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Background: Wastewater-based epidemiology (WBE) surveillance as an early warning system (EWS) for monitoring community transmission of SARS-CoV-2 in low- and middle-income country (LMIC) settings, where diagnostic testing capacity is limited, needs further exploration. We explored the feasibility to conduct a WBE surveillance in Indonesia, one of the global epicenters of the COVID-19 pandemic in the middle of 2021, with the fourth largest population in the world where sewer and non-sewered sewage systems are implemented. The feasibility and resource capacity to collect samples on a weekly or fortnightly basis with grab and/or passive sampling methods, as well as to conduct qualitative and quantitative identification of SARS-CoV-2 ribonucleic acid (RNA) using real-time RT-PCR (RT-qPCR) testing of environmental samples were explored. Materials and methods: We initiated a routine surveillance of wastewater and environmental sampling at three predetermined districts in Special Region of Yogyakarta Province. Water samples were collected from central and community wastewater treatment plants (WWTPs), including manholes flowing to the central WWTP, and additional soil samples were collected for the near source tracking (NST) locations (i.e., public spaces where people congregate). Results: We began collecting samples in the Delta wave of the COVID-19 pandemic in Indonesia in July 2021. From a 10-week period, 54% (296/544) of wastewater and environmental samples were positive for SARS-CoV-2 RNA. The sample positivity rate decreased in proportion with the reported incidence of COVID-19 clinical cases in the community. The highest positivity rate of 77% in week 1, was obtained for samples collected in July 2021 and decreased to 25% in week 10 by the end of September 2021. Conclusion: A WBE surveillance system for SARS-CoV-2 in Indonesia is feasible to monitor the community burden of infections. Future studies testing the potential of WBE and EWS for signaling early outbreaks of SARS-CoV-2 transmissions in this setting are required. [ABSTRACT FROM AUTHOR]

Current commercial sensors to monitor water flow velocities are expensive, bulky, and require significant effort to install. Low-cost sensors open the possibility of monitoring storm and waste water systems at a much greater spatial and temporal resolution without prohibitive costs and resource investment. To aid in this, this work developed a low-cost, low-power velocity sensor based on acoustic Doppler velocimetry. The sensor, costing less than 50 USD is open-source, open-hardware, compact, and easily interfaceable to a wide range of data-logging systems. A freely available sensor design at this price point does not currently exist, and its novelty is in enabling high-resolution real-time monitoring schemes. The design is capable of measuring water velocities up to 1200 mm/s. The sensor is characterised and then verified in an in-field long-term test. Finally, the data from this test are then used to evaluate the performance of the sensor in a real-world scenario. The analysis concludes that the sensor is capable of effectively measuring water velocity. [ABSTRACT FROM AUTHOR]

Wastewater-based surveillance is emerging as an important tool for the COVID-19 pandemic trending. Current methods of wastewater collection, such as grab and auto-composite sampling, have drawbacks that impede effective surveillance, especially from small catchments with limited accessibility. Passive samplers, which are more cost-effective and require fewer resources to process, are promising candidates for monitoring wastewater for SARS-CoV-2. Here, we compared traditional auto sampling with passive sampling for SARS-CoV-2 detection in wastewater. A torpedo-style 3D-printed passive sampler device containing both cotton swabs and electronegative filter membranes was used. Between April and June 2021, fifteen passive samplers were placed at a local hospital's wastewater outflow alongside an autosampler. Reverse transcription and quantitative polymerase chain reaction (RT-qPCR) was used to detect SARS-CoV-2 in the samples after processing and RNA extraction. The swab and membrane of the passive sampler showed similar detection rates and cycle threshold (Ct) values for SARS-CoV-2 RNA for the N1 and N2 gene targets. The passive method performed as well as the grab/auto sampling, with no significant differences between N1 and N2 Ct values. There were discrepant results on two days with negative grab/auto samples and positive passive samples, which might be related to the longer duration of passive sampling in the study. Overall, the passive sampler was rapid, reliable, and cost-effective, and could be used as an alternative sampling method for the detection of SARS-CoV-2 in wastewater. [ABSTRACT FROM AUTHOR]

Stormwater biofilters have shown promising yet variable removal of faecal microorganisms. The effects of vegetation, filter media and extended drying on the removal of Escherichia coli are investigated in the current study. Semi-synthetic stormwater was applied to 25 biofilters representing five different design configurations, all of which contained a submerged zone (SZ). The influence of extended dry periods on E. coli removal depended on the presence/absence of vegetation. Uptake of SZ water by plants with extensive roots during the dry periods lead to deterioration of the subsequent outflow water quality compared to unvegetated biofilters. Without a significant loss of SZ volume, a loamy sand biofilter planted with either Carex appressa or Leptospermum continentale can achieve a higher removal performance than an unvegetated washed sand biofilter. However, in warmer climates that experience long dry weather periods, and inability to control SZ volumes, un-vegetated columns may result in lower effluent E. coli concentrations. [ABSTRACT FROM AUTHOR]

This study proposes a new stormwater biofilter validation approach, using a process-based model of micropollutant removal in stormwater biofilters. The model performance was assessed against in-situ challenge tests conducted on a field biofilter under challenging operational conditions for removing four herbicides (atrazine, simazine, prometryn and glyphosate). Two-site adsorption kinetics were used on the laboratory results to estimate parameters; the estimated Koc (soil organic carbon-water partitioning coefficient) corresponded well with literature values, while fe (instantaneous adsorption fraction) and αk (kinetic adsorption rate) differed from the literature. The agreement between modelled outflow concentrations and in-situ challenge tests was good for prometryn (Nash-Sutcliffe coefficient, E = 0.60) and moderate for glyphosate (E = 0.45), with up to 20% over-prediction of peak outflow concentrations. Poor performance were found for atrazine and simazine (E = 0.30). The prediction uncertainties were bigger after long dry periods, which was attributed to complex processes (biodegradation and evaporation) not captured in either the laboratory column experiments or the model. [ABSTRACT FROM AUTHOR]

• Significant research underpins stormwater treatment using passive biotechnologies. • Recent advances in media amendment, antimicrobial plants and technology application. • Fit-for-purpose water production requires consistent and reliable performance. • Solid foundations exist but natural and passive systems are intrinsically variable. • Need for robust validation, real-time control and monitoring, and tighter standards. Biotreatment technologies offer many advantages for passive stormwater treatment before harvesting, but performance can be variable and sensitive to system design, construction, operation and maintenance. While there is substantial research underpinning pollutant removal, hydraulic function, internal processes and optimal design, specific focus upon stormwater harvesting is relatively limited. Recent advances in system design include testing media amendments for targeted pollutant removal, enhanced pathogen removal using antimicrobial plants, and broadening technology application. However, the production of reliable fit-for-purpose water requires the development of robust validation methodologies to meet public safety expectations. While foundation studies exist, more needs to be done to extend the validation framework, monitor and control system performance and operation in real-time, and apply standards and regulatory checks. [ABSTRACT FROM AUTHOR]

Electrochemical oxidation (ECO) has shown good potential for disinfection of wastewater discharges but has not been tested for stormwater. Due to far lower salinity and chloride levels present in stormwater than in wastewaters, the knowledge so far on the ECO disinfection performance cannot simply be used for stormwater applications. This paper presents the first study on the feasibility of ECO technology for disinfection of pre-treated stormwater. Disinfection performance of E. coli was tested using a dimensional stable anode (DSA) in a series of batch experiments with synthetic stormwater of ‘typical’ chemical and microbial composition. The results showed that effective disinfection could be achieved with very low energy consumption; e.g. the current density of 1.74 mA/cm 2 achieved total disinfection in 1.3 min, using only 0.018 kWh per ton of stormwater treatment. Chlorination was found to be the key disinfection mechanism, despite the synthetic stormwater containing only 9 mg/L of chloride. Real stormwater collected from three stormwater treatment systems in Melbourne was then used to validate the findings for indigenous microbe species. Disinfection below the detection limit was achieved for stormwater from the two sites where chloride levels were 9 and 200 mg/l, respectively, but not for the third site where stormwater contained only 2 mg/L chloride. Unfortunately, deterioration of the DSA anode was observed after only 8–10 h of its cumulative operation time, very likely due to high voltage that had to be applied to low saline stormwater to achieve the required current density. In conclusion, ECO was found to be a very promising low energy disinfection technology for stormwater, but far more work is needed to optimise the technology for unique stormwater conditions. [ABSTRACT FROM AUTHOR]