Occurrence, Profile, and Potential Risks of Novel and Legacy Polyfluoroalkyl Substances in Bullfrogs: Pilot Study in an Intensive Aquaculture Region, China

Per- and polyfluoroalkyl substances (PFASs) have captured worldwide attention due to their persistent and bioaccumulative characteristics. The bullfrog is a highly nutritious and edible aquatic product, but the PFAS accumulation characteristics of bullfrogs had not been paid attention. The present study analyzed the PFAS concentrations in different tissues of cultured bullfrogs and relevant water and sediments collected from the aquaculture region in the coastal area of South China. Results showed that total PFAS concentrations were 50.26–364.25 ng/L in water, with a mean of 135.58 ng/L; concentrations in effluent water were significantly higher than those in influent water, which means bullfrog farming could increase contaminants into the surroundings. The total PFAS concentrations varied from 2.89 to 162.26 ng/g·dw in sediment. The distribution profile of PFASs in sediment was similar to that of water, with short chain playing a significant role. Total PFASs in bullfrog tissues were 3.36–84.07 ng/g·dw, with the highest values in the digestive system (intestines and stomach). As for one novel PFAS alternative, chlorinated polyfluorinated ether sulfonate (F-53B) was found at high detectable levels in all habitat samples and had a higher value of logarithmic bioaccumulation factors. The estimated dietary intake (EDI) for residents in the study area was generally higher than that in other regions; however, the hazard ratios (HRs) for most detected PFASs were far below the safety threshold value “1.” These results suggest that frequent consumption of these bullfrogs would basically not cause severe health effects on local residents in terms of PFASs.

Induced Bank Filtration: Hydraulic Testing of Pilot Filters

Hydraulic tests were performed on two pilot scale filters as part of a water treatment project in the village of Nersa, Karnataka, India. The filters use locally sourced alluvial material to filter E.coli contamination using natural processes that mimic those in Riverbank Filtration (RBF). Two pilot scale filters were tested, one containing locally sourced granular activated carbon (GAC) and one without. A falling head test and tracer test were preformed, and breakthrough curves were used to analyze the hydraulic performance. E.coli data were also collected, and percent removal was calculated to determine the effectiveness of the filters. Relative to the influent water, the E.coli removal percentage of Filter 1 (no GAC) was consistently high and ranged between 97.1% and 100% E.coli. The addition of GAC did not improve performance in this study. Overall, the effectiveness in bacteria removal observed in the non GAC filter warranted construction of a full-scale system.

Electrochemical Removal of Cesium Ions via Capacitive Deionization Using an Ion-Exchange Layer Coated on a Carbon Electrode

This study was conducted to evaluate the feasibility of using electrosorption to remove cesium (Cs+) ions from aqueous solutions using the membrane capacitive deionization (MCDI) process. The electrochemical properties were analyzed using cyclic voltammetry (CV) and impedance spectroscopy (EIS). The activated carbon electrode coated by a polymer layer showed higher specific adsorption capacity (SAC) and removal efficiency of Cs+ than the AC electrode. The effects of potential, flow rate, initial Cs+ concentration, and pH values were investigated to optimize the electrosorption performance. The electrosorption capacity increased with an increase in the applied potential and the concentration of Cs+ in the influent water. The pH value is an important parameter on electrosorption performance. The removal of Cs+ ions was affected by the pH of the influent water because H+ ions acted as competing ions during the electrosorption process. Cs+ was preferentially adsorbed to the electrode in the early stages of adsorption but was later replaced by H+. A higher presence of H+ ions could reduce the adsorption capacity of Cs+ ions. The ion-exchange layer coated AC electrode was shown to be favorable for the removal of Cs+, despite the limited electrosorption ability in a highly acidic solution.

Escherichia coli Reduction in Water by Zero-Valent Iron–Sand Filtration Is Based on Water Quality Parameters

Improving the microbial quality of agricultural water through filtration can benefit small farms globally. The incorporation of zero-valent iron (ZVI) into sand filters (ZVI–sand) has been effective in reducing E. coli, Listeria spp., and viruses from agricultural water. This study evaluated ZVI–sand filtration in reducing E. coli levels based on influent water type and the percentage of ZVI in sand filters. A ZVI–sand filter (50% ZVI/50% sand) significantly (p < 0.001) reduced E. coli levels in deionized water by more than 1.5 log CFU/mL compared to pond water over six separate trials, indicating that water type impacts E. coli removal. Overall reductions in E. coli in deionized water and pond water were 98.8 ± 1.7% and 63 ± 24.0% (mean ± standard deviation), respectively. Filters constructed from 50% ZVI/50% sand showed slightly more reduction in E. coli in pond water than filters made from a composition of 35% ZVI/65% sand; however, the difference was not statistically significant (p = 0.48). Principal component analysis identified that the turbidity and conductivity of influent water affected E. coli reductions in filtered water in this study. ZVI–sand filtration reduces Escherichia coli levels more effectively in waters that contain low turbidity values.

Pollution Characteristics and Emissions of Typical Organophosphate Esters From a Wastewater Treatment Plant in Chengdu, China

Effluent from wastewater treatment plants (WWTP) is an important source of organophosphate esters (OPEs) in the receiving rivers. In this paper, the concentration and distribution of seven OPEs in the water samples were determined, and the discharge was estimated. The results showed that the total removal rate of Σ7OPEs in water phase in WWTP was 57.2%. The average concentrations of Σ7OPEs in influent and effluent of the WWTP during rainy period were 3956.1 ± 1897.3 ng/L and 1461.9 ± 846.3 ng/L, respectively, which were about 4 times larger than those in influent water (978.2 ± 166.5 ng/L) and effluent (418.3 ± 12.0 ng/L) during non-rainy period, indicating that rainfall has a marked impact on the load of OPEs in WWTP and the receiving water. It was estimated that the average daily discharge of Σ7OPEs in the effluent of WWTP was 157.9 g, and the daily per capita contribution of the population in the area to the OPEs in the influent was 0.414 mg. During the shift of labour-intensive manufacturing from the coastal developed areas to inland regions, OPEs were widely used and produced in Southwest China. The total amount of OPEs emissions and its control should be taken into consideration.

Laboratory Efficacy of Locally Available Backwashing Methods at Removing Fouling in Hollow-Fiber Membrane Filters Used for Household Water Treatment

Hollow-fiber membrane filters (HFMFs) for household water treatment (HWT) can efficaciously remove disease-causing organisms in laboratory settings. However, lower effectiveness in use in low- and middle-income countries (LMICs) and humanitarian contexts (HCs) has been observed and attributed to membrane fouling and the associated cleaning. In LMICs/HCs, it is not possible to prevent and control fouling using commonly known methods (e.g., testing influent water, maintenance regimes), and the literature on fouling/cleaning of HFMFs distributed in LMICs is scarce. As such, controlled laboratory experiments were conducted to determine the efficacy of locally available (in LMICs/HCs) backwashing solutions at removing fouling using different influent waters and HFMF types. Four commonly distributed HFMFs were selected; fouling layers were developed by filtering three influent water compositions, representing LMIC/HC waters, for 10-days, and bleach, water, or vinegar backwashing solutions were used for daily backwashing. Filter performance indicators included: fiber mechanical properties (strain at break, break force), water quantity performance (flow), water quality performance (turbidity, E. coli), and imaging. The study found fouling developed rapidly and altered mechanical properties and water quantity indicators within 200 hours of filtration. Fouling did not decrease water quality indicators. Backwashing improved the filter’s mechanical properties and water quantity performance, but it did not fully recover the initial performance. Additionally, recovery differed between backwashing solutions, and no universal cleaning recommendation appropriate for HFMFs in LMICs/HCs was identified. Overall, fouling development and control depended on HFMF type, influent water quality, and backwashing solution type; thus, caution before distributing HFMFs for long-term use in LMICs/HCs is recommended.

An innovative compound bed of EDI device with enhancing ion-exchange resins regeneration efficiency

Electrodeionization (EDI) technology is limited by low regeneration efficiency of ion exchange resins, requirements of high-quality influent water, fouling of ion exchange membrane and electrode, etc. In this work, a novel bed type called compound bed that cation and anion exchange resins were near the cation and anion exchange membrane were placed in layers, was proposed to implement high-efficiency regeneration of ion exchange resins. The influence of different operating conditions on the regeneration efficiency of ion exchange resins was elucidated as well. The regeneration efficiency of ion exchange resins could reach 73.1%, when the device was operated for 5 h under current density of 9 mA/cm2, cation and anion exchange resins ratio of 2: 3, influent water conductivity of 1,360 μS/cm and hardness of 400 mg/L. Therefore, the proposed compound bed structure not only widened the inlet water conditions, but also achieved the high-efficiency regeneration of ion exchange resins and anti-fouling of membranes and electrodes.

Inhibition of staphylococci and S. aureus in wastewater by ferrates and electrochemical methods

Increasing concentration of antibiotics in environment and their subinhibitory concentrations in wastewater may result in increased antibiotic resistance of present bacteria. Therefore, this study was aimed to analyze the efficiency of coagulase-positive staphylococci and Staphylococcus aureus inhibition in wastewater by electrochemical methods and addition of ferrates. Advanced electrochemical oxidation by boron doped diamond electrodes in anode; cathode and anode-cathode connection were used for wastewater disinfection. Results showed that the most effective connection was the anodic one, as complete inhibition of coagulase-positive staphylococci as well as of S. aureus was observed after 40 min. Energy consumption was 3.69 kWh/m3 for effluent wastewater disinfection. The second studied method of wastewater disinfection was the application of powdered ferrates. Addition of 100 mg of ferrates resulted in the inhibition of 84—96 % of coagulase-positive staphylococci and 97—99 % of S. aureus in influent water, while the inhibition of coagulase-positive staphylococci and S. aureus was 61—83 % and 83—86 %, respectively, in effluent wastewater.

Pilot-scale study of forward osmosis for treating desulfurization wastewater

Forward osmosis (FO) treatment of desulfurization wastewater shows great potential in laboratory scale tests. To explore the adaptability of the forward osmosis system in the practical treatment of desulfurization wastewater, we carried out a pilot test on desulfurization wastewater treated by the traditional method under the conditions of adding soda ash (SA) and adding FO scale inhibitor (FOSI). The results showed that the FO system could concentrate desulfurization wastewater with an average TDS of 15,816–32,820 mg/L in the influent water to an average TDS of more than 120,000 mg/L, which was concentrated 3.8–7.8 times. The removal rates of Ca2+, Mg2+ and Cl− were more than 99% and the system could operate stably for a long time. Under the condition of adding SA and FOSI, the system recovery rate was 85.38% and 73.02%, respectively. The operating cost was 25 RMB/ton and 21.77 RMB/ton, respectively. The results showed that the application of forward osmosis in desulfurization wastewater treatment was technically feasible and economically effective.

SARS-CoV-2 RNA titers 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 tested using a porcine coronavirus (Porcine Epidemic Diarrhea Virus, PEDV) and mengovirus (MgV). The procedure resulted in average recoveries of 10.90 ± 3.54% and 10.85 ± 2.11% in influent water and 3.29 ± 1.58% and 6.19 ± 1.00% in effluent water 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 waters of 5.38 ± 0.21 log 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 SARS-CoV-2 was circulating among the population 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.