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Biofilters demonstrate promising yet inconsistent removal of faecal pathogens from stormwater. Antimicrobial-producing plants represent safe, inexpensive biofilter design features which can significantly enhance faecal microbe treatment. The microbiota naturally inhabiting biofilters have additionally been established as key mediators of faecal microbe inactivation. To date, however, it remains unknown: (1) to what extent plants, including significant antimicrobial-producing plants, influence the biofilter microbiome; and (2) how this in turn impacts faecal microorganism survival/die-off. The present study employed 16S rRNA sequencing to examine these relationships throughout the soil profiles of differently vegetated biofilters over time. It was found that plants had subtle but significant influences on the composition and structure of resident biofilter bacterial communities, with varying impacts observed throughout biofilter profiles. Bacterial communities inhabiting biofilters comprising significant antimicrobial-producing plants demonstrated distinct compositional and taxonomic differences relative to other configurations. In particular, compared to other biofilters, the best-performing configuration for faecal bacterial treatment, Melaleuca linariifolia (significant antimicrobial-producing plant), exhibited both higher and lower relative frequencies of putative faecal bacterial antagonists (e.g. Actinobacteria) and mutualists (e.g. certain Gammaproteobacteria), respectively. These preliminary findings suggest that antimicrobial plants may enhance populations of microbiota which suppress faecal bacterial survival, and highlight the plant-microbiome relationship as a novel area of focus for optimising biofilter performance.

A large-scale column study was conducted to examine the sediment and nutrient removal performance of stormwater biofilters that contained layers of novel copper-zeolite filter media. The filters were exposed to stormwater under varied dosing frequency over 33 weeks and were assessed for their hydraulic performance and their efficiency in removing sediment and nutrients. The non-vegetated sand filters with layers of copper-zeolite media (SCu filters) achieved consistently good removal of total phosphorus (87%) despite the challenging dry-wet cycles, and the effluent concentration met a long-term irrigation guideline (0.05 mg/L). The same design achieved 51% removal of total nitrogen above the Australian runoff quality load reduction targets (45%). Incorporation of Leptospermum continentale into the copper-zeolite filters (LCCu-T) maintained the phosphorus removal (86%) and led to a slight increase in total nitrogen removal (57%). Both designs maintained good water permeability (200 mm/h at the end of the last wet period). Copper-zeolite played a mixed role in the system: enhancing nutrients removal through precipitation and ion exchange, maintaining high water permeability, limiting the advantages of vegetation on nutrient removal. Future studies should refine biofilter design and vegetation selection to augment the performance of copper-zeolite filters by integrating the advantages of vegetation on nutrient removal. Highlights The first study investigating nutrient removal by copper-zeolite integrated stormwater biofilters.; Consistently higher total phosphorus removal during 33-week operation with intermittent dry periods.; Varied performance in the presence of different vegetation species.; Adequate hydraulic performance of vegetated biofilters.

The synthesis of hydrogen peroxide (H2O2) from H2O and O2 by metal-free photocatalysts (e.g., graphitic carbon nitride, C3N4) is a potentially promising approach to generate H2O2. However, the phot...

Non-vegetated high-flow stormwater filters have had widespread implementation in urban areas for stormwater management due to their small footprints. Relevant studies on investigation and modelling of the clogging of these systems, however, are quite limited, especially where they are based on real field observations. In this study, the infiltration rates (IR) of a field stormwater harvesting system, consisting of individual high-flow modules for water filtration, were monitored over a 2.5-year time period. A simple conceptual model, comprising a rainfall runoff model and a water balance model (that includes a water distribution model and a linear/exponential regression model), was developed to simulate the evolution of the IR of each filter module. The field observations show that the IR of the entire system dropped from 2000 mm h−1 to an average of 711 mm h−1 after 2.5 years of operation, with the filters closer to the inlet having the lowest IR at the end of testing (i.e., only 167 mm h−1). The models were calibrated highly satisfactorily against a different number of field observation events, with an average Nash–Sutcliffe coefficient (E) value of 0.64 and mean absolute error (MAE) value of 11.8. The validation results show that the linear regression model had better performance, with E mostly being positive (0.03–0.60) and MAE values (15.0–18.9) smaller than the exponential regression model (E < 0 in many cases, and MAE = 14.5–20.7). Compared to the results of previous laboratory experiments, data from this study indicate a slower decline rate of IR in field conditions, showing the importance of natural wetting/drying regimes for the longevity of such filters. The model could be very useful for optimisation of the design and long-term maintenance (e.g., replacement of clogged filter modular components) of modular filtration systems.

The face-to-face contact of a vertical heterojunction is beneficial to charge interaction in photocatalysis. However, constructing a vertical heterojunction with uncompromised redox ability still remains a challenge. Herein, we report the successful synthesis of a WO3-TiO2 vertical heterojunction via establishing an internal electric field across the interface. Experimental investigation and computational simulations reveal that strong electric coupling occurs at the WO3-TiO2 interface forming an internal electric field. The internal electric field induces a Z-scheme charge-carrier transfer through the heterojunction under light irradiation, which leads to effective charge separation and maintains high reaction potentials of charge-carriers. The improved photocatalytic activity of the WO3-TiO2 heterojunction is proved by enhanced generation of reactive oxygen species and accelerated Escherichia coli (E. coli) disinfection. This study provides new insights into understanding and designing Z-scheme heterogeneous photocatalysts.

Stormwater drains are common features at city beaches. Stormwater impact from drains is well understood, but the extent and impact of dry-weather flows on water quality and therefore on swimmers is not. Traditional beach monitoring may not be sensitive or frequent enough to assess this risk from drains, and investigation of dry-weather pollution is limited by relatively slow turnaround times for laboratory analysis. This case study describes lessons learned from a trial of citizen science and water quality sensors to monitor drains for dry-weather flows. This involved the use of smartphones and data-collection platforms for community monitoring at signed drains and by trained citizen scientists. Monitoring consisted of photos, observations, and water sampling. A key lesson from the trial was how citizen science can enhance data collected by sensors or by traditional monitoring. Citizen scientists collected data that sensors could not provide on flows, such as size and colour at outlets, and whether flows reached the bay. When combined with sensor data, drains were risk profiled, with higher-risk drains investigated further. Another lesson learned was to adequately resource in-person engagement and communications to motivate and retain citizen scientists. Underestimating resources for engagement translated into less data collected. Community data from signs was a valuable addition, but could have been maximised by simplifying data collection and ensuring signs were close to where observations or photos needed to be taken. The approaches trialled and lessons learned from this project are informative for the design and delivery of similar projects.

The shedding of pathogens by infected humans enables the use of sewage monitoring to conduct wastewater-based epidemiology (WBE). Although most WBE studies use data from large sewage treatment plants, timely data from smaller catchments are needed for targeted public health action. Traditional sampling methods, like autosamplers or grab sampling, are not conducive to quick ad hoc deployments and high-resolution monitoring at these smaller scales. This study develops and validates a cheap and easily deployable passive sampler unit, made from readily available consumables, with relevance to the COVID-19 pandemic but with broader use for WBE. We provide the first evidence that passive samplers can be used to detect SARS-CoV-2 in wastewater from populations with low prevalence of active COVID-19 infections (0.034 to 0.34 per 10,000), demonstrating their ability for early detection of infections at three different scales (lot, suburb, and city). A side by side evaluation of passive samplers (n = 245) and traditionally collected wastewater samples (n = 183) verified that the passive samplers were sensitive at detecting SARS-CoV-2 in wastewater. On all 33 days where we directly compared traditional and passive sampling techniques, at least one passive sampler was positive when the average SARS-CoV-2 concentration in the wastewater equaled or exceeded the quantification limit of 1.8 gene copies per mL (n = 7). Moreover, on 13 occasions where wastewater SARS-CoV-2 concentrations were less than 1.8 gene copies per mL, one or more passive samplers were positive. Finally, there was a statistically significant (p < 0.001) positive relationship between the concentrations of SARS-CoV-2 in wastewater and the levels found on the passive samplers, indicating that with further evaluation, these devices could yield semi-quantitative results in the future. Passive samplers have the potential for wide use in WBE with attractive feasibility attributes of cost, ease of deployment at small-scale locations, and continuous sampling of the wastewater. Further research will focus on the optimization of laboratory methods including elution and extraction and continued parallel deployment and evaluations in a variety of settings to inform optimal use in wastewater surveillance., Wastewater surveillance can track the spread of infectious diseases, and our paper presents a sensitive, simple, and cost-effective method called passive sampling.

Greywater is an alternative water resource, having many favourable characteristics over stormwater or wastewater. In particular, it can be supplied consistently and generated close to desirable end-use applications. Although greywater is considered to contain a low level of contamination, treatment is still required before the end-use, and passive filtration such as biofiltration became a popular option due to its low maintenance and low energy consumption. To this end, a laboratory experiment was conducted with synthetic greywater over 12 months to test the influence of operational characteristics and design factors on pathogen removal from greywater. The role of plants types, saturated zone, and the absence/inclusion of antimicrobial material were tested in a total of 80 biofilter columns. The results showed that the biofilters obtained a median E. coli logarithmic removal of 3.0 across the tested configurations and produced quality of water that meets indoor non-potable use standard (NRMMC, 2006). Further, the infiltration rate and event size were found to significantly influence E. coli removal in greywater biofilters (ANOVA, p

Extreme weather and the proliferation of impervious areas in urban watersheds increases the frequency of flood events and deepens water quality concerns. Bioretention is a type of green infrastructure practice developed to mitigate these impacts by reducing peak flows, runoff volume, and nutrient loads in stormwater. However, studies have shown inconsistency in the ability of bioretention to manage some pollutants, particularly some forms of nitrogen. Innovative sensor and control technologies are being tested to actively manage urban stormwater, primarily in open water stormwater systems such as wet ponds. Through these cyber-physical controls, it may be possible to optimize storage time and/or soil moisture dynamics within bioretention cells to create more favorable conditions for water quality improvements. A column study testing the influence of active control on bioretention system performance was conducted over a 9-week period. Active control columns were regulated based on either maintaining a specific water level or soil moisture content and were compared to free draining (FD) and internal water storage standards. Actively controlled bioretention columns performed similarly, with the soil moisture-based control showing the best performance with over 86% removal of metals and total suspended solids (TSS) while also exhibiting the highest ammonium removal (43%) and second highest nitrate removal (74%). While all column types showed mostly similar TSS and metal removal trends (median 94 and 98%, respectively), traditionally FD and internal water storage configurations promoted aerobic and anaerobic processes, respectively, which suggests that actively controlled systems have greater potential for targeting both processes. The results suggest that active controls can improve upon standard bioretention designs, but further optimization is required to balance the water quality benefits gained by retention time against storage needs for impending storms.

Microbiomes are vast communities of microorganisms and viruses that populate all natural ecosystems. Viruses have been considered to be the most variable component of microbiomes, as supported by virome surveys and examples of high genomic mosaicism. However, recent evidence suggests that the human gut virome is remarkably stable compared with that of other environments. Here, we investigate the origin, evolution and epidemiology of crAssphage, a widespread human gut virus. Through a global collaboration, we obtained DNA sequences of crAssphage from more than one-third of the world's countries and showed that the phylogeography of crAssphage is locally clustered within countries, cities and individuals. We also found fully colinear crAssphage-like genomes in both Old-World and New-World primates, suggesting that the association of crAssphage with primates may be millions of years old. Finally, by exploiting a large cohort of more than 1,000 individuals, we tested whether crAssphage is associated with bacterial taxonomic groups of the gut microbiome, diverse human health parameters and a wide range of dietary factors. We identified strong correlations with different clades of bacteria that are related to Bacteroidetes and weak associations with several diet categories, but no significant association with health or disease. We conclude that crAssphage is a benign cosmopolitan virus that may have coevolved with the human lineage and is an integral part of the normal human gut virome. ispartof: NATURE MICROBIOLOGY vol:4 issue:10 pages:1727-1736 ispartof: location:England status: published

Pollution build-up and wash-off processes are often included in urban stormwater quality models. However, these models are often unreliable and have poor performance at large scales and in complicated catchments. This study tried to improve stormwater quality models by adopting the genetic programming (GP) approach to generate new build-up algorithms for three different pollutants (total suspend solids – TSS, total phosphorus – TP and total nitrogen – TN). This was followed by testing of the new models (also traditional build-up and wash-off models as benchmark) using data collected from different catchments in Australia and the USA. The GP approach informed new sets of build-up algorithms with the inclusion of not just the typical antecedent dry weather period (ADWP), but also other less ‘traditional’ variables - previous rainfall depth for TSS and maximum air temperatures for TP and TN simulation. The traditional models had relatively poor performance (Nash-Sutcliffe coefficient, E < 0.0), except for TP at Gilby Road (GR) (E = 0.21 in calibration and 0.43 in validation). Improved performance was observed using the models with new build-up algorithms informed by GP. Taking TP at GR for example, the best performing model had E of 0.46 in calibration and 0.54 in validation. The best performing models for TSS, TP, and TN are often different, suggesting that specific models shall be used for different pollutants. Insights into further improvements possible for stormwater quality models were given. It is recommended that in addition to the typical build-up and wash-off process, new generations of stormwater quality models should be able to account for the non-conventional pollutant sources (e.g. cross-connections, septic tank leakage, illegal discharges) through stochastic approaches. Emission inventories with information like intensity-frequency-duration (IFD) of pollutant loads from each type of non-conventional source are suggested to be built for stochastic modelling.

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.

Green walls, installed on the side of the buildings, mainly for their aesthetics and micro climate benefits, could become effective on-site greywater treatment solutions. However, far more research is needed to convert these nature-based systems into low-cost water purification technologies. This process study presents the first step in development of greywater-treating green walls by examining how variation in plant spaces and operational conditions (hydraulic loading rate, inflow concentrations and intermittent drying) influence nutrient removal from light greywater. The experiment was conducted over 12 months on a large-scale pilot green wall located in a laboratory in Melbourne, Australia. The results showed that ornamental plant species can successfully adapt to greywater only irrigation regime and play an important role in nitrogen and phosphorus uptake from greywater. Higher performing plants, C. appressa, N. obliterate, M. parvifolium and L. muscari, had on average 7–10% higher TN removal than unvegetated configuration (over 88% removal overall), which is attributed to consistently high NOx uptake. On the other hand, poorer performing plants O. japonicus, P. occidentalis and N. officinale tended to leach NOx, likely due to their shallow or slow developing root systems. While low retention times hindered high TP removal from all tested configurations, high dependency on plant species and operational conditions was still observed, with C. appressa and N. obliterata being the two highest performing plants (34–53% removal during standard operation). The overall phosphorus uptake was found to improve over time, suggesting that plant growth is a significant TP removal mechanism in green walls. While drying caused a performance drop for all designs, higher performing plant species were less affected by changes in operational conditions. The tested configurations showed good resilience to sudden inflow concentration increases, suggesting green walls could be used as a robust and aesthetically attractive on-site greywater treatment system.

The use of a solid polymer electrolyte (SPE) in an anode/SPE/cathode sandwich has emerged as a promising electrochemical configuration to reduce the terminal voltage and thus energy consumption during electrolysis. This study for the first time investigates and compares the efficiency of the electrochemical chlorine production process as well as estimates and compares energy consumption with and without a SPE assembly in the electrolytic cell. Results indicate that at the same current density of 12.5 mA/cm2, Cl2 production rate and instantaneous current efficiency (ICE) were higher when no SPE was used than with a functional SPE, most likely because the SPE occupied one side of the electrode surface, thus limiting the contact of Cl− with its surface to generate Cl2. However, increasing the current density to 31.25 mA/cm2 with a functional SPE resulted in an almost equal Cl2 production rate to that at 12.5 mA/cm2 without a functional SPE, and still the energy consumption per mass of produced Cl2 was the same, although lower ICE was achieved. The study also further investigated the effect of flowrate, and the influence of initial Cl− concentration and the initial pH for the system with the functional SPE.

Complex three-dimensional estuarine hydrodynamic models require large quantities of high-resolution data for model forcing and initialisation. The data are often expensive and difficult to collect with high accuracy (e.g. bathymetry data, riverine flows, water depths, etc.). It may be possible to reduce input data requirements, whilst maintaining predictive capabilities. This is the first study that assesses the sensitivity of a three-dimensional hydrodynamic model of a shallow and narrow urban salt-wedge estuary to input data used for model forcing and initialisation. The model was built using the TUFLOW FV modelling platform and its performance was tested against high-resolution water level, flow velocity, vertical salinity and temperature distribution data. A number of scenarios were used in which data used for model forcing and initialisation, including flow rates, salinity and temperature, wind, bed roughness, bathymetry and vertical mesh discretisation were systematically varied. To assess the sensitivity of model outputs, model predictions were compared to the optimised model predictions for ten periods covering different hydrologic and hydrodynamic conditions. The analysis showed that all model outputs (i.e. water level, velocity, temperature and salinity) were influenced by large and localised water inputs. Due to limited wind fetch of narrow water bodies, wind inputs are expected to have limited impact on hydrodynamic model outputs. However, in this study, flow velocity, salinity and temperature outputs were all influenced by wind inputs. Whilst, accurate bathymetry data are considered essential for developing three-dimensional hydrodynamic models of shallow regions, in this study, uncertainty in the bathymetry data had limited influence on model outputs. Removal of stormwater inputs (i.e. 208 stormwater drains), setting constant salinity for fresh water inputs, weekly averaging of temperature and errors in bathymetry all had minimal impact on model outputs. The results of this case-study can help inform future modelling exercises of narrow and shallow salt-wedge estuaries by focussing efforts on the most important input data. This would potentially lead to substantial reductions in cost and time needed to set up the model.

While biofilters are a stormwater treatment technology there is also the potential to use them for urban agriculture, given that they are vegetated systems. However, it has been found that vegetables irrigated with stormwater can contain concentrations of cadmium (Cd) and lead (Pb) that exceed the guidelines set by the World Health Organization (WHO). The aim of this study was to investigate the effectiveness of various filter media amendments for reducing the uptake of Cd and Pb into the edible portions of vegetables. Three types of amendments – zeolite, hydroxyapatite and lime – and three different vegetable types – broad bean (Vicia faba), kale (Brassica oleracea Acephala Group) and radish (Raphanus sativus) – were tested in laboratory-scale biofilter columns. This study found that metal concentrations in the edible portions of plants were below the WHO and Food Standards for Australia and New Zealand guideline values except for Pb in radish. The effectiveness of the amendments was dependent on the metal. Hydroxyapatite was found to be most effective for restricting plant uptake of Pb while Cd uptake was most effectively restricted by lime. Vegetable type was also found to influence plant metal uptake. Radishes were found to have the highest Pb and Cd concentration in the edible portion compared to kale or broad bean pods. This is most likely due to the edible part of radishes (i.e. the root) being in direct contact with the upper portion of the filter media, where metals predominantly accumulate, and suggests that root vegetables may not be suitable for cultivation in stormwater biofilters.

Although electrochemical oxidation (ECO) has shown excellent potential for disinfecting wastewater and surface waters, its application on urban stormwater has been rarely tested. In order to improve stormwater ECO design, this paper explores the major inactivation processes using Boron Doped Diamond (BDD) and titanium Dimensional Stable Anodes (DSA). Both BDD and DSA showed comparable disinfection rates. The mechanism study suggested that BDD relied on hydroxyl radical and the presence of chloride ions, while DSA disinfected stormwater mainly via the production of free‑chlorine. A deterioration study carried out at a catchment in Melbourne, showed a steady performance for BDD and revealed that DSA's performance degraded with time, likely linked to the high operational voltage required for specific chemistry of stormwater. Scanning Electron Microscopes and an Energy Dispersive X-ray Detector tests confirmed elemental losses occurred on the DSA surface, together with an aluminium/silicon coating layer potentially sourced from the stormwater clayish sediments. Furthermore, disinfection by-products in electrochemical disinfected stormwater using either BDD or DSA were at least one order of magnitude lower than the Australia Drinking Water Guidelines limits. The mechanism and long-term study demonstrated that careful anode selection is required as some anodes will deteriorate in stormwater matrices faster than others.

Aquatic recreation in urban estuaries worldwide is often restricted by fecal pollution. Variability in the occurrence of fecal pathogens and their differential virulence potentials within these estuaries may result in variable public health risks. To address this hypothesis, Campylobacter were isolated from the Yarra River estuary, Australia and then characterized via HeLa cell cytotoxicity and attachment to and the invasion of Caco-2 monolayers. Overall, 54% (n=216) of estuarine samples (water and sediment combined) yielded biochemically confirmed culturable Campylobacter; higher detection was recorded in water (92%, n=90) than in the bank and bed sediments combined (27%, n=126). The seasonality of occurrence was not significant. HeLa cell cytotoxicity revealed that estuarine Campylobacter had low cytotoxin titers; the 95% confidence interval (CI) ranged between 61 and 85, which was markedly lower than the mean value (~386) for the C. jejuni 11168 reference pathogenic strain. The Caco-2 attachment of estuarine Campylobacter isolates (n=189) revealed that the 95%CI for the attachment efficiency of the test strains ranged between 0.09 and 0.1%, with only 3.7% having a higher efficiency than the 5th percentile value for C. jejuni 11168. None of the estuarine strains exhibited Caco-2 invasion capabilities. In contrast to the common assumption during quantitative microbial/risk assessments (QMRAs) that all environmental strains are pathogenic, the present results revealed that Campylobacter within the Yarra River estuary had very low virulence potential. Since this is the first study to use human epithelial cell lines to characterize estuary-borne pathogens, these results generate valuable insights for a better understanding of the public health risks in urban estuaries that will underpin more robust QMRAs.

Preliminary laboratory work has shown that electrochemical oxidation (ECO) is a promising technology for disinfection of harvested stormwater. This paper focuses on understanding how stormwater chemistry (e.g. pH, chloride, bicarbonate, ammonia and total organic carbon - that can vary substantially between sites) impacts the disinfection performance of ECO. Real stormwater samples from four different urban catchments were collected and tested for ECO performance in disinfecting stormwater pathogens using a boron doped diamond anode under the current density of 4.2 mA/cm2. Results showed that total disinfection of indigenous Escherichia coli (E. coli), as well as three different stormwater pathogens (Enterococci, Campylobacter and C. perfringens) was achievable for all four tested stormwater within 30 min. Compared to the synthetic stormwater, lower disinfection rates were observed in real stormwater which has more complex chemistry. Stormwater chloride concentration was the only tested parameter that had significant impact on the treatment performance, with higher initial stormwater chloride concentration leading to an increased disinfection rate. Disinfection by-products in the treated stormwater were well below the Australian Drinking Water Guideline value for health, with its production level positively correlated to the pH values of stormwater.

Water sampling is an essential undertaking for water utilities and agencies to protect and enhance our natural resources. The high variability in water quality, however, often necessitates a spatially distributed sampling program which is impeded by high-cost and large sampling devices. This paper presents the BoSL FAL Pump - a low-cost, easily constructed, 3D-printed peristaltic pump which can be made from commonly available components and is sized to suit even the most space constrained installations. The pump is 38 mm in height and 28 mm in diameter, its components cost $19 AUD and the construction time is just 12 min (excluding 3D printing times). The pump is driven by a direct current motor which is commonly available, cheap and allows for flexibility in the energy supply (5–12 V). Optionally, the pump has a Hall effect sensor and magnet to detect rotation rates and pumping volumes to improve the accuracy of pumping rates/volumes. The pump can be easily controlled by commonly available microcontrollers, as demonstrated by this paper which implements the ATmega328P on the Arduino Uno R3. This paper validates the pump for long-term deployments at flow rates of up to 13 mL per minute in 0.14 mL volume increments at accuracy levels of greater than 99%. The pump itself is scalable, allowing for a wider range of pumping rates when, for example, large volume samples are required for pathogen and micropollutant detection.

Campylobacter spp. can survive and be transmitted from a range of environments. Here, we examine eight draft genome sequences of Campylobacter volucris, identified as part of an examination of waterborne Campylobacter species. This is the first report of environmental survival of C. volucris outside gull species.

Data collection in urban drainage systems comes with many challenges. However, many examples already exist, containing numerous useful lessons learned. This chapter therefore contains several urban drainage and stormwater management metrology case studies, selected to cover a wide range of scopes, scales, objectives, climates, data validation methods, and data storage approaches. The case studies are initiated by academics as well as by institutions from the water industry.

In search of practical and affordable tools for wastewater-based surveillance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), three independent field experiments were conducted using three passive sampler sorbents (electronegative membrane, cotton bud, and gauze) in Guelph, Ontario, Canada. Total daily cases during this study ranged from 2 to 17/100,000 people and 43/54 traditionally collected wastewater samples were positive for SARS-CoV-2 with mean detectable concentrations ranging from 8.4 to 1780 copies/ml. Viral levels on the passive samplers were assessed after 4, 8, 24, 48, 72, and 96 hrs of deployment in the wastewater and 43/54 membrane, 42/54 gauze, and 27/54 cotton bud samples were positive. A linear accumulation rate of SARS-CoV-2 on the membranes was observed up to 48 hours, suggesting the passive sampler could adequately reflect wastewater levels for up to two days of deployment. Due the variability in accumulation observed for the cotton buds and gauzes, and the pre-processing steps required for the gauzes, we recommend membrane filters as a simple cost-effective option for wastewater-based surveillance of SARS-CoV-2., This research provides evidence to support the use of electronegative membranes as passive samplers for monitoring of SARS-CoV-2 in wastewater.

BackgroundMultiple bacteria, viruses, protists, and helminths cause enteric infections that greatly impact human health and wellbeing. These enteropathogens are transmitted via several pathways through human, animal, and environmental reservoirs. Individual quantitative PCR (qPCR) assays have been extensively used to detect enteropathogens within these types of samples, whereas the TaqMan Array Card (TAC) that allows simultaneous detection of multiple enteropathogens has only previously been validated in human clinical samples.MethodsHere, we performed a comprehensive double-blinded comparison of the performance of a custom TAC relative to standard qPCR for the detection of eight enteric targets, by using spiked samples, wastewater from Melbourne (Australia), and human, animal, and environmental samples from informal settlements in Suva, Fiji.FindingsBoth methods exhibited high and comparable specificity (TAC: 100%, qPCR: 94%), sensitivity (TAC: 92%; qPCR: 100%), and quantitation accuracy (TAC: 91%; qPCR: 99%) in non-inhibited sample matrices. PCR inhibitors substantially impacted detection via TAC, though this issue was alleviated by 10-fold sample dilution. Among samples from informal settlements, the two techniques were comparable for detection (89% agreement) and quantitation (R2= 0.82). The TAC additionally included 38 other targets, enabling detection of diverse faecal pathogens and extensive environmental contamination that would be prohibitively labour intensive to assay by standard qPCR.InterpretationOverall, the two techniques produce comparable results across diverse sample types, with qPCR prioritising greater sensitivity and quantitation accuracy, and TAC trading small reductions in these for a cost-effective larger enteropathogen panel that enables a greater number of enteric pathogens to be analysed concurrently, which is beneficial given the abundance and variety of enteric pathogens in environments such as urban informal settlements. The ability to monitor multiple enteric pathogens across diverse reservoirs in turn allows better resolution of pathogen exposure pathways, and the design and monitoring of interventions to reduce pathogen load.FundingWellcome TrustOur Planet, Our Healthprogram [OPOH grant 205222/Z/16/Z].

Summary Background Multiple bacteria, viruses, protists, and helminths cause enteric infections that greatly impact human health and wellbeing. These enteropathogens are transmited via several pathways through human, animal, and environmental reservoirs. Individual qPCR assays have been extensively used to detect enteropathogens within these types of samples, whereas the TaqMan array card (TAC), which allows simultaneous detection of multiple enteropathogens, has only previously been validated in human clinical samples. Methods In this methodological comparison study, we compared the performance of a custom 48-singleplex TAC relative to standard qPCR. We established the sensitivity and specificity of each method for the detection of eight enteric targets, by using spiked samples with varying levels of PCR inhibition. We then tested the prevalence and abundance of pathogens in wastewater from Melbourne (Australia), and human, animal, and environmental samples from informal settlements in Suva, Fiji using both TAC and qPCR. Findings Both methods exhibited similarly high specificity (TAC 100%, qPCR 94%), sensitivity (TAC 92%, qPCR 100%), and quantitation accuracy (TAC 91%, qPCR 99%) in non-inhibited sample matrices with spiked gene fragments. PCR inhibitors substantially affected detection via TAC, though this issue was alleviated by ten-fold sample dilution. Among samples from informal settlements, the two techniques performed similarly for detection (89% agreement) and quantitation (R2 0·82) for the eight enteropathogen targets. The TAC additionally included 38 other enteric targets, enabling detection of diverse faecal pathogens and extensive environmental contamination that would be prohibitively labour intensive to assay by standard qPCR. Interpretation The two techniques produced similar results across diverse sample types, with qPCR prioritising greater sensitivity and quantitation accuracy, and TAC trading small reductions in these for a cost-effective larger enteropathogen panel enabling a greater number of enteric pathogens to be analysed concurrently, which is beneficial given the abundance and variety of enteric pathogens in environments such as urban informal settlements. The ability to monitor multiple enteric pathogens across diverse reservoirs could allow better resolution of pathogen exposure pathways, and the design and monitoring of interventions to reduce pathogen load. Funding Wellcome Trust Our Planet, Our Health programme.

Biofiltration systems can help mitigate the impact of urban runoff as they can treat, retain and attenuate stormwater. It is important to select the optimal design characteristics of biofilters (e.g., vegetation, filter media depth) to ensure high treatment performance. Operational conditions (e.g., infiltration rate) can also lead to significant changes in biofilter treatment performance over time. The impact of specific operational conditions on water quality treatment performance of stormwater biofilters is still not well understood. Furthermore, despite the importance of design characteristics and operational conditions on biofilter treatment performance, there is a lack of models that can be used to determine the optimal design and operation. In this paper, we developed a series of statistical models to predict the Total Phosphorus (TP) and Total Nitrogen (TN) removal performance of stormwater biofilters using various numbers of design characteristics and operational conditions. These statistical models were tested using data collected from four extensive laboratory-scale biofilter column studies. It was found that all models performed relatively well with a Nash-Sutcliffe Efficiency (NSE) of 0.42 - 0.61 for TP and 0.37 - 0.63 for TN. The most important design characteristics were filter media type and depth for TP treatment, and vegetation type and submerged zone depth for TN treatment. In addition, infiltration rate and inflow concentrations were the operational conditions that greatly influence outflow TP and TN concentrations from stormwater biofilters. As such, these variables need to be carefully considered when designing and operating stormwater biofilters. Sensitivity analysis results indicate that the model was quite sensitive to all regression coefficients and intercepts. Additional modelling exercises show that the model could be further simplified by reducing the number of cross-correlated parameters. These models can be used by practitioners for not just optimising the design, but also operating biofilters using real-time monitoring and control to achieve optimum performance.

Low energy and cost solutions are needed to combat raising water needs in urbanised areas and produce high quality recycled water. In this study, we investigated key processes that drive a unique greywater treatment train consisting of a passive green wall biofiltration system followed by disinfection using a Boron-doped diamond (BDD) electrode with a solid polymer electrolyte (SPE). In both systems, the treatment was performed without any additional chemicals and pollutants of concern were monitored for process evaluation. The green wall system removed over 90% of turbidity, apparent colour, chemical oxygen demand, total organic carbon, and biological oxygen demand, and 1 log of E. coli and total coliforms, mostly through biological processes. The green wall effluent met several proposed greywater reuse guidelines, except for E. coli and total coliform treatment (below 10 MPN/100 mL). Further disinfection of treated greywater (contained 28 mg/L Cl¯ and electrical conductivity (EC) of 181.3 µS/cm) by electrolysis at current density 25 mA/cm2 inactivated over 3.5 logs of both E. coli and total coliforms, in 10 – 15 min of electrolysis, resulting in recycled water with less than 2 MPN/100 mL. A synergistic effect between electrochemically-generated free chlorines and reactive oxygen species contributed to the inactivation process. Although the treated water contained diluted chloride and had low EC, estimated energy consumption was just 0.63 – 0.83 kWh/m3. This is the first study to show the effectiveness of a low energy and a low cost greywater treatment train that combines green urban infrastructure with BDD electrochemical treatment process with SPE, offering a reliable and an environmentally-friendly method for greywater reuse.

The treatment of toxic Microcystis aeruginosa ( M. aeruginosa) by electrolysis using a boron-doped diamond (BDD) anode with a solid polymer electrolyte (SPE) was investigated. In order to examine the role of oxidizing agents, the electrolysis of M. aeruginosa was conducted in distilled deionised water (DIW) with and without sodium chloride aqueous electrolyte. Furthermore, to verify the system’s ability for freshwater treatment without the addition of chemicals, we also tested filtered local reservoir water. M. aeruginosa cell inactivation and microcystins degradation occurred in the DIW system without a supporting aqueous electrolyte, but cell inactivation occurred at slightly slower rate compared to when 30 mg/L Cl − was added. Even though these rates were even slower in the pre-filtered reservoir water, around 90% inactivation and toxin degradation was still observed after 30 min, and cells were not able to re-grow when subsequently exposed to optimum growth conditions. These results for the first time demonstrate the ability of the SPE system to efficiently treat contaminated freshwaters, even without the addition of chemicals or adjustment of electrical conductivity. Importantly, significant changes in cell morphology after electrolysis in different water matrices were observed. In the DIW with 30 mg/L Cl − test based on the significant differences in oxidants concentrations in the presence and absence of M. aeruginosa suggest that there was a synergistic effect of in situ electro-generated ozone and chlorine species in cell inactivation, however, hydrogen peroxide did not seem to assist in the treatment performance. This study suggests that the electrochemical treatment of BDD with SPE, with and without supporting electrolyte is an effective method for the removal of both toxic cyanobacteria and cyanotoxins.

The microbial community and function along with nitrate/nitrite (NOx) removal rates, and nitrogen (N) partitioning into "uptake", "denitrification", and "remaining" via isotope tracers, were studied in soil bioretention mesocolumns (8 unique plant species). Total denitrification gene reads per million (rpm) were positively correlated with % denitrified ( r = 0.69) but negatively correlated with total NOx removal following simulated rain events ( r = -0.79). This is likely due to plant-microbe interactions. Plant species with greater root volume, plant and microbial assimilation %, and NOx removal % had lower denitrification genes and rates. This implies that although microorganisms have access to N, advantageous functions, like denitrification, may not increase. At the conclusion of the 1.5-year experiment, the microbial community was strongly influenced by plant species within the Top zone dominated by plant roots, and the presence or absence of a saturated zone influenced the microbial community within the Bottom zone. Leptospermum continentale was an outlier from the other plants and had much lower denitrification gene rpm (average 228) compared to the other species (range: 277 to 413). The antimicrobial properties and large root volume of Leptospermum continentale likely caused this denitrification gene depression.

A spatial model is presented, based on urban planning concepts for abstracting urban form characteristics in new and existing areas. Requiring input maps of land use, elevation, population and parameters from planning regulations, the model conceptualises (on a spatial grid) attributes including impervious fraction, allotment geometry and roof areas among other relevant characteristics for integrated urban water management. The model is calibrated to three different Melbourne districts, varying in size (10–60 km2) and land use. Performance was evaluated by comparing modelled outputs with observations of total dwelling count, employment and spatial distribution of impervious fraction and residential roof areas. Results not only highlight reasonably good prediction, particularly with spatially variable indicators such as imperviousness across all case studies, but also logical contrasts and consistency in the chosen planning parameters across the different case study districts. Discrepancies highlight aspects needing improvement and potential for exploring auto-calibration and model sensitivity.

Bed sediment resuspension is a potential source of faecal microorganisms in the water column of estuaries. As such, it is important to identify the survival of faecal microorganisms in these bed sediments and understand how bed sediment resuspension impacts the quality of estuarine waters. This study explores the effect of bed sediment resuspension on Escherichia coli concentrations in the water column and the persistence of E. coli in the water column and bed sediments of the Yarra River estuary in South-Eastern Australia. Using sediment cores, we identified that the resuspension of both surficial sediments (e.g., by tidal movements) and deeper bed sediments (e.g., by large storm events) can increase E. coli concentrations in the water column by up to 20 times in estuaries in oceanic climates. Bed sediment resuspension can result in increased E. coli concentrations in the water column even up to 24 days after E. coli first enters the estuarine water. This study demonstrates that faecal microorganisms, such as E. coli, can persist for extended periods in estuarine bed sediments, which may then be re-entrained into the water column via recreational activities, high flow events, or tidal fluctuations. If the survival and resuspension processes observed here hold true for pathogenic microorganisms, the resuspension of bed sediments may indeed represent an increased public health risk.

Sediment cores from aquatic environments can provide valuable information about historical pollution levels and sources. However, there is little understanding of the uncertainties associated with these findings. The aim of this study is to fill this knowledge gap by proposing a framework for quantifying the uncertainties in historical heavy metal pollution records reconstructed from sediment cores. This uncertainty framework consists of six sources of uncertainty: uncertainties in (1) metals analysis methods, (2) spatial variability of sediment core heavy metal profiles, (3) sub-sampling intervals, (4) the sediment chronology, (5) the assumption that metal levels in bed sediments reflect the magnitude of metal inputs into the aquatic system, and (6) post-depositional transformation of metals. We apply this uncertainty framework to an urban floodplain lake in South-East Australia (Willsmere Billabong). We find that for this site, uncertainties in historical dated heavy metal profiles can be up to 176%, largely due to uncertainties in the sediment chronology, and in the assumption that the settled heavy metal mass is equivalent to the heavy metal mass entering the aquatic system. As such, we recommend that future studies reconstructing historical pollution records using sediment cores from aquatic systems undertake an investigation of the uncertainties in the reconstructed pollution record, using the uncertainty framework provided in this study. We envisage that quantifying and understanding the uncertainties associated with the reconstructed pollution records will facilitate the practical application of sediment core heavy metal profiles in environmental management projects.

Green walls are increasingly being considered as a suitable greywater treatment technology. Nevertheless, until now there have been no clear recommendations for the use of effective lightweight media in greywater treating green walls. Previous studies of potentially suitable growing media have suggested that a combination of perlite and coco coir might be the most effective for these novel systems. However, there is no clear understanding of what proportion of perlite and coir should be used and how different mixes would affect greywater treatment. This work tested the hydraulic and pollutant removal performance of six different perlite and coco coir media mixes in an unvegetated column experiment. The results suggested that there is a point between 2:1 and 3:1 ratios of perlite to coir where the infiltration rate significantly increases, as the result of perlite dominance. As the infiltration rate increases, the mix gets less prone to clogging, but this negatively affects pollutant removal performance, with insufficient time for biological processes. We therefore optimised the mix for effective long-term treatment of total suspended solids, total nitrogen, chemical oxygen demand and Escherichia coli. Unfortunately, total phosphorus removal from greywater was limited for all tested mixes. This study also showed that attention should be given to greywater inflow dynamics and expected daily water treatment capacity; e.g. systems with a lower hydraulic loading were able to use greater proportion of coir in the mix achieving greater water treatment performance, while systems with higher hydraulic loadings require faster flowing mixes with lower coir proportion.

Stormwater constructed wetlands are not well characterised for their ability to remove pathogens which can pose public health risks during stormwater harvesting activities. This study investigated the behaviour of faecal indicator organism Escherichia coli (E. coli) and reference pathogen Campylobacter spp. in stormwater constructed wetlands, using a case study system located in Melbourne, Australia. Grab sampling and event-based monitoring revealed influent concentrations of E. coli were typical of other urban stormwater studies, yet Campylobacter concentrations were orders of magnitude above those urban stormwater studies used to develop the Australian Guidelines for Water Recycling, reached levels typical of raw domestic wastewater. The wetland consistently removed E. coli from stormwater (mean log removal 0.96, range 0.19–1.79), while Campylobacter spp. concentrations were often higher in outflow than inflow (mean log removal 0.05, range −0.9-1.25). These results indicate that E. coli is a poor indicator for this reference pathogen. The log reductions of both organisms also failed to meet the criteria specified for any end-use, as listed in the Australian Guidelines for Water Recycling, suggesting further treatment is required prior to harvesting. Finally, this study proposed that direct faecal deposition by waterfowl faeces was a microbial source to stormwater wetlands and that this was partly responsible for the varied microbial removal rates observed. Overall, this work validates the need for further characterisation of pathogens in raw urban stormwater, and the ability for water sensitive urban design features, such as wetlands, to remove both indicator and pathogenic microorganisms.

Urban green infrastructure (GI) such as biofiltration systems (also known as bioretention, biofilters, rain gardens) are being increasingly implemented in different parts of the world to enhance urban greening whilst controlling stormwater pollution. Treatment effectiveness has been shown to be reliant upon the surrounding climate, including rainfall patterns (e.g. length of wet and dry weather) and temperature. Plant species play a key role in treatment, yet, the response of different plant species to pollutant removal under different climatic and environmental conditions is still not fully known. This information is pertinent to ensure sustained biofilter performance under a range of conditions. This study investigates the change in biofilter nutrient and E. coli removal performance in the presence of four plant species (Canna indica, Carex appressa, Ginkgo biloba and Miscanthus sinensis) with distinct above and below ground characteristics, when exposed to wet weather, dry weather and cold weather conditions. The extent of the decline in nutrient treatment performance following extended drying and under cold conditions was found to be species-specific. Miscanthus sinensis was the best performer and was also found to be cold-resistant. With the exception of Miscanthus sinensis, all plant species were more impacted by the cold temperature (decrease from 70% to 45% TN removal on average

Accurate estimation of faecal microorganism levels in water systems, such as stormwater drains, creeks and rivers, is needed for appropriate assessment of impacts on receiving water bodies and the risks to human health. The underlying hypothesis for this work is that a single conceptual model (the MicroOrganism Prediction in Urban Stormwater model – i.e. MOPUS) can adequately simulate microbial dynamics over a variety of water systems and wide range of scales; something which has not been previously tested. Additionally, the application of radar precipitation data for improvement of the model performance at these scales via more accurate areal averaged rainfall intensities was tested. Six comprehensive Escherichia coli (E. coli) datasets collected from five catchments in south-eastern Australia and one catchment in Raleigh, USA, were used to calibrate the model. The MOPUS rainfall-runoff model performed well at all scales (Nash-Sutcliffe E for instantaneous flow rates between 0.70 and 0.93). Sensitivity analysis showed that wet weather urban stormwater flows can be modelled with only three of the five rainfall runoff model parameters: routing coefficient (K), effective imperviousness (IMP) and time of concentration (TOC). The model’s performance for representing instantaneous E. coli fluctuations ranged from 0.17 to 0.45 in catchments drained via pipe or open creek, and was the highest for a large riverine catchment (0.64); performing similarly, if not better, than other microbial models in literature. The model could also capture the variability in event mean concentrations (E = 0.17–0.57) and event loads (E = 0.32–0.97) at all scales. Application of weather radar-derived rainfall inputs caused lower overall performance compared to using gauged rainfall inputs in representing both flow and E. coli levels in urban drain catchments, with the performance improving with increasing catchment size and being comparable to the models that use gauged rainfall inputs at the large riverine catchment. These results demonstrate the potential of the MOPUS model and its ability to be applied to a wide range of catchment scales, including large riverine systems.

Coupling TiO2 with WO3 to develop photocatalytic heterojunctions is one of the most widely used strategies to realize their superior photoactivity. However, the interfacial charge transfer in these heterojunctions is not efficient to achieve an optimized activity. For the first time, the present study reports a facile hydrolysis-hydrothermal approach, whereby ultradispersed TiO2 nanocrystals and WO3 nanorods are concurrently anchored onto reduced graphene oxide (rGO) and formed a novel Z-scheme heterojunction photocatalyst TiO2/rGO/WO3 (TRW). Transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence spectra (PL) are employed to characterize TRW. Control experiments indicate that, in the synthesis process, glucose and the by-product sodium chloride from the hydrolysis reactions are critical for forming highly dispersed and uniform-sized TiO2 nanocrystals and WO3 nanorods. Compared with TiO2/WO3 nanocomposites, TRW shows enhanced activity for bacterial inactivation under simulated solar light. As confirmed by electrochemical characterizations and the reactive oxygen species, rGO in TRW suppresses the recombination of electron-hole pairs and boosts the O2 reduction reactions during photocatalytic process. Z-scheme electron transfer in TRW is proposed based on surface redox reactions and XPS analysis after light irradiation. This study could provide a new clue for designing graphene-based heterojunction photocatalysts for environmental applications.

Background: The intense interactions between people, animals and environmental systems in urban informal settlements compromise human and environmental health. Inadequate water and sanitation services, compounded by exposure to flooding and climate change risks, expose inhabitants to environmental contamination causing poor health and wellbeing and degrading ecosystems. However, the exact nature and full scope of risks and exposure pathways between human health and the environment in informal settlements are uncertain. Existing models are limited to microbiological linkages related to faecal-oral exposures at the individual level, and do not account for a broader range of human-environmental variables and interactions that affect population health and wellbeing. Methods: We undertook a 12-month health and environmental assessment in 12 flood-prone informal settlements in Makassar, Indonesia. We obtained caregiver-reported health data, anthropometric measurements, stool and blood samples from children

In low prevalence settings the development of sensitive and specific quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR) tests to detect SARS-CoV-2 (the virus causing COVID-19) in sewage presents the possibility of using sewage sampling as a diagnostic test for the presence of infected people in the catchment of the sampled sewer. However, the usefulness of such surveillance has not been quantified. In this study in the Australian state of Victoria between August and October 2020 the location of each known SARS-CoV-2-infected person was determined on each day from two days before onset to 55 days after, in 46 metropolitan and rural sewer catchments sampled weekly – a total of 71 positive and 275 negative samples, and 354,155 person-days of location data. These were categorised by time since onset and distance from the sampling site. The odds of detection in sewage were between 5 and 20 times higher where known cases were present, with less effect of distance than time since onset. Using positive qRT-PCR in a sewage sample as a diagnostic test not just for viral RNA in the sample, but for the presence of known infected people in the catchment on the same day, the sensitivity was moderate (31% to 76%) and the specificity high (87% to 94%). The odds of detection were increased with increased numbers of known infected people but decreased with increased distance and time since onset. The probability of detection of the viral subgenome in sewage samples was about 10% when one known infected person was present, and this increased with higher numbers of known infected people and greater proximity to the sampling site. Sewage surveillance can be used to detect people infected with SARS-CoV-2 in the catchment, directing a search for infectious clinical cases and other public health actions. However, detection at least eight weeks after onset may be due to existing cases rather than new ones, and, although not zero, the probability of detecting a single case is low., Graphical abstract Unlabelled Image

There is growing interest in using alternative water sources such as rainwater harvesting and treatment systems to supplement traditional sources and secure a stable supply. For such systems, it is important to ensure adequate water quality, as microbial contamination can be a risk factor in rainwater. The primary objective of this study was to provide proof-of-concept for the microbial treatment capacity of a residential scale rain-to-hot-water treatment system to be installed in Melbourne, Australia. The system consists of a filtration, UV and heat-pump hot water unit, and disinfects roofwater prior to use of the hot water for bath, shower and laundry. The system's efficiency was evaluated using long-term challenge tests investigating the full system and each of the separate components. The microbial treatment performance was assessed based on the systems' ability to treat high levels of E. coli, E. faecalis, Campylobacter, Salmonella and MS2 phage under challenging conditions; with varying flow rates (10-40 L/min) and microbe concentrations (104-105unit/L), and in scenarios of a power outage. Over a compressed year of operation, the full rain-to-hot-water treatment system was extremely efficient at reducing concentrations of E. coli, E. faecalis, Campylobacter, Salmonella and FRNA phages, with log reductions ranging from the lowest average of 2.1log reductions for Salmonella to a maximum of >5.1log for E. coli. Most of the treatment was provided by the UV system, and any remaining microbes present after this point were deactivated by the heat-pump system (provided that the water was given enough time to warm up). Additional modelling work showed that UV intensity, UV transmissivity and contact time (for the UV system) and temperature (for the heat-pump hot water system) could be used as parameters to predict microbial treatment performance of the system, indicating that these easily-measurable parameters could assist with ongoing operation optimisation and maintenance of such systems.

Campylobacter is a pathogen frequently detected in urban stormwater worldwide. It is one of the leading causes of enteric disease in many developed countries and is the leading cause of enteric disease in Australia. Prior to harvesting stormwater, adequate treatment is necessary to mitigate risks derived from such harmful pathogens. The goal of this research was to estimate the health risks associated with the exposure to Campylobacter when harvesting urban stormwater for toilet flushing and irrigation activities, and the role treatment options play in limiting risks. Campylobacter data collected from several urban stormwater systems in Victoria, Australia, were the inputs of a Quantitative Microbial Risk Assessment model. The model included seven treatment scenarios, spanning wetlands, biofilters, and more traditional treatment trains including those recommended by the Australian Guidelines for Water Recycling. According to our modeling and acceptable risk thresholds, only two treatment scenarios could supply water of sufficient quality for toilet flushing and irrigation end-uses: (1) using stormwater biofilters coupled with UV-treatment and (2) a more conventional coagulation, filtration, UV, and chlorination treatment plant. Importantly, our modeling results suggest that current guidelines in place for stormwater reuse are not adequate for protecting against exposure to Campylobacter. However, more research is required to better define whether the Campylobacter detectable in stormwater are pathogenic to humans.

Sustainable stormwater treatment systems remove pollutants using low energy, low maintenance and low cost solutions. Inactivation due to biotic stressors is one of the processes that govern the removal of faecal microorganisms in these systems. One such stress is the possible production of antimicrobial compounds by plants growing in sustainable stormwater treatment systems, potentially enhancing the removal of faecal pathogens. To this end, this study has investigated the antimicrobial potential of 17 Australian native plant species that are suitable for application in these systems but have not been tested for their antimicrobial activity within their seed exudates, seed extracts and/or seedling extracts. The extracts and exudates were tested using the agar well diffusion method. Nine of the selected plant species inhibited the growth of Escherichia coli. Among of the antibacterial plants, Melaleuca ericifolia, which has been previously applied in stormwater treatment systems, can be a suitable candidate for further study as it demonstrated antibacterial activity within all tested components. This species should be utilised in stormwater treatment facilities due to its effective nitrogen uptake, maintenance of hydraulic conductivity, and due to its potential effectiveness at inactivating microbial pathogens.

The public health risks associated with pathogens in urban stormwater have been well established, making it necessary to ensure adequate treatment of the stormwater before it is discharged into recreational water bodies or is harvested for reuse. Biofilters, also known as stormwater bioretention systems or raingardens, have shown promising, yet variable, results in reducing indicator bacteria in stormwater. Different biofilter design elements, such as filter media composition and vegetation type, have been found to cause this variable removal performance. Although plants play a key role in the treatment of pollutants, relatively little work has been conducted to understand the importance of interactions between vegetation and the biofilter microbial community on fecal microbial removal. A laboratory-scale biofilter experiment was conducted using Escherichia coli as the test fecal microorganism. Biofilter columns with differing soil media and vegetation types were dosed over a two month span, during which inflow and outflow samples were collected to evaluate system performance. The columns were then decommissioned to collect rhizosphere and bulk soil samples. Root exudates were extracted and used in an E. coli survival study to evaluate their contribution to system performance. The study demonstrated that the antagonistic effects of root exudates/rhizosphere microbes and Cu2+ exchanged zeolite antimicrobial filter media adversely impact the survival of E. coli retained within stormwater biofilters. Furthermore, leaf and flower/seed extracts of L. continentale showed some potential antibacterial activity against E. coli. This work supports the concept that natural processes in biological systems can deliver effective results in the removal of fecal microorganisms, and should be promoted to the extent possible in stormwater green infrastructure.

Graphene is widely used as a catalyst support for improved charge separation in TiO2 photocatalysis. However, the surface oxygen reduction activity of TiO2/graphene might be hindered due to the electron storage ability of graphene. In this study, highly dispersed TiO2 and carbon dots (C-dots) co-decorated reduced graphene oxide (CTR) is synthesized via a simple hydrothermal reaction using TiCl4 and glucose. Transmission electron microscope, X-ray diffraction, Raman spectroscopy, thermogravimetric analysis and Fourier transform IR spectroscopy are employed to characterize the CTR nanocomposite. The comparison experiment confirmed that C-dots were sourced from the carbonization of glucose. Glucose and TiCl4 which are mutual dispersants, are critical for forming highly dispersed and uniform-sized C-dots and TiO2 nanocrystals. With well dispersed TiO2 and C-dots at separated sites of reduced graphene oxide surface, CTR shows enhanced photocatalytic bacterial inactivation performance under simulated solar light. As confirmed by the reactive oxygen species production, the generation of superoxide anion (O2−) and hydrogen peroxide (H2O2) is improved. The electrochemical characterization reveals that charge separation in CTR photocatalysis is also promoted. Taken together, the concurrently improved charge separation and surface oxygen reduction activity contribute to an accelerated photocatalytic bacteria inactivation process.

Current Water Sensitive Urban Design (WSUD) models are either purely technical or overly simplified, lacking consideration of urban planning and stakeholder preferences to adequately support stakeholders. We developed the Urban Biophysical Environments and Technologies Simulator (UrbanBEATS), which integrates stormwater management with urban planning to support the design and implementation of WSUD. This study specifically describes and tests UrbanBEATS' WSUD Planning Module, which combines spatial analysis, infrastructure design, preference elicitation and Monte Carlo methods to generate feasible stormwater management and harvesting infrastructure options in greenfield and existing urban environments. By applying UrbanBEATS to a real-world greenfield development case study in Melbourne, Australia (with data sourced from the project's water management plans and design consultants), we explore the variety of options generated by the model and analyse them collectively to demonstrate that UrbanBEATS can design similar WSUD systems (e.g. select suitable technology types, their sizes and locations) to actual infrastructure choices.

Green walls that effectively treat greywater have the potential to become a part of the solution for the issues of water scarcity and pollution control in our cities. To develop reliable and efficient designs of such systems, the following two research questions were addressed: what would be the optimal design of a green wall for greywater treatment, and how tall should the system be to assure adequate treatment. This paper reports on (i) a long-term pollutant removal comparison study of two typical green wall configurations: pot and block designs, and (ii) a short-term profile study exploring pollutant retention at different heights of a three-level green wall, across different plant species. Removal of suspended solids (TSS), nitrogen (TN), phosphorus (TP), chemical oxygen demand (COD) and Escherichia coli was tested, as well as various physical parameters. Pot and block designs were found to exhibit similar pollutant removal performance for standard and high inflow concentrations, while the block design was more resistant to drying. However, due to its multiple practical advantages, pot designs are favoured. The greatest removal was achieved within the top green wall level for all studied pollutants, while subsequent levels facilitated further removal of TSS, COD, and TN. Interestingly, colour, pH, and EC increased after each green wall level, which must be taken into account to determine the maximum height of these systems. The optimal size of the system was found to be dependent on plant species choice. The results were used to create practical recommendations for the effective design of greywater treatment green walls.

Background The Revitalizing Informal Settlements and their Environments (RISE) programme aims to assess the health, wellbeing, and ecological impacts of a water-sensitive-cities approach to improving urban informal settlements. Incorporating water-cycle management and green technology sanitation strategies, we aim to reduce flood risk and improve sanitation and waste water treatment leading to cleaner and healthier environments. Here we present the initial design pre-intervention for evaluation in the first 12 settlements in Makassar, Indonesia. Methods Initial environmental, and wellbeing and human health assessments were implemented starting in October, 2018, in 12 settlements in Makassar, Indonesia. Ecological assessments include measuring of temperature and humidity via iButtons installed in select homes, recording of bio-acoustic to measure biodiversity within settlement boundaries, and trapping disease vectors quarterly. Implemented evaluation of environmental contamination includes sampling water and soil sources for total coliforms as well as collecting soil via bootsocks by walking predefined transects. Human assessment includes an annual baseline survey of all settlement households, assessing self-reported symptoms, health-care system utilisation, and subjective wellbeing. Additionally, children younger than 5 years are surveyed quarterly for caregiver reported symptoms of diarrhoea and febrile illness, blood samples and anthropometry are being collected annually, and faeces samples are requested quarterly. Findings Ecological assessments have provided more than a million temperature data points. 21 000 mosquitos have been captured and identified. A total of 114 water samples, 84 bootsocks, and 91 soil samples have been collected, with sampling prior to and during the wet season. We have identified over 600 households within the 12 settlements. Health assessments of children under the age of 5 years have revealed 282 children with collection of 234 faeces samples and 188 blood samples. Interpretation We have successfully implemented baseline ecological and human health and wellbeing assessment tools in all 12 settlements, which will allow for the evaluation of water-sensitive-cities approach in RISE programme. Funding The Wellcome Trust (Our Planet, Our Health grant 205222/Z/16/Z ).

Stormwater biofilters have great potential to treat stormwater for harvesting and reuse, but their variable performance in pathogen removal requires further optimisation prior to widespread uptake. This paper provides the first evidence that real time control (RTC) of stormwater biofilters can mitigate the impact of operational characteristics that result in poor microbial removal. We developed two RTC strategies and validated them using long-term laboratory experiments, utilising biofilters with a raised outlet pipe that creates a submerged zone. The first RTC strategy focuses on delivering the best water quality for harvesting and reuse or for recreational waterways. It has two components which ensure adequate treatment (microbial die-off): (1) it retains water in the biofilter for at least two days before allowing any further inputs into the system, and (2) the input volume is restricted to the submerged zone’s pore volume. This strategy was effective and significantly improved water quality in the biofilter effluent. However, since the system favours bypassing influent to ensure good quality effluent, only 28.4% of the stormwater was treated. This still resulted in a 62.3% reduction in the influent E. coli load because the system was effective at removing E. coli under controlled conditions. The second RTC strategy builds upon the first strategy, and focuses on delivering a balance between good water quality for harvesting and protecting the environment (i.e., lower bypass). Three hours before the next rainfall event begins, the water that has remained in the biofilter’s submerged zone for at least two days is drained and collected for harvesting through a bottom pipe. When stormwater inflow begins, the bottom pipe is closed and the biofilter operates without control, with water leaving the biofilter to the environment via the raised outlet pipe. The harvested effluent of this RTC strategy met the Australian stormwater harvesting guideline requirements for dual reticulation with indoor and outdoor use and irrigation of commercial food crops. Although only 5.4% of stormwater was collected for harvesting in this strategy, the environment was better protected because of a significantly reduced bypass volume. Our experiments also showed that the nutrient and sediment removal was high for both RTC strategies. This study presents the first stepping stone toward RTC of stormwater biofilters, demonstrating that these systems can deliver safe stormwater for harvesting and reuse, and for active recreational uses.