SARS-CoV-2 RNA in wastewater anticipated COVID-19 occurrence in a low prevalence area

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused more than 200,000 reported COVID-19 cases in Spain resulting in more than 20,800 deaths as of April 21, 2020. Faecal shedding of SARS-CoV-2 RNA from COVID-19 patients has extensively been reported. Therefore, we investigated the occurrence of SARS-CoV-2 RNA in six wastewater treatments plants (WWTPs) serving the major municipalities within the Region of Murcia (Spain), the area with the lowest COVID-19 prevalence within Iberian Peninsula. Firstly, an aluminum hydroxide adsorption-precipitation concentration method was validated using a porcine coronavirus (Porcine Epidemic Diarrhea Virus, PEDV) and mengovirus (MgV). The procedure resulted in average recoveries of 10 ± 3.5% and 10 ± 2.1% in influent water (n = 2) and 3.3 ± 1.6% and 6.2 ± 1.0% in effluent water (n = 2) samples for PEDV and MgV, respectively. Then, the method was used to monitor the occurrence of SARS-CoV-2 from March 12 to April 14, 2020 in influent, secondary and tertiary effluent water samples. By using the real-time RT-PCR (RT-qPCR) Diagnostic Panel validated by US CDC that targets three regions of the virus nucleocapsid (N) gene, we estimated quantification of SARS-CoV-2 RNA titers in untreated wastewater samples of 5.4 ± 0.2 log10 genomic copies/L on average. Two secondary water samples resulted positive (2 out of 18) and all tertiary water samples tested as negative (0 out 12). This environmental surveillance data were compared to declared COVID-19 cases at municipality level, revealing that members of the community were shedding SARS-CoV-2 RNA in their stool even before the first cases were reported by local or national authorities in many of the cities where wastewaters have been sampled. The detection of SARS-CoV-2 in wastewater in early stages of the spread of COVID-19 highlights the relevance of this strategy as an early indicator of the infection within a specific population. At this point, this environmental surveillance could be implemented by municipalities right away as a tool, designed to help authorities to coordinate the exit strategy to gradually lift its coronavirus lockdown.

Removal of microplastics in municipal sewage from China's largest water reclamation plant

Municipal sewage treatment plants (STPs) are an important point source of microplastics in domestic waterways. In the present study, effluents from the largest water reclamation plant in China were sampled throughout the treatment process and microplastics were extracted and identified to evaluate their removal. As expected, microplastics were detected in the influent (12.03 ± 1.29 items/L). Following treatment, concentrations of microplastics were reduced by greater than 95% and 0.59 ± 0.22 items/L of microplastics were detected in reclaimed waters. Among detected microplastics, 18 types of polymers of ten colors were identified. Polyethylene terephthalate (PET), polystyrene (PS) and polypropylene (PP) accounted for greater than 70% of detected microplastics. Furthermore, microfibers were the dominant shape detected with an average size of 1110.72 ± 862.95 μm. However, microparticles accounted for only 14.08% of total microplastics with an average size of 681.46 ± 528.73 μm. Results of the present study suggest that current treatment technologies employed at the chosen STP are efficient to remove the majority of microplastics, however consideration of STPs as a point source of microplastics is important due to the large volumes of effluents being released into the aquatic environment on a consistent basis.

Occurrences and regional distributions of 20 antibiotics in water bodies during groundwater recharge

To develop a better understanding of the pollution conditions of antibiotics during the groundwater recharge process, a nation-wide survey was conducted across China for the first time. Overall, 15 recharge sites employing reclaimed water located in different humid, semi-humid and semi-arid regions were selected for analysis of the presence of the 20 most commonly used antibiotics, including tetracyclines (TCs), fluoroquinolones (FQNs), sulfonamides (SAs) and macrolides. All types of antibiotics were detected at concentrations of 212-4035 ng/L in reclaimed water and 19-1270 ng/L in groundwater. FQNs were the predominant antibiotics in reclaimed water samples (38%), followed by SAs (34%). In the SAs group, sulfamethoxazole (SMZ) and sulfamonomethoxine together with trimethoprim accounted for 78% of the total, while ofloxacin (OFL) and norfloxacin accounted for 90% of the FQNs, and doxycycline and oxytetracycline accounted for 82% of the TCs. The concentrations in groundwater were generally 1-2 orders of magnitude lower than in reclaimed water. The three most common antibiotics were OFL, erythromycin (ERY) and SMZ. Similar occurrences of different group antibiotics might be evidence of the influence of groundwater recharge by reclaimed water. FQNs were predominant in northern China, while SAs were predominant in the south. Ecotoxicological risk assessment showed that SMZ, ERY and OFL had the top three hazard quotient values, indicating they should receive preferential treatment before recharging. Overall, these results provide a theoretical basis for development of a recharge standard in China.

Uptake and accumulation of four PPCP/EDCs in two leafy vegetables

Many pharmaceutical and personal care products (PPCPs) and endocrine-disrupting chemicals (EDCs) are present in reclaimed water, leading to concerns of human health risks from the consumption of food crops irrigated with reclaimed water. This study evaluated the potential for plant uptake and accumulation of four commonly occurring PPCP/EDCs, i.e., bisphenol A (BPA), diclofenac sodium (DCL), naproxen (NPX), and 4-nonylphenol (NP), by lettuce (Lactuca sativa) and collards (Brassica oleracea) in hydroponic culture, using (14)C-labeled compounds. In both plant species, plant accumulation followed the order of BPA > NP > DCL > NPX and accumulation in roots was much greater than in leaves and stems. Concentrations of (14)C-PPCP/EDCs in plant tissues ranged from 0.22 ± 0.03 to 927 ± 213 ng/g, but nearly all (14)C-residue was non-extractable. PPCP/EDCs, particularly BPA and NP, were also extensively transformed in the nutrient solution. Dietary uptake of these PPCP/EDCs by humans was predicted to be negligible.

Formation and control of disinfection byproducts and toxicity during reclaimed water chlorination: A review

Chlorination is essential to the safety of reclaimed water; however, this process leads to concern regarding the formation of disinfection byproducts (DBPs) and toxicity. This study reviewed the formation and control strategies for DBPs and toxicity in reclaimed water during chlorination. Both regulated and emerging DBPs have been frequently detected in reclaimed water during chlorination at a higher level than those in drinking water, indicating they pose a greater risk to humans. Luminescent bacteria and Daphnia magna acute toxicity, anti-estrogenic activity and cytotoxicity generally increased after chlorination because of the formation of DBPs. Genotoxicity by umu-test and estrogenic activity were decreased after chlorination because of destruction of toxic chemicals. During chlorination, water quality significantly impacted changes in toxicity. Ammonium tended to attenuate toxicity changes by reacting with chlorine to form chloramine, while bromide tended to aggravate toxicity changes by forming hypobromous acid. During pretreatment by ozonation and coagulation, disinfection byproduct formation potential (DBPFP) and toxicity formation potential (TFP) occasionally increase, which is accompanied by DOC removal; thus, the decrease of DOC was limited to indicate the decrease of DBPFP and TFP. It is more important to eliminate the key fraction of precursors such as hydrophobic acid and hydrophilic neutrals. During chlorination, toxicities can increase with the increasing chlorine dose and contact time. To control the excessive toxicity formation, a relatively low chlorine dose and short contact time were required. Quenching chlorine residual with reductive reagents also effectively abated the formation of toxic compounds.

Molecular characterization of low molecular weight dissolved organic matter in water reclamation processes using Orbitrap mass spectrometry

Reclaimed water has recently become an important water source for urban use, but the composition of dissolved organic matter (DOM) in reclaimed water has rarely been characterized at the compound level because of its complexity. In this study, the transformation and changes in composition of low molecular weight DOM in water reclamation processes, where secondary effluent of the municipal wastewater treatment plant was further treated by biofiltration, ozonation and chlorination, were investigated by "unknown" screening analysis using Orbitrap mass spectrometry (Orbitrap MS). The intense ions were detected over an m/z range from 100 to 450. In total, 2412 formulae with various heteroatoms were assigned, and formulae with carbon (C), hydrogen (H) and oxygen (O) only and C, H, O and sulfur (S) were the most abundant species. During biofiltration, CHO-only compounds with relatively high hydrogen to carbon (H/C) ratio or with saturated structure were preferentially removed, while CHOS compounds were mostly removed. Ozonation induced the greatest changes in DOM composition. CHOS compounds were mostly decreased after ozonation while ozone selectively removed CHO compounds with relatively unsaturated structure and produced compounds that were more saturated and with a higher degree of oxidation. After chlorination, 168 chlorine-containing formulae, chlorinated disinfection by-products (DBPs), were additionally detected. Candidate DBP precursors were determined by tracking chlorinated DBPs formed via electrophilic substitution, half of which were generated during the ozonation.

Impact of reclaimed water irrigation on antibiotic resistance in public parks, Beijing, China

The abundance and distribution of antibiotics and antibiotic resistance genes (ARGs) in soils from six parks using reclaimed water in Beijing, China, were characterized. Three classes of commonly used antibiotics (tetracycles, quinolones, and sulfonamides) were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The highest concentrations of tetracyclines and quinolones were 145.2 μg kg(-1) and 79.2 μg kg(-1), respectively. Detected tetG, tetW, sulI, and sulII genes were quantified by quantitative PCR. ARGs exhibited various abundances for different park soils. The integrase gene (intI1) as an indicator of horizontal gene transfer potential was also detected in high abundance, and had significant positive correlation with tetG, sulI, and sulII genes, suggesting that intI1 may be involved in ARGs dissemination. Both sulII and intI1 clones had high homology with some classes of pathogenic bacteria, such as Klebsiella oxytoca, Acinetobacter baumannii, Shigella flexneri, which could trigger potential public health concern.

Sorption/desorption of non-hydrophobic and ionisable pharmaceutical and personal care products from reclaimed water onto/from a natural sediment

In the present work, the sorption of pharmaceutical and personal care products (PPCPs) (acetaminophen, atenolol, carbamazepine, caffeine, naproxen and sulphamethoxazole) onto the natural organic matter (NOM) and the inorganic surfaces of a natural sandy loam sediment was quantified separately. The quantification was based on the PPCP charge, their degree of ionisation, their octanol-water partitioning coefficient (KOW) and the sediment organic carbon fraction (ƒOC). PPCP desorption from the sediment was examined under conditions of infiltrating water containing a high concentration of inorganic ions (mimicking infiltrating reclaimed water), and a low concentration (and smaller diversity) of inorganic ions (mimicking rainwater infiltration). Batch tests were performed using a sediment/water ratio of 1:4 and a PPCP initial concentration ranging from 1 to 100 μg L(-1). The results showed the type and degree of PPCP ionisation to strongly influence the sorption of these compounds onto the sediment. The sorption of cationic species onto the sediment was higher than that of anionic species and mostly reversible; the sorption of neutral species was negligible. The anionic species sorbed less onto the sediment, but also desorbed less easily. More than 70% of the total sorption was due to interaction with mineral surfaces. This holds especially true for cationic species (atenolol and caffeine) which sorption was enhanced by the negative surface charge of the sediment. The presence of inorganic ions had no impact on the desorption of the PPCPs from the sediment. According to the calculated percentages of removal, the mobility followed the order: carbamazepine>acetaminophen>naproxen>atenolol>sulfamethoxazole>caffeine.

Health risks from exposure to Legionella in reclaimed water aerosols: Toilet flushing, spray irrigation, and cooling towers

The use of reclaimed water brings new challenges for the water industry in terms of maintaining water quality while increasing sustainability. Increased attention has been devoted to opportunistic pathogens, especially Legionella pneumophila, due to its growing importance as a portion of the waterborne disease burden in the United States. Infection occurs when a person inhales a mist containing Legionella bacteria. The top three uses for reclaimed water (cooling towers, spray irrigation, and toilet flushing) that generate aerosols were evaluated for Legionella health risks in reclaimed water using quantitative microbial risk assessment (QMRA). Risks are compared using data from nineteen United States reclaimed water utilities measured with culture-based methods, quantitative PCR (qPCR), and ethidium-monoazide-qPCR. Median toilet flushing annual infection risks exceeded 10^-4 considering multiple toilet types, while median clinical severity infection risks did not exceed this value. Sprinkler and cooling tower risks varied depending on meteorological conditions and operational characteristics such as drift eliminator performance. However, the greatest differences between risk scenarios were due to 1) the dose response model used (infection or clinical severity infection) 2) population at risk considered (residential or occupational) and 3) differences in laboratory analytical method. Theoretical setback distances necessary to achieve a median annual infection risk level of 10^-4 are proposed for spray irrigation and cooling towers. In both cooling tower and sprinkler cases, Legionella infection risks were non-trivial at potentially large setback distances, and indicate other simultaneous management practices could be needed to manage risks. The sensitivity analysis indicated that the most influential factors for variability in risks were the concentration of Legionella and aerosol partitioning and/or efficiency across all models, highlighting the importance of strategies to manage Legionella occurrence in reclaimed water.

Occurrence and risk assessment of pharmaceuticals and personal care products and endocrine disrupting chemicals in reclaimed water and receiving groundwater in China

Groundwater recharge using reclaimed water is considered a promising method to alleviate groundwater depletion. However, pollutants in reclaimed water could be recharged into groundwater during this process, thereby posing a risk to groundwater and human health. In this study, 12 cities in northern China were selected for reclaimed water and groundwater sampling. Analysis of the samples revealed the presence of nine pharmaceutical and personal care products (PPCPs) and five endocrine disrupting compounds (EDCs). In reclaimed water, all the PPCPs and EDCs were found, with sulpiride (SP) and estriol (E3) being most frequently detected. In groundwater samples, only ketoprofen (KP), mefenamic acid (MA), nalidixic acid (NA) and SP were detected among PPCPs, while bisphenol-A (BPA) was dominant among the target EDCs. The risk quotients (RQs) of all target PPCPs and EDCs except 17α-ethinyl estradiol (EE2) and E3 were below 1 in groundwater samples, indicating that EE2 and E3 deserve priority preferential treatment before recharging.

Enhancement of microbial nitrogen removal pathway by vegetation in Integrated Vertical-Flow Constructed Wetlands (IVCWs) for treating reclaimed water

Constructed wetland is an efficient way to lower N load from wastewater treatment plants. Here, the nitrogen removal rate and nitrogen balance, as well as the microbial community structure in IVCWs planted with different vegetation for treating reclaimed water were investigated. The results showed that IVCWs planted with vegetation generally achieved a higher TN removal rate than unplanted treatment, especially for Canna indica L. with 10.35% enhancement. Moreover, the microbial process proportion (83.87-87.94%) is the main N removal pathway in IVCW, and vegetation planting could increase 8.16% of it in average. The combination of quantitative polymerase chain reaction (qPCR) and high-throughput sequencing analysis revealed that IVCW planted with Canna indica L. showed the highest microbial abundant and biodiversity. The related denitrification genus Pseudomonas, Acinetobacter, Rhizobium, Bacillus and Rhodopseudomonas might be responsible for the high biological removal rate of nitrogen.

Differences in dissolved organic matter between reclaimed water source and drinking water source

Dissolved organic matter (DOM) significantly affects the quality of reclaimed water and drinking water. Reclaimed water potable reuse is an effective way to augment drinking water source and de facto reuse exists worldwide. Hence, when reclaimed water source (namely secondary effluent) is blended with drinking water source, understanding the difference in DOM between drinking water source (dDOM) and reclaimed water source (rDOM) is essential. In this study, composition, transformation, and potential risk of dDOM from drinking water source and rDOM from secondary effluent were compared. Generally, the DOC concentration of rDOM and dissolved organic nitrogen (DON) content in reclaimed water source were higher but rDOM exhibited a lower aromaticity. Besides, rDOM comprises a higher proportion of hydrophilic fractions and more low-molecular weight compounds, which are difficult to be removed during coagulation. Although dDOM exhibited higher specific disinfection byproducts formation potential (SDBPFP), rDOM formed more total disinfection byproducts (DBPs) during chlorination including halomethanes (THMs) and haloacetic acids (HAAs) due to high DOC concentration. Likewise, in consideration of DOC basis, rDOM contained more absolute assimilable organic carbon (AOC) despite showing a lower specific AOC (normalized AOC per unit of DOC). Besides, rDOM exhibited higher biotoxicity including genotoxicity and endocrine disruption. Therefore, rDOM presents a greater potential risk than dDOM does. Reclaimed water source needs to be treated carefully when it is blended with drinking water source.

Ecological risk of estrogenic endocrine disrupting chemicals in sewage plant effluent and reclaimed water

The long-term ecological risk of micropollutants, especially endocrine disrupting chemicals (EDCs) has threatened reclaimed water quality. In this study, estrogenic activity and ecological risk of eight typical estrogenic EDCs in effluents from sewage plants were evaluated. The estrogenic activity analysis showed that steroidal estrogens had the highest estrogenic activity (ranged from 10(-1) to 10(3) ng-E2/L), phenolic compounds showed weaker estrogenic activity (mainly ranged from 10(-3) to 10 ng-E2/L), and phthalate esters were negligible. The ecological risk of the estrogenic EDCs which was characterized by risk quotient ranged from 10(-4) to 10(3), with an order in descending: steroids estrogens, phenolic compounds and phthalate esters. The eight estrogenic EDCs were scored and sorted based on the comparison of the estrogenic activity and the ecological risk, suggesting that 17α-ethynylestradiol (EE2), estrone (E1) and estradiol (E2) should be the priority EDCs to control in municipal sewage plants.

Impacts of reclaimed water irrigation on soil antibiotic resistome in urban parks of Victoria, Australia

The effluents from wastewater treatment plants have been recognized as a significant environmental reservoir of antibiotics and antibiotic resistance genes (ARGs). Reclaimed water irrigation (RWI) is increasingly used as a practical solution for combating water scarcity in arid and semiarid regions, however, impacts of RWI on the patterns of ARGs and the soil bacterial community remain unclear. Here, we used high-throughput quantitative PCR and terminal restriction fragment length polymorphism techniques to compare the diversity, abundance and composition of a broad-spectrum of ARGs and total bacteria in 12 urban parks with and without RWI in Victoria, Australia. A total of 40 unique ARGs were detected across all park soils, with genes conferring resistance to β-lactam being the most prevalent ARG type. The total numbers and the fold changes of the detected ARGs were significantly increased by RWI, and marked shifts in ARG patterns were also observed in urban parks with RWI compared to those without RWI. The changes in ARG patterns were paralleled by a significant effect of RWI on the bacterial community structure and a co-occurrence pattern of the detected ARG types. There were significant and positive correlations between the fold changes of the integrase intI1 gene and two β-lactam resistance genes (KPC and IMP-2 groups), but no significant impacts of RWI on the abundances of intI1 and the transposase tnpA gene were found, indicating that RWI did not improve the potential for horizontal gene transfer of soil ARGs. Taken together, our findings suggested that irrigation of urban parks with reclaimed water could influence the abundance, diversity, and compositions of a wide variety of soil ARGs of clinical relevance.

ONE-SENTENCE SUMMARY

Irrigation of urban parks with treated wastewater significantly increased the abundance and diversity of various antibiotic resistance genes, but did not significantly enhance their potential for horizontal gene transfer.

Detection of vancomycin-resistant enterococci (VRE) at four U.S. wastewater treatment plants that provide effluent for reuse

Vancomycin-resistant enterococci (VRE), a leading cause of hospital-acquired infections, can occur in wastewater. However, to date, no previous studies have evaluated the occurrence of VRE at wastewater treatment plants (WWTPs) that send their treated effluent to reuse sites. We evaluated the occurrence, concentration, and antimicrobial resistance patterns of VRE at U.S. WWTPs associated with reuse sites. We collected 44 wastewater samples, representing treatment steps from influent to effluent, from two Mid-Atlantic and two Midwest WWTPs between October 2009 and October 2010. Samples were analyzed for total enterococci and VRE using membrane filtration. Isolates were confirmed using biochemical tests and PCR. Antimicrobial susceptibility testing was performed by Sensititre microbroth dilution. Data were analyzed by two-sample proportion tests and analysis of variance. We detected VRE in 27% (12/44) of all wastewater samples collected and VRE represented 3% of total enterococci detected at all WWTPs. More samples were VRE-positive from the Mid-Atlantic compared to the Midwest WWTPs (p=0.008). VRE concentrations decreased as treatment progressed at all WWTPs, except at Mid-Atlantic WWTP1 where there was an increase in VRE concentrations in activated sludge reactor samples. VRE were not detected in chlorinated effluent, but were detected in one un-chlorinated effluent sample. All unique VRE isolates were multidrug resistant. Fifty-five percent (12/22) of the isolates displayed high-level aminoglycoside resistance. Our findings show that chlorination reduces the occurrence of VRE in wastewater. However, WWTP workers could be exposed to VRE during wastewater treatment. Our data also raise potential concerns about VRE exposure among individuals who come into contact with un-chlorinated reclaimed water.

The utilization of reclaimed water: Possible risks arising from waterborne contaminants

Increasing interest of seeking substitutable water resources accrues from shortage of freshwater. One of the options considered is reclaimed water (also designated as recycled water) that has been widely used in daily life. Although reclaimed water can serve as a feasible reliever of water pressure, attention about its technologies and potential risks is growing in the meantime. Most established wastewater treatment plants (WWTPs) predate many new contaminants, which means treatment processes cannot ensure to dislodge certain contaminants completely from origin water. Furthermore, a wide range of factors, such as seasons and influent variations, affect occurrence and concentration of reclaimed water-borne contaminants, making research about quality of reclaimed water especially significant. Many reclaimed water-borne contaminants, including biological and chemical contaminants, are toxic to human health, and complex wastewater matrix may aggravate water quality of concern. The widespread use of reclaimed water continues to be a concern on agriculture, ecological environment and human health. This study aims to: 1) provide a critical review about occurrence and profiles of diverse contaminants in the treated reclaimed water, 2) discuss the possibility to avoid the secondary pollution in reuse of reclaimed water, and 3) reveal the prospective consequences of using reclaimed water on agriculture, ecological environment and human health.

Occurrence and risk assessment of emerging contaminants in a water reclamation and ecological reuse project

Water reclamation and ecological reuse is gradually becoming a popular solution to address the high pollutant loads and insufficient ecological flow of many urban rivers. However, emerging contaminants in water reuse system and associated human health and ecological risks need to be assessed. This study determined the occurrence and human health and ecological risk assessments of 35 emerging contaminants during one year, including 5 types of persistent organic pollutants (POPs), 5 pharmaceutical and personal care products (PPCPs), 7 endocrine disrupting chemicals (EDCs) and 18 disinfection by-products (DBPs), in a wastewater treatment plant (WWTP) and receiving rivers, as well as an unimpacted river for comparison. Results showed that most of PPCPs and EDCs, especially antibiotics, triclosan, estrogens and bisphenol A, occurred frequently at relatively high concentrations, and they were removed from 20.5% to 88.7% with a mean of 58.9% via WWTP. The highest potential noncarcinogenic and carcinogenic risks in different reuse scenarios were assessed using maximal detected concentrations, all below the acceptable risk limits, with the highest total combined risk value of 9.21 × 10^-9 and 9.98 × 10^-7, respectively. Ecological risk assessment was conducted using risk quotient (RQ) method and indicated that several PPCPs, EDCs and haloacetonitriles (HANs) pose high risk (RQ > 1) to aquatic ecology in the rivers, with the highest RQ up to 83.8. The study suggested that ecological risks need to be urgently addressed by updating and optimizing the process in WWTPs to strengthen the removal efficiencies of emerging contaminants. The study can serve as a reference for safer water reuse in the future, while further studies could be conducted on the health risk of specific groups of people, exposure parameters in water reuse, as well as more emerging contaminants.

Fates and transport of PPCPs in soil receiving reclaimed water irrigation

Fates and transport of 9 commonly found PPCPs of the reclaimed water were simulated based on the HYDRUS-1D software that was validated with data generated from field experiments. Under the default scenario in which the model parameters and input data represented the typical conditions of turf grass irrigation in southern California, the adsorption, degradation, and volatilization of clofibric acid, ibuprofen, 4-tert-octylphenol, 4-n-nonylphenol, naproxen, triclosan, diclofenac sodium, bisphenol A and estrone in the receiving soils were tracked for 10 years. At the end, their accumulations in the 90 cm soil profile varied from less than 1 ng g(-1) to about 140 ng g(-1) and their concentrations in the drainage water in the 90 cm soil depth varied from nil to μg L(-1) levels. The adsorption and microbial degradation processes interacted to contain the PPCPs entirely within surface 40 cm of the soil profiles. Leaching and volatilization were not significant processes governing the PPCPs in the soils. The extent of accumulations in the soils did not appear to produce undue ecological risks to the soil biota. PPCPs did not represent any potential environmental harm in reclaimed water irrigation.

Pharmaceuticals and pesticides in reclaimed water: Efficiency assessment of a microfiltration-reverse osmosis (MF-RO) pilot plant

Water reuse is becoming a common practice in several areas in the world, particularly in those impacted by water scarcity driven by climate change and/or by rising human demand. Since conventional wastewater treatment plants (WWTPs) are not able to efficiently remove many organic contaminants and pathogens, more advanced water treatment processes should be applied to WWTP effluents for water reclamation purposes. In this work, a pilot plant based on microfiltration (MF) followed by reverse osmosis (RO) filtration was applied to the effluents of an urban WWTP. Both the WWTP and the pilot plant were investigated with regards to the removal of a group of relevant contaminants widely spread in the environment: 28 pharmaceuticals and 20 pesticides. The combined treatment by the MF-RO system was able to quantitatively remove the target micropollutants present in the WWTP effluents to values either in the low ng/L range or below limits of quantification. Monitoring of water quality of reclaimed water and water reclamation sources is equally necessary to design the most adequate treatment procedures aimed to water reuse for different needs.

Performance of wastewater reclamation systems in enteric virus removal

Analysis of virus removal by tertiary or advanced sewage treatment processes is an emerging topic due to importance of reusing water on a global level. This study aimed to monitor important human viral pathogens: the human adenovirus (HAdV), JC polyomavirus (JCV) and Species A rotaviruses (RVA) in urban sewage, secondary effluents and reclaimed water from metropolitan São Paulo (MSP), Brazil. Four large wastewater treatment plants (WWTPs) in MSP were sampled monthly during a one-year period (April 2015 to March 2016). The viruses were quantified by quantitative PCR (qPCR), and HAdV viability was tested by the integrated cell culture (ICC)-qPCR assay. WWTPs are composed of activated sludge processes and different tertiary treatments (coagulation/sedimentation, sand-anthracite filters, membrane bioreactors (MBRs)/reverse osmosis (RO) and disinfection by chlorination). Physicochemical parameters were also evaluated to verify association with density of viruses detected in different treatment stages. HAdV, JCV and RVA were consistently detected (100%) in the sewage influent samples (range: 10⁶-10⁸ genome copies GC/L). In the secondary effluent, HAdV was detected in 100% (48/48) of the analysed samples, JCV in 85.4% and RVA in 97.9% (range: 10⁴-10⁷ GC/L for all viruses tested). HAdV was the most frequently detected virus in the tertiary effluent (62.2%) (28/45), exhibiting a viability between 0 and 44% of the tested samples in the wastewater reclamation systems. The MBR/RO systems demonstrated better virus removal efficiencies (range: 2.3-2.9 log₁₀). Temperature, pH, turbidity and total organic carbon presented association with the viral density in the reclaimed water samples. Presence of viruses in treated effluents can indicates health risks depending on uses of recovery water. Further risk assessment studies should be conducted to better assess health risks under different exposure scenarios for water recovery in urban settings.

Accumulation of contaminants of emerging concern in food crops-part 1: Edible strawberries and lettuce grown in reclaimed water

Contaminants of emerging concern present in domestic waste streams include a highly diverse group of potentially biologically active compounds that can be detected at trace levels in wastewater. Concerns about potential uptake into crops arise when reclaimed water is used in food crop production. The present study investigated how 9 contaminants of emerging concern in reclaimed water are taken up into edible portions of two food crops. Two flame retardant chemicals, tris(1-chloro-2-propyl) phosphate (TCPP) and tris(2-chloroethyl) phosphate (TCEP) and several polar pharmaceuticals (carbamazepine, diphenhydramine, sulfamethoxazole, and trimethoprim) accumulated in a linear, concentration-dependent manner in lettuce (Lactuca sativa) irrigated with reclaimed water, suggesting passive uptake of both neutral and ionizable chemical contaminants in lettuce. Furthermore, concentration-dependent accumulation of TCEP and TCPP from reclaimed water was also observed in strawberry fruits (Fragaria ananassa). Collectively, these data suggest that highly polar or charged contaminants can be taken up by crops from water bearing contaminants of emerging concern and can be accumulated in the edible portions. Using these data, however, estimates of human exposure to these contaminants from reclaimed water food crop accumulation suggest that exposure to the contaminants of emerging concern examined in the present study is likely substantially lower than current exposure guidelines.

Effects of chlorination/chlorine dioxide disinfection on biofilm bacterial community and corrosion process in a reclaimed water distribution system

In this work, reclaimed water treated with sodium hypochlorite (NaClO) or chlorine dioxide (ClO₂) at 1, 2, and 4 mg/L was operated successively for 30 days respectively, in annular reactors with new cast iron coupons, corresponding to stages I (days 0-30), II (days 31-60), and III (days 61-90). The Illumina HiSeq 2500 sequencing platform was used to analyze the bacterial community composition, scanning electron microscopy and X-ray diffraction analyses were conducted to characterize corrosion scales, and the weight loss method was served to determine the general corrosion rate. Results reveal the precise disinfection effect on biofilm bacteria to be dose dependent and species specific. In stage I, disinfection caused a reduction in the number of operational taxonomic units, but, had little effect on biofilm composition. In stage II, NaClO and ClO₂ induced a reduction of Proteobacteria proportion, but increased the dominance of Firmicutes; the diminished Proteobacteria in NaClO test mainly included Gammaproteobacteria, while, that in ClO₂ test mainly included the Gammaproteobacteria and Betaproteobacteria. In stage III, Firmicutes presented a certain resistance to NaClO and ClO₂ as the accumulation of corrosion scales. Results also indicated that disinfection enhanced the corrosion process, and the promoting effect of ClO₂ was more pronounced than that of NaClO. Moreover, this promoting effect was more obvious in stage I than that in the latter two stages. The strong oxidization effect associated with disinfection in stage I was the dominant factor promoting corrosion, whereas, the bacterial community also played a crucial role in stages II and III.

Accumulation of contaminants of emerging concern in food crops-part 2: Plant distribution

Arid agricultural regions often turn to using treated wastewater (reclaimed water) to irrigate food crops. Concerns arise, however, when considering the potential for persistent contaminants of emerging concern to accumulate into plants intended for human consumption. The present study examined the accumulation of a suite of 9 contaminants of emerging concern into 2 representative food crops, lettuce and strawberry, following uptake via the roots and subsequent distribution to other plant tissues. Calculating accumulation metrics (concentration factors) allowed for comparison of the compartmental affinity of each chemical for each plant tissue compartment. The root concentration factor was found to exhibit a positive linear correlation with the pH-adjusted octanol-water partition coefficient (DOW ) for the target contaminants of emerging concern. Coupled with the concentration-dependent accumulation observed in the roots, this result implies that accumulation of these contaminants of emerging concern into plant roots is driven by passive partitioning. Of the contaminants of emerging concern examined, nonionizable contaminants, such as triclocarban, carbamazepine, and organophosphate flame retardants displayed the greatest potential for translocation from the roots to above-ground plant compartments. In particular, the organophosphate flame retardants displayed increasing affinity for shoots and fruits with decreasing size/octanol-water partition coefficient (KOW ). Cationic diphenhydramine and anionic sulfamethoxazole, once transported to the shoots of the strawberry plant, demonstrated the greatest potential of the contaminants examined to be then carried to the edible fruit portion.

Occurrence and fate of antibiotics and heavy metals in sewage treatment plants and risk assessment of reclaimed water in Chengdu, China

Aim of this study was to provide an up-to-date assessment of the heavy metals and antibiotics in reclaimed water in Chengdu, China. 3 sewage treatment plants (STPs) and 1 constructed wetland (CW) were first taken as the research objects. The total concentration and reduction change rule of heavy metals and antibiotics in the process of reclaimed water production were investigated. The possible health risks to ecological environment and human body were evaluated. For the treatment process, the Cyclic Activated Sludge System (CASS) used in A sewage treatment plant (STP A) had the best removal effect for heavy metals. When the proportion of industrial wastewater in the influent was relatively high, the heavy metal pollution level was alert. Ofloxacin (OFX) and roxithromycin (ROX) were the most abundant antibiotics in reclaimed water. After being removed by the sewage treatment system, OFX concentrations changed, but several of them remained in reclaimed water. Negative removal of ROX occurred. This is because macrolides were wrapped in human feces, whose concentration increased as feces disperse and hydrolyze. Compared with CASS (20.02%) and Anaerobic-Anoxic-Oxic process (A²/O 34.16%), the average removal rate of antibiotics from the A²/O accompanied by Membrane Bio-Reactor (71.1%) and CW (54.95%) was higher. When the proportion of domestic sewage in wastewater was high, antibiotics in reclaimed water had higher ecological risk. OFX had the highest ecological risk for non-target aquatic organisms. It was assessed that the heavy metals and antibiotics studied did not pose a carcinogenic or non-carcinogenic risk to human health.

Effect of tetracycline on the growth and nutrient removal capacity of Chlamydomonas reinhardtii in simulated effluent from wastewater treatment plants

The aim of this work was to study the effect of tetracycline, which is on the growth, physiological characteristics, and contaminants removal by Chlamydomonas reinhardtii. The results showed that the biomass and photosynthetic pigment concentration of C. reinhardtii exposed to tetracycline were lower than those of the control, while the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities, and the malondialdehyde (MDA) content, were higher than those of the control. Additionally, when the tetracycline concentration reached 0.25mg/L, the removal of total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD) decreased from 80.8 to 55.0%, 100 to 92.5%, and 36.5 to 11.5%, respectively. Thus, tetracycline concentrations of 0-0.25mg/L are expected to have a significant effect on the growth and nutrient removal of C. reinhardtii in recycled water from wastewater treatment plants.