This paper presents the abundance, concentration and variability of microplastics (MP) in an urban wastewater treatment plant (WWTP), according to different water parameters and environmental ...factors, their possible sources and removal efficiency. A total of 352.6 L of wastewater from four stages of the treatment process were processed following a standardized extraction protocol by density separation, trinocular microscopic identification and polymeric analysis by Fourier transform infrared spectroscopy. MP comprised a 46.6% of total microlitter, with a statistically significant removal of 90.3% in the final effluent of the WWTP. Five different shapes were isolated; i.e. fragment, film, bead, fiber, and foam. The most prominent MP forms in the final effluent were fragments and fibers, with the most common size class being 400–600 μm. Seventeen different polymer families were identified, with low-density polyethylene being the most prevalent one (52.4%) in a film form (27.7%), mostly from agriculture greenhouses near the sewage plant and single plastic bags (it is noted that only a year ago consumers are charged for them in Spain). Influent wastewater with high concentrations of suspended solids proved to have a low MP burden with a larger MP size, possibly due to a hetero-aggregation with particulate matter. Agglomeration of polystyrene and polyethylene terephthalate with organic material is also suggested, both with surface energies higher than 25 mN m−1 enough for a high biofouling rate. The sewage plant cushions sharp-point microplastic concentrations during the warm season, allowing a stable performance of the WWTP.
Display omitted
•A significant removal of microlitter and microplastics through the WWTP.•Biodegradable polymers proved to disappear in the final effluent.•High suspended solids were correlated to low MP burden and an increasing size.•No seasonal variability in the effluent, despite an increase during the warm season.
•Sewage epidemiology was utilized to determine community use rate of drugs.•Per-capita consumption of methamphetamine and amphetamine was the highest ever reported in the USA.•Codeine and hydrocodone ...were the most consumed prescription opioids.•Venlafaxine and citalopram were discharged at the highest rate from the WWTP to the adjacent creek.•Wastewater effluent found to be a source of drugs in the receiving creek and river
Display omitted
In this study, residues of the neuropsychiatric and illicit drugs including stimulants, opioids, hallucinogens, antischizophrenics, sedatives, and antidepressants were determined in influent and effluent samples from a small wastewater treatment plant, a receiving creek, and river waters in the Four Rivers region of the Midwestern United States. Nineteen neuropsychiatric drugs, eight illicit drugs, and three metabolites of illicit drugs were detected and quantitated in the water samples using HPLC–MS/MS. Residual concentrations of the drugs varied from below the detection limit to sub-μg/L levels. The source of residual cocaine and benzoylecgonine in wastewater is primarily from human consumption of cocaine rather than direct disposal. Wastewater based epidemiology is utilized to estimate the community usage of drugs based on the concentration of drug residues in wastewater, wastewater inflow, and the population served by the centralized wastewater treatment plant. The per-capita consumption rate of methamphetamine (1740 mg/d/1000 people) and amphetamine (970 mg/d/1000 people) found in this study were the highest reported per-capita consumption rates in the USA. Antidepressant venlafaxine found to have the highest environmental emission from the WWTP (333 ± 160 mg/d/1000 people) followed by citalopram (132 ± 60.2 mg/d/1000 people), methamphetamine (111 ± 43.6 mg/d/1000 people), and hydrocodone (108 ± 90.1 mg/d/1000 people). Bee Creek, an immediate receiving water body, is found to be a source of several neuropsychiatric and illicit drugs including methamphetamine, methadone, alprazolam, oxazepam, temazepam, carbamazepine, venlafaxine, citalopram, sertraline, oxycodone, and hydrocodone (p < 0.036) in the Clarks River.
Additional treatment of wastewater, such as constructed wetlands (CWs), is a possible solution to reduce the discharge of antibiotics and antibiotic resistance genes (ARGs) from households and ...industry to the environment. This study aims to investigate the occurrence and removal of antibiotics and ARGs by two full scale CWs operated at different hydraulic retention times (HRT), namely 1 day and 3 days. Both CWs were receiving the same wastewater treatment plant (WWTP) effluent. Temporally and spatially distributed sampling of water and sediment was conducted for one year and samples were analyzed for antibiotics and ARGs by using LC-MS/MS and qPCR. Results showed that both CWs removed antibiotics significantly with a comparable overall removal of 28%–100%, depending on the type of antibiotics. However, some of the antibiotics showed higher concentration after the CW treatment. Five antibiotics (tiamulin, tylosin, oxytetracycline, sulfamethoxazole and trimethoprim) were the most abundant (>1500 ng/l on average) in winter. Meanwhile, ermB was the most abundant (average of 5.0 log) in winter compared to summer (average of 3.5 log). Other ARGs did not show a significant increase or decrease between winter and summer. ARGs were removed from the wastewater by 0.8 to 1.5 log. The HRT did not influence the removal of either the antibiotics or the ARGs. A strong correlation was found between sul genes and intI1. The results also revealed a positive and a negative relationship from sampling point 1 to sampling point 5: a positive relation between abundance of antibiotics, ARGs, and of NO3–N, NH4–N, TP, COD and a negative relation between antibiotics, ARGs and temperature. This relationship showed the effect between antibiotics and ARGs concentrations with physicochemical parameters and nutrients. The ability of CWs to reduce the input of micropollutants into the environment makes CWs a potential post treatment to WWTP.
Display omitted
•TIA, TYL, OTC, SMX and TRI were the most abundant antibiotics in winter.•ARGs except ermB did not show a significant increase or decrease between seasons.•Antibiotic removal for each CW ranges from 13% to 100%.•Log removal of ARGs in the water phase is low (0.8 to 1.5 log).•HRT does not influence the removal of either antibiotics or ARGs.
The presence of most prescribed antibiotic compounds from four therapeutic classes (β-lactam, cephalosporins, macrolides, fluoroquinolones) were studied at two full-scale WWTPs, two rivers, thirteen ...groundwater resources, and five water treatment plants in Tehran. Analytical methodology was based on high performance liquid chromatography/tandem mass spectrometry after solid-phase extraction. Samples were collected at 33 sample locations on three sampling periods over four months from June to August 2016. None of the target antibiotics were detected in groundwater resources and water treatment plants, while seven out of nine target antibiotics were analyzed in two studied river waters as well as the influent and effluent of wastewater treatment plants at concentrations ranging from <LOQ to 926.32ng/L. Ciprofloxacin predominated in all analyzed influent (552.6–796.2ng/L) and effluent (127–248.7ng/L) samples of WWTP A, whereas cephalosporins including cephalexin (523.3–977.7ng/L) and cefixime (278.65 to 422.1ng/L) were the most abundant detected antibiotics in the influent and effluent of WWTP B. Aqueous phase removal efficiencies were assessed and ranged from 339.83% to 100% for the seven detected antibiotics. “Negative removals” were observed for erythromycin, azithromycin, and cefixime due to the deconjugation of conjugated metabolites via biological transformation in the studied WWTPs. From a statistical point of view, significant differences (p<0.05) were observed in the concentrations of cefixime, cephalexin, azithromycin, and erythromycin in the effluent of both studied WWTPs. Ciprofloxacin and cephalexin were the most abundant detected antibiotics in the two studied river waters. Statistical results revealed that there were significant differences in the concentrations of ciprofloxacin, azithromycin, and erythromycin (p<0.05) in Firozabad ditch (receiving WWTP effluent) and Kan River (non-receiving WWTP effluent) which demonstrated that WWTPs discharges could be an important source of antibiotics being released in water bodies.
Display omitted
•Most prescribed antibiotics in Iran were found in two rivers as well as the influent and effluent.•There was a large variation in antibiotic removal from negative removal to 100% in WWTPs.•Negative removal was observed for macrolides.•A significant difference between antibiotics concentration in effluents and rivers were observed.•The target antibiotics were not detected in any of the analyzed ground, source and treated water samples.
•WWTPs are importance MPs generation and formation sources to aquatic environments.•MPs can endure physical abrasion, biodegradation, and chemical oxidation in WWTPs and be fragmented into secondary ...MPs.•Sand crash, biodegradation, and UV/chlorine oxidation are primary mechanisms to MP fragmentation process.•MP weathering in WWTP can further pollute wastewater qualities and interfere wastewater treatment performance.
According to extensive in situ investigations, the microplastics (MPs) determined in current wastewater treatment plants (WWTPs) are mostly aged, with roughened surfaces and varied types of oxygen-containing functional groups (i.e., carbonyl and hydroxyl). However, the formation mechanism of aged MPs in WWTPs is still unclear. This paper systematically reviewed MP fragmentation and generation mechanisms in WWTPs at different treatment stages. The results highlight that MPs are prone to undergo physical abrasion, biofouling, and chemical oxidation-associated weathering in WWTPs at different treatment stages and can be further decomposed into smaller secondary MPs, including in nanoplastics (less than 1000 nm or 100 nm in size), suggesting that WWTPs can act as a formation source for MPs in aquatic environments. Sand associated mechanical crashes in the primary stage, microbes in active sewage sludge-related biodegradation in the secondary stage, and oxidant-relevant chemical oxidation processes (light photons, Cl2, and O3) in the tertiary stage are the dominant causes of MP formation in WWTPs. For MP formation mechanisms in WWTPs, external environmental forces (shear and stress forces, UV radiation, and biodegradation) can first induce plastic chain scission, destroy the plastic molecular arrangement, and create abundant pores and cracks on the MP surface. Then, the physicochemical properties (modulus of elasticity, tensile strength and elongation at break) of MPs shift consequently and finally breakdown into smaller secondary MPs or nanoscale plastics. Overall, this review provides new insights to better understand the formation mechanism, occurrence, fate, and adverse effects of aged microplastics/nanoplastics in current WWTPs.
:
Display omitted
This study proposes a multi-objective optimization model for a grid-connected wind–solar–hydro system in wastewater treatment plants, addressing trade-offs among electricity utilization cost, ...self-sufficiency, complementary effect, and carbon emission. Two modes are explored: one allowing energy export and another leading to curtailment. A case study from a plant with design scale of 50,000 m3/day in China found that a higher complementary rate can slightly increase costs, lower self-sufficiency, and increase carbon emissions. Compared to the initial scheme without the solar–wind–hydro system, the design modes of export and curtail reduce electricity costs by 2.15 and 0.87 million CNY, carbon emissions by 2760 and 1439 tons annually, and increase self-sufficiency to 52% and 42%, respectively. The levelized cost of energy is 25% higher and total installed capacity decreases by 54% when surplus cannot be exported. A 6.7% curtailment minimizes the electricity utilization cost. Complementarity rates show seasonal fluctuations, peaking in August, with the highest yearly rate of 0.1528 at a solar-to-wind capacity ratio of 1.747. Output ratios remain stable across different treatment scales under curtailment mode: imports about 60%, wind and solar about 20% each, and hydropower 2%. Price changes and potential for zero-carbon operation are further discussed.
Display omitted
•Multi-objective planning for wind–solar–hydro in wastewater treatment plant is given.•Self-sufficiency rates are 52% and 42% under export and curtailment modes.•LCOE is 25% higher and installed capacity reduces by 54% when export is not permitted.•Complementarity maximized at solar-to-wind capacity ratio of 1.75 and peaks in August.•Imports ∼60%, wind & solar each ∼20%, hydro ∼2%, stable across treatment scales.
Contaminated water bodies such as rivers provide reservoirs for bacterial resistance. This field study tested the water quality and the bacterial resistance to heavy metals of Qishan River water ...pollution. Wastewater discharged to environmental surface waters is a major pathway of heavy metals and heavy metal-resistant bacteria. Contaminated water bodies such as rivers provide reservoirs for bacterial resistance. This field study tested the water quality and bacterial resistance to heavy metals of Qishan River water pollution. Guided by our research hypothesis that an overall increase in downstream heavy metal resistance levels was following an increase in human settlements were eight sites sampled along the Qishan River. These were situated upstream and downstream to the confluence of the Qishan River with the Kaoping River. In the laboratory bacterial heavy metal resistance was bio-assayed by disk diffusion and micro-dilution with six widely used heavy metals. The comparison of bacterial resistance was among Qishan River upstream sites (sites 1–6) and downstream sites (sites 7–9). Multi-drug-resistant bacteria and co-resistance against heavy metals and antibacterials appeared at site 8. This research discusses the correlation between environmental factors, and antibacterial and heavy metal resistance. The results provide stakeholders and authorities responsible for environmental pollution with a reference for risk assessment and management of bacterial resistance.
Display omitted
•Risks to environmental health result from antibacterial and heavy metal resistance.•Downstream heavy metal resistance indicates different resistance patterns.•Ecotoxicological assessment provides a reference for the relevant authorities.
The occurrence and removal rate of 52 typical pharmaceuticals and personal care products (PPCPs) were investigated in a wastewater treatment plant in Beijing, China. Thirty-three PPCPs were found in ...the influent, with caffeine (CF, 11387.0 ng L−1) being the most abundant, followed by N,N-diethyl-meta-toluamide (DEET, 9568.4 ng L−1), metoprolol (MTP, 930.2 ng L−1), and diclofenac (DF, 710.3 ng L−1). After treatment processes, the cumulative concentration of PPCPs decreased from 2.54 × 104 ng L−1 to 1.44 × 103 ng L−1, with the overall removal efficiency (RE) of 94.3%. Different treatment processes showed varying contributions in removing PPCPs. PPCPs were efficiently removed in sedimentation, anoxic, and ultraviolet units. For individual compounds, a great variation in RE (52.1–100%) was observed. Twenty-two PPCPs were removed by more than 90%. The highly detected PPCPs in the influent were almost completely removed. Aerated grit chamber removed nearly 50% of fluoroquinolone (FQs) and more than 60% of sulfonamides. Most PPCPs showed low or negative removals during anaerobic treatment, except for CF which was eliminated by 64.9%. Anoxic treatment demonstrated positive removals for most PPCPs, with the exceptions of DF, MTP, bisoprolol, carbamazepine (CBZ), and sibutramine. DEET and bezafibrate were efficiently removed during the secondary sedimentation. Denitrification biological filter and membrane filtration also showed positive effect on most PPCPs removals. The remaining compounds were oxidized by 16–100% in ozonation. DF, sulpiride, ofloxacin (OFL), trimethoprim, and phenolphthalein were not amenable to ultraviolet. After the treatment, the residue OFL, CBZ, and CF in receiving water were identified to pose high risk to aquatic organisms. Considering the complex mixtures emitted into the environment, therapeutic groups psychotropics, stimulant, and FQs were classified as high risk. These findings provide valuable insights into adopting appropriate measures for more efficient PPCPs removals, and emphasize the importance of continued monitoring specific PPCPs and mixtures thereof to safeguard the ecosystem.
Display omitted
•33 and 23 PPCPs were detected in WWTP influent and effluent, respectively.•The most abundant PPCPs were CF, DEET, MTP, and DF in influent.•A great variation of PPCPs in removal rates was observed from 52.1% to 100%.•Different treatment processes showed variable contribution in removing PPCPs.•The residue OFL, CBZ, and DF in receiving water pose high risks to aquatic life.
While wastewater treatment plant (WWTP) effluents have become increasingly recognized as a stressor for receiving rivers, their effects on river microbial communities remain elusive. Moreover, global ...change is increasing the frequency and duration of desiccation events in river networks, and we ignore how desiccation might influence the response of microbial communities to WWTP effluents. In this study, we evaluated the interaction between desiccation events and WWTP effluents under different dilution capacities. Specifically, we used artificial streams in a replicated regressional design, exposing first a section of the streams to a 7-day desiccation period and then the full stream to different levels of a realistic WWTP effluent dilution, from 0% to 100% of WWTP effluent proportion of the total stream flow. The microbial community response was assessed by means of high-throughput sequencing of 16S rRNA gene amplicons and quantitative PCR targeting ecologically-relevant microbial groups. Threshold Indicator Taxa Analysis (TITAN) was used, together with model fitting, to determine community thresholds and potential indicator taxa. Results show significant interactions between WWTP effluents and desiccation, particularly when sediment type is considered. Indicator taxa included members of Proteobacteria, Actinobacteria and Cyanobacteria, with abrupt changes in community structure at WWTP effluent proportion of the total flow above 50%, which is related to nutrient levels ranging 4.6–5.2 mg N−NO3−L−1, 0.21–0.32 mg P−PO43−L−1 and 7.09–9.00 mg DOC L−1. Our work indicates that situations where WWTP effluents account for >50% of the total river flow might risk of dramatic microbial community structure changes and should be avoided.
Display omitted
•Interactive effects of a WWTP effluent and desiccation were evaluated.•Individual and interactive effects on bacterial community were identified.•Highest change in bacterial community composition at > 50% of wastewater effluent.•Bacterial indicator taxa to wastewater pollution were identified.
Membrane bioreactors (MBRs) have proven to be an extremely effective wastewater treatment process combining ultrafiltration with biological processes to produce high-quality effluent. However, one of ...the major drawbacks to this technology is membrane fouling. Currently, mechanistic models are often used to estimate membrane fouling through transmembrane pressure (TMP), but their performance is not always satisfactory. In this study, data-driven machine learning techniques consisting of random forest (RF), artificial neural network (ANN), and long-short term memory network (LSTM) are used to build models to predict transmembrane pressure (TMP) at various stages of the MBR production cycle. The models are built with 4 years of high-resolution data from a confidential full-scale municipal WWTP. The model performances are examined using statistical measures such as coefficient of determination (R2), root mean squared error, mean absolute percentage error, and mean squared error. The results show that all models provide reliable predictions while the RF models have the best accuracy. Model uncertainty is quantified to determine the impact of hyperparameter tuning and the variance of extreme predictions. The proposed models can be useful tools in providing decision support to WWTP operators employing fouling mitigating strategies, leading to reduced capital and operational costs.
Display omitted
•Data-driven models are used to predict TMP in an SMBR WWTP.•More than 80,000 samples over 4 years are used to train and test the models.•Three algorithms are used to predict TMP accurately.•Hyperparameter and model structure uncertainties are quantified.•Models created are tools that can be used to mitigate membrane fouling in WWTPs.
PDF
