Raw source water contains parts of plants, blue-green algae and their toxins, and many other types of organic matter. Identifying the types and amounts of organic matter helps treatment plant operators make informed decisions about the most efficient and cost-effective methods for treating and removing unwanted substances from source waters. The problem is that many of the tests for identifying organic compounds can take hours to days to deliver results. This research developed a test that gives information immediately. It uses three commercially available fluorescent probes that each emit fluorescent light at a specific wavelength. Certain compounds within organic matter, such as proteins, “reflect” the fluorescent light, but at different wavelengths which can be detected by the probes. These patterns of “reflected” fluorescence were related to traditional tests for organic compounds. This on-line fluorescence monitoring was then trialled at real-world treatment plants. The patterns gave reliable information about broad categories of organic compounds and there was a linear correlation between dissolved organic carbon and fluorescent intensity in both raw and treated waters. This research has provided a valuable addition to the suite of tools available for producing safe, high quality drinking water.

Reverse osmosis (RO) is used to desalinate seawater and brackish groundwater, and to remove microscopic pathogens from treated wastewater. The salty water is pressurised on one side of the RO membrane and this is part of the process that results in water molecules passing (diffusing) through the membrane to the lower pressure solution on the other side. Salts such as sodium chloride (table salt) and calcium sulphate and calcium carbonate (scale) do not diffuse easily across the RO membrane and build up on the high-pressure side. Eventually scale deposition on the membrane prevents the diffusion of water molecules and the production of freshwater declines. This research tested four commercial and three in-house antiscalent chemicals, and additionally developed a technique to monitor scale formation and RO membrane performance in real-time. It was concluded that the antiscalent ‘PC-191T’ was best and that adding an ‘Electrical Impedance Spectroscope’ to RO systems has the potential to deliver a sensitive in-situ, real-time monitoring method capable of detecting very early scale formation, well before membrane performance declines. This will enable optimisation of membrane scale removal and improve the efficiency of freshwater production.

Sewage is delivered to wastewater treatment plants (WWTPs) where benign microbial organisms within ‘activated sludge’ vessels contribute to the removal of harmful pathogens from the sewage. The activity and pathogen-removing ability of these helpful organisms is affected by many factors including temperature, numbers of fine particles, pH, ammonia, and the time available to remove the pathogens. Regulatory authorities require at least 90% (one log removal value, LRV) of the pathogens to be removed, but as WWTP operating conditions vary, the LRVs change. This problem led to recognition of the need to develop models capable of predicting relationships between plant operating parameters (such as temperature) and pathogen removal. This research reviewed published reports and datasets, then set up and ran an experimental activated sludge pilot plant to generate data about a range of operating conditions and pathogen removals. These datasets were used to develop models which had only a ‘poor’ predictive value for clostridia but were ‘good’ for giardia and ‘very good to excellent’ for the removal of other pathogens. These models need to be extended with more operating conditions but have the potential to be used to attribute LRVs and for future integration into online real-time monitoring.

The ADWG explains policies but does not provide the specific steps and actions needed to apply risk management principles within a water treatment plant (WTP). The original ‘Guide to Drinking Water Supply Systems for the Management of Microbial Risk’ (WaterRA Project 1074) filled this gap by providing Australian-specific advice about managing and optimising common water treatment processes to achieve microbial health-based targets. Since its publication in 2015 it has become a popular reference document, and its widespread acceptance and use has prompted the production of this second edition. Included are updated technologies and regulations, and a series of auditing tools and templates for application in a variety of situations, including the identification and quantification of risk.

Click here to download the Good Practice Guide.

Cyanobacteria (blue-green algae) which float in reservoirs have been studied for decades because when they bloom, the very high cell numbers cause a problem for water treatment plant (WTP) operators, who have to remove the cells, toxins, and taste and odour compounds they produce. Benthic, bottom-living cyanobacteria which also produce toxins were recently discovered in Australian reservoirs. The problem is that benthic cyanobacteria are not included in routine monitoring practices and very little is known about them. This research provided information about the incidence of benthic cyanobacteria and the toxins they produce in various catchments; identified environmental conditions that stimulate bloom formation, and investigated naturally occurring biodegradation of taste and odour compounds. It was concluded that there is a need to monitor benthic cyanobacterial mats to ascertain the risk they pose, and to obtain additional in-situ data about more benthic species, because this will support the construction of predictive models to facilitate improved management of catchment and source waters.

Microbial pathogens are removed from source waters to make safe drinking water. Health-based targets (HBTs) refer to the quantities of pathogens that will NOT cause illness, and water treatment plants (WTPs) must ensure that the numbers of pathogens in potable water are the same or lower than the HBTs. WTP operators select the best pathogen removal treatment for a range of conditions such as season, rainfall and agricultural activity by referring to ‘sanitary surveys’. These are carried out approximately once a year by scientists driving and walking in the source water catchment, making observations, and collecting samples which are examined to look for indicators of harmful pathogens. Recent requirements to achieve HBTs, combined with technological advances, led to this project which aims to provide flexible sanitary survey guidance applicable to the broad range of Australian conditions and utilities. This Good Practice Guide reviews existing procedures, describes modern methods including aerial photography and the use of spatial databases, and describes the incorporation of sanitary surveys into ongoing source water operational monitoring in ways that support the establishment of log removal values and enable compliance with HBTs.

A survey of water utilities identified the top five challenges faced in daily operations, and technical, economic and literature reviews identified remote sensing strategies and technologies to address these five operational issues. The need for, and benefits of real-time monitoring which facilitates cost-effective and efficient responses to rapidly changing conditions, were common to all five challenges, which were: monitoring cyanobacteria and their metabolites, the effects of contamination and extreme climate-change driven events on water quality, the variation in climatological data over relatively small distances (need to increase focus, precision and produce ‘finer’ datasets for reservoir management), asset inspection and management and monitoring catchments for a variety of factors. This research evaluated and explained the solutions, strengths, weaknesses, and costs of products best suited for addressing each challenge.

The management of blue-green algae (cyanobacteria), and the toxins and taste and odour compounds they produce, have been the focus of more than 30 years of research, but there is still a need for a suite of user-friendly tools to assess and manage aesthetic and toxin risks. This project conducted an extensive literature review about the ability of six treatment paradigms to remove MIB, geosmin, saxitoxins, microcystins and cylindrospermopsin. An empirical spreadsheet-base model was then built and used to simulate ‘whole-of-plant’ removal of cells and toxic metabolites. This model performed well when tested with two years of full-scale sampling data.

Although water utilities recognise the value of online instruments that provide real-time monitoring capability, there are problems with visualising and interpreting datasets, and with distinguishing between data resulting from real-world changes in treatment plant operating conditions, for example changed turbidity or flow, and instrument failure. There are also challenges around instrument installation and operation. This project developed tools to support data visualisation and interpretation by building a prototype visualisation platform for analysing complex online UV spectral data in conjunction with weather and lab data (see Factsheet 2 ‘Development of an online platform’). To improve differentiation between instrument failure and real-world data a Bayesian Belief Network model was developed to analyse patterns and variations within datasets. Real operational, high turbidity data was used to demonstrate that this model could accurately identify different causes for the readings which included filter ripening, backwash and other causes (see Factsheet 3 ‘Improving decision making in water plant operability through Bayesian Belief networks’). Strategies for instrument installation and operation were illustrated through case studies.

The ADWG prioritises the removal of microscopic pathogens (and the toxins some produce) from public drinking water supplies to prevent large scale outbreaks of illness. This principle underlies the importance of adhering to consistently high standards of water treatment plant (WTP) operation and maintenance. This Guide refers primarily to the conventional WTP processes of chemical pre-treatment, coagulation, flocculation, clarification, filtration and disinfection; and establishes target criteria and critical limits for each step in the treatment process. The Guide is designed to provide water utility managers and operations staff with a concise reference document to optimising the WTP processes that produce microbially-safe drinking water and additionally supports the establishment of microbial Health-based targets.