine, sulfamethoxazole, and ibuprofen. In addition, the spatial and seasonal variations in most PPCPs were significant. Furthermore, the maximum concentrations were compared to the predicted no-effect concentrations to evaluate the ecological risk, and four PPCPs were found to be of medium or high ecological risk. This study highlights that AR engineering has a significant ecological effect on GW.

Facilitated decrease of anions and cations in influent and effluent of sewage treatment plant by vetiver grass (Chrysopogon zizanioides): the uptake of nitrate, nitrite, ammonium, and phosphate.

The ability of vetiver grass (Chrysopogon zizanioides L.) for the reduction of anions and cations especially inorganic nitrogen compounds from the influent and effluent of sewages was investigated. Vetiver grass was grown hydroponically in influent (IN) and four different effluent (EF) sewages including control, 125 (EF125), 250 (EF250), and 500 (EF500) mgL-1 Ca(NO3)2. During 18days, phosphate concentration gradually declined in both influent and all effluent treatments. Unlike effluent treatments, the amount of ammonium in influent was greater than the standard (39.52mgL-1) and decreased severely down to 4.85mgL-1 at the end of the experiment. After just 48h, the concentration of nitrate in EF treatment reached 2.25mgL-1 that is lower than the standard. The decrease of nitrate to concentrations less than the standard was also observed at days 8, 11, and 18 in EF125, EF250, and EF500 treatments, respectively, and about 90% of nitrate had been removed from 500mgL-1 Ca(NO3)2 treatment. Other ions such as Cl-, Ca2+, and K+ decreased in influent and all effluent sewages due to phytoremediation process. Accordingly, phytoremediation by vetiver grass could decrease concentrations of nitrate, ammonium, phosphate, chloride, and calcium in influent and all effluent sewages. Increasing the concentration of nitrate resulted in the increase in its uptake rate. In addition, a positive correlation was shown between the uptake rate of nitrate by vetiver grass and the duration of cultivation of this plant in nitrate-containing medium.

Metabolic regimes of three mid-order streams in southern Ontario, Canada exposed to contrasting sources of nutrients

Light, temperature, and discharge control stream metabolism, but the response of gross primary production (GPP) and ecosystem respiration (ER) to seasonal variation in these physical drivers may differ in accordance with the types of human activities present in the catchment. Our study examined three mid-order streams in southern Ontario, Canada that differed in anthropogenic nutrient sources (i.e., sewage treatment plant effluent, sewage lagoon effluent, and agriculture), but had comparable light, temperature, and discharge regimes. For each stream, GPP and ER were estimated daily from June through November. Comparisons of paired daily metabolic rates revealed pairwise differences among all streams, with streams receiving sewage effluent having greater rates and variability of GPP and ER than the stream draining agricultural land. The two sewage influenced streams differed only in ER. Temporal patterns of GPP and ER were correlated for all streams throughout the study period and were most affected by seasonal variation in temperature, whereby effluent receiving streams responded more rapidly to increases in temperature. Our findings suggest that managers may need to balance effects of human activities with regional environmental constraints on stream metabolism to maintain and enhance the ecological condition and services of stream ecosystems.

Pollution Characteristics and Risk Assessment of Typical Organophosphate Esters in Beijing Municipal Wastewater Treatment Plant and the Receiving Water

Organophosphate esters (OPEs) are ubiquitous in the environment and pose a potential threat to ecosystems and human health. A method for the determination of eight OPEs by ultra-performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS) was established. The recovery rates of eight target compounds with different solid-phase extraction columns, different eluents, and different eluent volumes were compared. The results showed that using ENVI-18 column enrichment, OPEs were eluted with 8 mL acetonitrile containing 25% (volume fraction) dichloromethane, and the labeled recovery rate of the target compound was 92.5%-102.2%. The recoveries of different matrix samples were 88.5%-116.1% and relative standard deviation was 1.7%-9.9%. The concentration range of 8 different detectable organophosphate esters in the effluent of sewage treatment plant is 85.9-235.4 ng·L-1 during the six-day sampling process, permissive river downstream of the six-day ΣOPEs average total concentration was 130.3 ng·L-1, higher than the 119.4 ng·L-1 upstream water concentration, but lower than the sewage treatment plant effluent concentration of total 162.5ng·L-1. The study shows that the sewage treatment plant cannot completely remove OPEs; for triethyl phosphate (TEP) and 3 (2-ethyl hexyl) phosphate ester (TEHP) there exists a negative removal phenomenon, whereas for other OPEs the removal rate was between 14.1% and 84.9%, and the total ΣOPEs removal rate by the sewage plant was 50.0%. The TPhP in the effluent of the sewage treatment plant has medium environmental risk (RQ>0.1), and other organophosphates have low environmental risk (RQ<0.1); however, the long-term mixing effects of organophosphate esters on the ecosystem of the receiving river should not be ignored.

Spatial distribution of perfluoroalkyl acids (PFAAs) and their precursors and conversion of precursors in seawater deeply affected by a city in China.

Conversion of perfluoroalkyl acid (PFAA) precursors in the environment has been a hotspot research in recent years. This study firstly determined the spatial distribution of PFAAs and their precursors including 8:2 fluorotelomer unsaturated acid (8:2 FTUCA), perfluorooctane sulfoneamide (FOSA), and diperfluorooctane sulfonamido ethanol-based phosphate (di-SAmPAP), then investigated the conversion of the potential precursors in the seawater and sewage treatment plants (STPs) effluents. The results indicated that the target pollutants showed a typical concentration gradient from nearshore to offshore. And the obviously increased concentration of perfluorinated carboxylic acids (△[PFCAs]) after oxidation treatment can verify the existence of PFAA precursors in the seawater and STP effluents. The concentrations of PFCAs with carbon atom numbers 4-9 (PFCAC4-C9) revealed the most increase. Moreover, the levels of △[PFCAs] and the ratios of △[PFCAs] to their concentration before oxidation (△[PFCA]/[PFCA]before oxidation) indicated obvious spatial variations in the seawater and STP effluents. The higher levels of △[PFCAC4-C12] and the lower ratios of ∑△[PFCAC4-C12]/∑[PFAA]before oxidation were observed in the STP effluents, which implied that precursors might be decomposed during the sewage treatment process. These results suggested the STP effluents might have an important effect on the PFAAs levels of seawater.

Impact of sewage treatment plant effluent on water quality of Dal Lake, Kashmir, India

Present paper attempts to study and discuss the impacts of sewage treatment plant effluent on water quality of a typical urban Dal Lake situated in Jammu & Kashmir. Using Correlation analysis and Principal component analysis changes in water quality were analysed. The result showed that Fluidised Aerobic Bed reactor (FAB) based STP was malfunctioning and resulted in increasing the concentration of electrical conductivity, othro-phosphate, nitrate-nitrogen and nitrate-nitrogen at influx of sewage into the lake. This has resulted in bifurcating the lake into two distinct zones, one being polluted and other being unpolluted. The main reason being the release of partially treated effluents directly into the lake.

Phosphorus Forms and Release Risk of Sediments in Urban Sewage Treatment Plant Effluent and Receiving Stream Reach

From October 2018 to April 2019, the surface sediment and overlying water samples were collected every two months from the upstream and downstream of the effluent outlet of the Caitianpu sewage treatment plant in the Banqiao River, Hefei City. The effects of the sewage treatment plant effluent on both phosphorus forms and the equilibrium phosphate concentration (EPC0) in sediments were analyzed. The response of equilibrium phosphate concentration to external carbon (sodium acetate) and the release risk of phosphorus in sediments were investigated. Result show that the phosphorus pollution in Banqiao River was more severe. The average values of total phosphorus in the sediments at the upper and lower effluent outlet were 789.39 mg·kg-1 and 854.41 mg·kg-1, respectively, and the average bio-available phosphorus amounts were 157.19 mg·kg-1 and 173.37 mg·kg-1, respectively. The EPC0 values of the four sampling points decreased in the order SP1 > SP2 > SP3 > CP, indicating that the sewage treatment plant effluent increased the EPC0 level and phosphorus release risk of the stream sediments. Moreover, the addition of exogenous carbon significantly decreased the EPC0 value of the sediment, especially in SP1, suggesting that the addition of exogenous carbon decreased the risk of phosphorus release from sediments.

Removal of micropollutants in domestic wastewater by expanded granular sludge bed membrane bioreactor

Sewage treatment plants effluent is considered the primary source of many micropollutants in aquatic systems since their biological treatment is commonly unable to remove persistent micropollutants. However, its efficacy can be achieved with the aid of advanced treatment technologies, such as membrane processes. This work evaluated the removal efficiency of 7 pharmaceuticals (Ketoprofen, Prednisone, Fenofibrate, Fluconazole, Betamethasone, Loratadine and 17α-Ethinyl estradiol) in a hybrid system (EGSB-MBR) where an ultrafiltration membrane was submerged in an anaerobic expanded granular sludge bed (EGSB) reactor. This integrated system improved the removal efficiencies of pharmaceuticals (>84 %) and chemical oxygen demand (COD). The EGSB reactor alone showed COD reductions around 92 %, while the EGSB-MBR system achieved COD reductions above 98 %. Furthermore, the permeate showed lower concentrations of nutrients (P, N-NH4+) and volatile fatty acids (VFAs) than the effluent from the anaerobic reactor alone. Anaerobic biodegradability tests, together with bioreactor results, pointed out the mechanisms involved in the removal of each drug. The risk assessment showed that the permeate presented a low probability of risk to human health and that the UF membrane was able to reduce the risk of the final effluent.

Carbamazepine Ozonation Byproducts: Toxicity in Zebrafish (Danio rerio) Embryos and Chemical Stability.

Carbamazepine (CBZ) is an anticonvulsant medication with highly persistent properties in the aquatic environment, where it has the potential to affect nontarget biota. Because CBZ and many other pharmaceuticals are not readily removed in conventional sewage treatment plants (STP), additional STP effluent treatment technologies are being evaluated and implemented. Whole effluent ozonation is a prospective method to remove pharmaceuticals such as CBZ, yet knowledge on the toxicity of CBZ ozonation byproducts (OBPs) is lacking. This study presents, for the first time, in vivo individual and mixture toxicity of four putative OBPs, that is, carbamazepine 10,11-epoxide, 10,11-Dihydrocarbamazepine, 1-(2-benzaldehyde)-4-hydro-(1H,3H)-quinazoline-2-one (BQM), and 1-(2-benzaldehyde)-(1H,3H)-quinazoline-2,4-dione (BQD) in developing zebrafish (Danio rerio) embryos. BQM and BQD were isolated from the ozonated solution as they were not commercially available. The study confirmed that the OBP mixture caused embryotoxic responses comparable to that of ozonated CBZ. Individual compound embryotoxicity assessment further revealed that BQM and BQD were the drivers of embryotoxicity. OBP chemical stability in ozonated CBZ water solution during 2 week dark storage at 22 °C was also assessed. The OBP concentrations remained over time, except for BQD which decreased by 94%. Meanwhile, ozonated CBZ persistently induced embryotoxicity over 2 week storage, potentially illustrating environmental concern.