Australian Guidelines For Water Recycling Research Articles

Copper(II) hydroxide/oxide-coated granular activated carbon forE. coliremoval in water

AbstractLow-cost granular filter media with hybrid bacterial adsorption and survival inhibition capability is highly desired for the development of a low-impact water filtration system. In addition to overall removal, a deeper understanding of the fate and transport behaviour of bacteria in such systems should also be obtained to guide system operation. In this study, copper(II) hydroxide nanoparticles-modified granular activated carbon via a single-step in situ coating was prepared and denoted as CuH-G. Copper release behaviour and Escherichia coli removal efficiency of CuH-G were studied in saturated columns as a function of salinity, flow rate, and hydraulic loading. Copper release decreased exponentially on increasing salinity in test water, which potentiates controlled copper release for desired bacteria inhibition efficiency. With an effective contact time of 3.7 min, CuH-G provided 3.0 and 1.6 log E. coli removal in test water of salinity 237 and 680 μS/cm, respectively. Copper leaching at these two salinities were 1.7 and 0.74 mg/l, respectively below the Australian Guidelines for Water Recycling: Augmentation of Drinking Water Supplies. Further study of E. coli transport and deposition behaviour in heat-treated CuH-G at 160 °C revealed that the observed removal was largely attributed to enhanced attachment during filtration and survival inhibition post filtration.

A Review on the Current Knowledge and Prospects for the Development of Improved Detection Methods for Soil-Transmitted Helminth Ova for the Safe Reuse of Wastewater and Mitigation of Public Health Risks

Climate change, increase in population and scarcity of freshwater have led to a global demand for wastewater reuse in irrigation. However, wastewater has to be treated in order to minimize the presence of pathogens, in particular, the ova of soil-transmitted helminthes (STHs). Limiting the transmission via removal of STH ova, accurate assessment of risks and minimizing the exposure to the public have been recommended by health regulators. The World Health Organization (WHO) guideline specifies a limit of ≤1 ova/L for safe wastewater reuse. Additionally, the Australian Guidelines for Water recycling (AGWR) recommend a hydraulic retention time of over 25 days in a lagoon or stabilization pond to ensure a 4 log reduction value of helminth ova and to mitigate soil-transmitted helminths associated risks to humans. However, the lack of fast and sensitive methods for assessing the concentration of STH ova in wastewater poses a considerable challenge for an accurate risk assessment. Consequently, it has been difficult to control soil-transmitted helminthiasis despite effective mass drug administration. This limitation can be overcome with the advent of novel techniques for the detection of helminth ova. Therefore, this review presents an assessment of the current methods to detect the viable ova of soil-transmitted helminths in wastewater. Furthermore, the review focuses on the perspectives for the emerging state-of-the-art research and developments that have the potential to replace currently available conventional and polymerase chain reaction based methods and achieve the guidelines of the WHO in order to allow the safe reuse of wastewater for non-potable applications, thereby minimizing public health risks.

The influence of context and perception when designing out risks associated with non-potable urban water reuse

ABSTRACTPerceptions and cognitive bias in relation to reuse water can influence the responses to risk and reward. Much has been written on community perspectives and risk perceptions with regard to recycled water for non-potable use. This paper is distinct in that it focuses on the scheme proponents and those involved in designing and delivering schemes. An analysis of five case studies in Australia across a range of diverse settings revealed that the levels of treatment for various end-uses were in excess of the Australian Guidelines for Water Recycling. The evidence shows that the water industry has a fairly narrow view when identifying risks, and has an insurance type response to mitigating the risk. The overarching drivers for this are either the mitigation of the perceived risk associated with using reuse water, or the lack of an adaptive response to changes in the circumstances.

Stormwater constructed wetlands: A source or a sink of Campylobacter spp.

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.

Current Stormwater Harvesting Guidelines Are Inadequate for Mitigating Risk from Campylobacter During Nonpotable Reuse Activities.

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.

Validation of alkaline disinfection for recycled water schemes

Alcoa of Australia's recycled water schemes use a single chemical treatment process of alkaline disinfection. Recycled water schemes are approved by the Department of Health and are based on the water quality being fit for purpose and are assessed using the Australian Guidelines for Water Recycling (AGWR) 2006 and Department of Health WA Guidelines for the Use of Recycled Water in Western Australia (2011). However, the guidelines refer to residential and municipal recycled water uses and exposures and guidance refers to conventional, not alkali, disinfection.Disinfection with a chemical agent (e.g. chlorine, chloramine or, as in this case, caustic) requires some minimum effective concentration (often denoted C) and minimum contact time (often denoted T) to be effective. CT values are widely published for common disinfectants, but not for caustic. Therefore Alcoa completed microbial inactivation studies to establish a CT - equivalent for caustic and to determine whether the reference pathogens and microbial indicator organisms from the AGWR were relevant to the scheme.Despite the presence of a reasonably applicable guideline, the tasks undertaken at the Alcoa site were specifically assessed to help better estimate exposure since those given in the national guidelines were not necessarily intended to cover industrial uses. The microbial log reduction requirements of the scheme were determined using the default values stated in the Australian Guidelines for Water Recycling, as well as from using actual measured volumes from personal exposure monitoring. Margins of safety between alkaline disinfection capability and health requirements were identified and assessed.

Microbial risk assessment of drinking water to set health-based performance targets to improve water quality and treatment plant operations

Western Water (WW) provides water, recycled water and wastewater services to almost 150,000 people whilst continuously striving to improve processes to provide its customers with safe, cost effective and reliable drinking water, recycled water and treatment services. Under this framework of continuous improvement, WW has reviewed the effectiveness of its drinking water treatment systems using quantitative microbial risk assessment (QMRA) techniques described by the World Health Organization (WHO). The microbial-related water quality targets in the Australian Drinking Water Guidelines Paper 6 National Water Quality Management Strategy (2011) National Health and Medical Research Council, National Resource Management Ministerial Council, Commonwealth of Australia, Canberra are simply ‘to ensure that drinking water is free of microorganisms that can cause disease’. Whereas, the Australian Guidelines for Water Recycling adopted the WHO QMRA approach for setting health-based microbial targets to manage health risk to customers. WW has investigated adopting the AGWR methodology for drinking water risk management, and invested in the development of a convenient and practical QMRA tool for rapid assessment and reporting of the microbial safety of its drinking water systems. This action resulted in the identification of several drinking water system performance deficiencies, and recommendations for system improvements and optimization to improve health risk management to customers.

Water reclamation and nitrogen extraction from municipal solid waste landfill leachate

This study aims to explore several innovative technologies including electrocoagulation, nanofiltration (NF), membrane distillation (MD), and ion exchange resin for clean water extraction and resource recovery from landfill leachate. Our results demonstrate the technical feasibility of water reuse and ammonia recovery from landfill leachate. Electrocoagulation was effective as a pretreatment step for the NF process and could remove most suspended solids and some organic matter. The results show that the combination of NF and MD can produce high-quality water from landfill leachate suitable for reuse applications with respect to heavy metals (with the exception of arsenic) and pharmaceutically active compounds (PhACs). Heavy metal concentrations in the NF permeate were below the values specified by the Australian Guidelines for Water Recycling. PhAC removals by the NF process were in the range of 67–97%. Heavy metals and PhACs were not detectable in the MD distillate. The recovery of ammonia from NF permeate by a strong acid ion exchange resin was also demonstrated.

Effect-based trigger values for in vitro bioassays: Reading across from existing water quality guideline values

Cell-based bioassays are becoming increasingly popular in water quality assessment. The new generations of reporter-gene assays are very sensitive and effects are often detected in very clean water types such as drinking water and recycled water. For monitoring applications it is therefore imperative to derive trigger values that differentiate between acceptable and unacceptable effect levels. In this proof-of-concept paper, we propose a statistical method to read directly across from chemical guideline values to trigger values without the need to perform in vitro to in vivo extrapolations. The derivation is based on matching effect concentrations with existing chemical guideline values and filtering out appropriate chemicals that are responsive in the given bioassays at concentrations in the range of the guideline values. To account for the mixture effects of many chemicals acting together in a complex water sample, we propose bioanalytical equivalents that integrate the effects of groups of chemicals with the same mode of action that act in a concentration-additive manner. Statistical distribution methods are proposed to derive a specific effect-based trigger bioanalytical equivalent concentration (EBT-BEQ) for each bioassay of environmental interest that targets receptor-mediated toxicity. Even bioassays that are indicative of the same mode of action have slightly different numeric trigger values due to differences in their inherent sensitivity. The algorithm was applied to 18 cell-based bioassays and 11 provisional effect-based trigger bioanalytical equivalents were derived as an illustrative example using the 349 chemical guideline values protective for human health of the Australian Guidelines for Water Recycling. We illustrate the applicability using the example of a diverse set of water samples including recycled water. Most recycled water samples were compliant with the proposed triggers while wastewater effluent would not have been compliant with a few. The approach is readily adaptable to any water type and guideline or regulatory framework and can be expanded from the protection goal of human health to environmental protection targets. While this work constitutes a proof of principle, the applicability remains limited at present due to insufficient experimental bioassay data on individual regulated chemicals and the derived effect-based trigger values are of course only provisional. Once the experimental database is expanded and made more robust, the proposed effect-based trigger values may provide guidance in a regulatory context.

Assessment of treatment options of recycling urban stormwater recycling via aquifers to produce drinking water quality

With the release of the Australian Guidelines for Water Recycling: Managed Aquifer Recharge (MAR), aquifers are now being considered as a treatment barrier when assessing the human health risk of recycled water systems. An MAR research site recharging urban stormwater in a confined aquifer was used in conjunction with a quantitative microbial risk assessment to assess the microbial pathogen risk in the recovered water for drinking. The assessment involved undertaking a detailed assessment of the treatment steps and exposure controls, including the aquifer, to achieve the microbial health-based targets.

Nutrient and trace organic contaminant removal from wastewater of a resort town: Comparison between a pilot and a full scale membrane bioreactor

The occurrence of a broad spectrum of trace organic contaminants (TrOCs) in raw sewage from a small resort town and their removal by a full- and a pilot-scale membrane bioreactor (MBR) was analysed in this study. The MBR systems demonstrated similar reduction of chemical oxygen demand. However, the full-scale MBR sustained higher and more stable nutrient removal (>95% for both total nitrogen, TN and phosphate, PO43−-P) than the pilot-scale system (ca. 80% TN and 30% PO43−-P removal). Of the 45 monitored TrOCs including pharmaceuticals and personal care products (PPCPs), industrial chemicals, steroid hormones, and pesticides, 41 compounds were detected in the raw sewage above detection limits of 5–20 ng L−1. A correlation between the removal of TN and eight TrOCs (atenolol, caffeine, naproxen, ibuprofen, gemfibrozil, DEET, estrone and diuron) was observed. Additionally, the full-scale MBR demonstrated higher and/or more stable removal for sulfamethoxazole, trimethoprim, diclofenac, diuron and amitriptyline. With the exception of caffeine, estrone and triclosan, TrOC concentrations in MBR effluent were lower than the Australian Guidelines for Water Recycling: Augmentation of Drinking Water Supplies.

Validation of the Goreangab Reclamation Plant in Windhoek, Namibia against the 2008 Australian Guidelines for Water Recycling

Australia has had Guidelines in place for water recycling (for all uses other than the augmentation of drinking water supplies) since 2006. These Guidelines were extended to cover potable reuse in May 2008 and have been applied to two potable reuse projects in Australia – one a trial plant in Perth, Western Australia and the second for a large AUD$2.6 × 109 scheme in Brisbane, Queensland. All reclamation plants in Australia must be ‘validated’ against the Australian Guidelines for Water Recycling prior to being put into operation. The majority of advanced reuse schemes incorporate the dual membrane process – microfiltration or ultrafiltration followed by reverse osmosis (RO) – in the treatment trains and while this membrane based treatment has been shown to produce a very high quality of product water, it does come at a cost and there is renewed interest in alternative treatment technologies that offer cost savings and are more sustainable. This paper uses data gathered in Australia from a range of advanced reclamation plants, as well as design and actual performance criteria from the Goreangab Plant, to ‘validate’ the latter and, given the longevity of the Windhoek direct potable reuse experience, lend support to more serious consideration of non-RO based plants for potable reuse applications.

The development, application and acceptance of environmental and health risk assessment methodology for MAR schemes in South Australia

A risk assessment methodology for the establishment of Managed Aquifer Recharge (MAR) schemes has evolved in South Australia (SA) over the last 6 years. The methodology is based on the Australian Guidelines for Water Recycling and has been led by the Environment Protection Authority (EPA) in close collaboration with the Department of Environment, Water and Natural Resources (DEWNR), Department of Health and Aging (SA Health) and industry. MAR has been established in SA as a common practice over the last 20 years. Early Aquifer Storage and Recovery (ASR) schemes were supported and initiated by DEWNR (in various guises) to explore viability and recharge depleting aquifers. Large areas of the Adelaide Plains, across where the state’s capital sprawls are underlain by a tertiary aquifer system that lends itself to MAR. Local councils and catchment boards embraced the practice and the Commonwealth Scientific and Industrial Research Organisation Land and Water proceeded with an extensive programme of research and documentation of existing and emerging MAR practices. ASR of treated wastewater was trialled and a pilot scheme established by SA Water which is now operational. Early schemes were not rigorously regulated but up to five state agencies are now involved because of their legislative responsibilities. DEWNR regulates water quantity, EPA water quality and SA Health the impact of use on human health. Most of the legislation was written prior to MAR practices and has been applied adaptively providing confusion and frustration for developers and operators. MAR schemes have proved successful and the number continues to increase boosted over the last 10 years by federal government initiatives promoting the use of recycled water, funding support and an extended period of drought. The Australian Guidelines for Water Recycling: Managing Health and Environmental Risks 2006 and Phase 2 Guidelines were developed detailing a health and environmental risk assessment framework that could be applied to recycled water schemes including MAR. The risk assessment methodology follows a stepwise approach to examining the source water, the receiving aquifer and the end-use. The requirements for developers and operators have increased over time and the risk assessment processes are now embraced and a Draft MAR Guide has been developed. There has been a collaborative effort by the agencies involved to streamline the process and the risk assessment methodology is a key binding force. Industry acceptance has not been smooth, adaption of regulation is ongoing, monitoring has been inconsistent and unexpected technical and water quality issues continue to arise; however, there are number of loose ends remaining to be tied.

Which chemicals drive biological effects in wastewater and recycled water?

Removal of organic micropollutants from wastewater during secondary treatment followed by reverse osmosis and UV disinfection was evaluated by a combination of four in-vitro cell-based bioassays and chemical analysis of 299 organic compounds. Concentrations detected in recycled water were below the Australian Guidelines for Water Recycling. Thus the detected chemicals were considered not to pose any health risk. The detected pesticides in the wastewater treatment plant effluent and partially advanced treated water explained all observed effects on photosynthesis inhibition. In contrast, mixture toxicity experiments with designed mixtures containing all detected chemicals at their measured concentrations demonstrated that the known chemicals explained less than 3% of the observed cytotoxicity and less than 1% of the oxidative stress response. Pesticides followed by pharmaceuticals and personal care products dominated the observed mixture effects. The detected chemicals were not related to the observed genotoxicity. The large proportion of unknown toxicity calls for effect monitoring complementary to chemical monitoring.

Urban stormwater harvesting and reuse: a probe into the chemical, toxicology and microbiological contaminants in water quality

Stormwater is one of the last major untapped urban water resources that can be exploited as an alternative water source in Australia. The information in the current Australian Guidelines for Water Recycling relating to stormwater harvesting and reuse only emphasises on a limited number of stormwater quality parameters. In order to supply stormwater as a source for higher value end-uses, a more comprehensive assessment on the potential public health risks has to be undertaken. Owing to the stochastic variations in rainfall, catchment hydrology and also the types of non-point pollution sources that can provide contaminants relating to different anthropogenic activities and catchment land uses, the characterisation of public health risks in stormwater is complex, tedious and not always possible through the conventional detection and analytical methods. In this study, a holistic approach was undertaken to assess the potential public health risks in urban stormwater samples from a medium-density residential catchment. A combined chemical-toxicological assessment was used to characterise the potential health risks arising from chemical contaminants, while a combination of standard culture methods and quantitative polymerase chain reaction (qPCR) methods was used for detection and quantification of faecal indicator bacteria (FIB) and pathogens in urban stormwater. Results showed that the concentration of chemical contaminants and associated toxicity were relatively low when benchmarked against other alternative water sources such as recycled wastewater. However, the concentrations of heavy metals particularly cadmium and lead have exceeded the Australian guideline values, indicating potential public health risks. Also, high numbers of FIB were detected in urban stormwater samples obtained from wet weather events. In addition, qPCR detection of human-related pathogens suggested there are frequent sewage ingressions into the urban stormwater runoff during wet weather events. Further water quality monitoring study will be conducted at different contrasting urban catchments in order to undertake a more comprehensive public health risk assessment for urban stormwater.

Water recycling in Western Australia: analysis of 2003–2009 water quality monitoring programme

Water-recycling schemes have been in operation in Western Australia since 1960. As a requirement of the regulatory framework for wastewater reuse, periodic water quality monitoring has been implemented to demonstrate microbial compliance for the intended end-use. For this study, we originally planned to analyse the compliance of the 92 water recycling schemes in the database over a 7 year period (2003–2009); however, it was necessary to exclude 21 schemes because they either lacked sufficient data or their recording standards were too inconsistent for the analysis. Compliance was analysed by comparing: (i) the observed microbial results against the quality criteria and (ii) the number of samples analysed against the expected number of samples based on regulatory frequency requirements. The results indicate that 12% of the remaining 71 schemes analysed did not comply with water quality criteria over the 7 year period, and most of the original 92 recycling schemes did not comply with the expected number of samples. Challenges faced by existing schemes in conforming to the Australian Guidelines for Water Recycling: Managing Health and Environmental Risks (Phase 1) (2006) and the Guidelines for the Non-Potable Uses of Recycled Water in Western Australia (2011) are discussed.

Removal of trace organic chemical contaminants by a membrane bioreactor

Emerging wastewater treatment processes such as membrane bioreactors (MBRs) have attracted a significant amount of interest internationally due to their ability to produce high quality effluent suitable for water recycling. It is therefore important that their efficiency in removing hazardous trace organic contaminants be assessed. Accordingly, this study investigated the removal of trace organic chemical contaminants through a full-scale, package MBR in New South Wales, Australia. This study was unique in the context of MBR research because it characterised the removal of 48 trace organic chemical contaminants, which included steroidal hormones, xenoestrogens, pesticides, caffeine, pharmaceuticals and personal care products (PPCPs). Results showed that the removal of most trace organic chemical contaminants through the MBR was high (above 90%). However, amitriptyline, carbamazepine, diazepam, diclofenac, fluoxetine, gemfibrozil, omeprazole, sulphamethoxazole and trimethoprim were only partially removed through the MBR with the removal efficiencies of 24-68%. These are potential indicators for assessing MBR performance as these chemicals are usually sensitive to changes in the treatment systems. The trace organic chemical contaminants detected in the MBR permeate were 1 to 6 orders of magnitude lower than guideline values reported in the Australian Guidelines for Water Recycling. The outcomes of this study enhanced our understanding of the levels and removal of trace organic contaminants by MBRs.

Microbiological risks of recycling urban stormwater via aquifers

With the release of the Australian Guidelines for Water Recycling: Managed Aquifer Recharge (MAR), aquifers are now being included as a treatment barrier when assessing risk of recycled water systems. A MAR research site recharging urban stormwater in a confined aquifer was used in conjunction with a Quantitative Microbial Risk Assessment to assess the microbial pathogen risk in the recovered water for different end uses. The assessment involved undertaking a detailed assessment of the treatment steps and exposure controls, including the aquifer, to achieve the microbial health-based targets.

Aquifer recharge to assist in the management of produced CSG water

Santos is producing natural gas and expanding its CSG operations in the Surat and Bowen Basins, Queensland for the Gladstone Liquefied Natural Gas (GLNG) project. During the project, it has been estimated that a total of ∼340 GL of associated water could be produced from gas extraction in three CSG fields. Beneficial re-use of this water is a high priority and one option involves treating the water and re-injecting it into the water supply aquifers in the Great Artesian Basin. In the past 100 years, groundwater pressures in the Gubberamunda Sandstone aquifer, Roma’s main town water supply, have declined more than 80 m and groundwater demand for the town water supply is now more than 5 ML/day. This demand, coupled with forecast droughts in modelled climate change scenarios, provides an impetus for the beneficial re-use of treated produced water. To assess the feasibility of the aquifer for managed aquifer recharge (MAR), a risk-based framework consistent with the Australian Guidelines for Water Recycling: Managed Aquifer Recharge was applied. A series of assessment stages designed to protect human health and the environment were undertaken, each allowing a decision point for investment. To date, a MAR well-field has been developed and numerous hydraulic tests have been undertaken along with laboratory/desktop evaluation of the geochemical compatibility of the injected water with the water and sediment of the target aquifer. An injection trial in Q4 2011 will evaluate the aquifer storage potential and confirm numerical/laboratory studies related to hydraulics and water quality compatibility.

The adoption of the Australian Water Recycling Guidelines by regulators with specific reference to treatment validation requirements

Australian Guidelines for Water Recycling: Managing Health and Environmental Risks (Phase 1) (AGWR) were published in 2006 and present a risk management framework. A major component is the validation of a treatment process for log removal of microorganisms. A National Water Commission (NWC) Fellowship looked at the adoption of the AGRW and the validation requirements of the individual jurisdictions within Australia. To enhance the uptake of recycled water, reduce the technical burden on jurisdictions and promote consistence between jurisdictions, three recommendations were proposed: 1. Agree that treatment systems for low exposure schemes be exempt from individual validation; 2. Develop a national database for log removal values for use with low exposure schemes; and 3. Develop a national approach to the validation of treatment processes. A process for achieving these goals is outlined in the paper.