It is well understood NOM character as well as concentration impacts its treatability by water treatment processes and that concentration and character can change over time. This project will develop and evaluate novel, advanced characterisation and in situ monitoring techniques to provide NOM character, and in turn, will determine the link between NOM character and treatment performance.

PhD Thesis underway by Anthony Agostino.

This project investigated the relationship between disinfection by-product (DBP) formation in drinking water and the molecular weight distribution of its natural organic matter precursors (NOM) to help increase our understanding of how NOM properties such as size, aromaticity and structure affect DBP formation and toxicity of the formed DBPs.

Honours Thesis completed by Sophie Day in 2012.

This project developed an understanding of the occurrence of regulated and emerging disinfection by-products (DBPs) in drinking water in Southeast Queensland (SEQ). This was achieved through the characterisation of natural organic matter of several SEQ source waters and through exploring strategies for halide and organic matter DBPs precursor removal from water, and examining the effect of these removal strategies on DBPs formation.

Honours Thesis completed by Kalinda Watson in October 2014.

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.

The environmental conditions which cause blue-green algae (cyanobacteria) blooms vary according to location, the climate, and other attributes of aquatic ecosystems. This variety has made it difficult to develop one broadly applicable predictive model for cyanobacterial blooms. Water utilities monitor source waters to implement cyanobacterial risk management programmes but there are no standard protocols while limited information transfer between utilities has prevented the identification of management strategies that do or do not work. This research reviewed literature about early warning systems (Almuhtaram et al., 2021) and source control strategies, conducted a survey of 35 utilities in America and Canada (74%) and Australia (Kibuye et al., 2021) and evaluated selected control strategies. These different types of information were synthesised into decision trees within an overarching guidance document. It was concluded that a 3-tier framework to detect algal blooms which monitored biological activity, then confirmed the identification of cyanobacterial genes and associated metabolites gave sufficient early warning, while multi-barrier control strategies gave field-scale efficacy and enabled timely responses.

N-nitrosodiumdimethylamine (NDMA) in drinking water is one of many factors – such as a persons’ genes – that cause cancer. Although NDMA is not a sole cause of cancer, the water industry aims to minimise its contribution to illness and disease. This research measured levels of NDMA in drinking and recycled waters and found the majority well below the Australian Drinking Water Guideline values that are considered safe for public consumption. Different sources of NDMA were identified and water monitoring and treatment strategies to optimise NDMA removal from source waters were recommended.

Disinfection is essential for removing harmful microbial pathogens and making safe drinking water but can also cause formation of disinfection by-products (DBPs), some of which pose a health risk. Thirty years of research have amassed a wealth of knowledge about the identification, formation, treatment and control, toxicology and epidemiology of DBPs in Australia. This project compiled, assessed and presented an overview of DBP-related research in Australia.

Water treatment plant operators remove cyanobacteria and the toxins they produce from source waters but calculating the amount of treatment needed for effective removal is difficult, particularly in bloom conditions when cyanobacterial cell numbers and toxins change quickly. Current cell counting and toxin measurement can take hours or days to complete, and the results are not available quickly enough to help treatment plant operators respond to changing conditions. There is a need for a real-time method that gives instant results. This research examined the utility of fluorometers; probes that emit light that is ‘reflected’ back at different wavelengths by living cells and other matter in the water and is detected by the fluorometer. It was found that when only one species of cyanobacteria was present, there was a good correlation between the fluorescent signal and cell number, particularly when source waters were clear and not cloudy. Cell numbers did not relate well to levels of toxins or taste and odour compounds. When fluorometers were installed in 13 water treatment plants the correlation between cyanobacteria cell numbers and fluorometer signals was validated, and this led to the conclusion that fluorometers can give early warning of blue-green algae blooms.

Natural organic matter (NOM) and bromide in source waters react with disinfectants to produce disinfection by-products (DBPs) in drinking water. This research quantified NOM and bromine in raw water and after coagulation treatment with alum. Neither raw nor alum-treated water were toxic in two laboratory tests. This research used a new site to confirm previous findings (Project 1041) that coagulation reduces DBP formation and toxicity after chlorination.

Blue-green algae (cyanobacteria) reduce water quality especially when they bloom and form high numbers of cells which produce toxins, and taste and odour compounds. Most cyanobacteria photosynthesise and tend to grow and float at depths which optimise their exposure to sunlight, but an increase in unexplained occurrences of taste and odour compounds in reservoirs, and a bloom of benthic (bottom-living) cyanobacteria, forced the closure of a water supply. This research examined the role that bottom-living benthic cyanobacteria play in the production of toxins or taste and odour compounds. Seven DNA-based PCR tests were developed to identify benthic species of cyanobacteria and their capacity for producing toxins. A taste and odour compound, and two toxins were found in winter and spring in an SA reservoir, whereas a different taste and odour compound and toxin assemblage were found in summer and autumn in a reservoir in NSW. These results will help water suppliers to anticipate and manage future aesthetic or toxin issues related to benthic cyanobacteria.