Harmful pathogens and compounds must be removed from wastewater before it can be discharged to the environment or used for irrigation, and many source waters need salts removed to make them potable. Microfiltration and ultrafiltration membranes remove pathogens and unwanted chemicals but as they are used, they become fouled and blocked by particulates and compounds from the water being filtered, as well as by the formation of biofilm, and by chemical interactions between solutes and the membrane materials. Although the membranes are cleaned regularly, the cleaning chemicals themselves can cause a problem. This research characterised the damage that various cleaning regimens inflict on membranes made of different materials and examined the effects of progressive and consecutive stages of membrane aging and degradation on performance. It was concluded that the type of cleaning agent affects the mechanism of membrane degradation and the severity of membrane integrity loss. More information is needed regarding the cleaning protocols and agents used in industry. Information from this research can inform a generally applicable model to predict membrane aging and decline in performance.

European carp have decimated native fish species in the Murray-Darling River. The federally funded National Carp Control Plan proposes using a carp-specific virus to kill the pest-fish, but before doing so are consulting with a broad array of environmental, conservation and other stakeholders, including the water industry. There are concerns that large amounts of dead and decaying carp near water offtakes or storages might overwhelm the capacity of water treatment plants (WTPs) to remove organic matter and taste and odour compounds, and might compromise the production of safe, palatable drinking water. In this research a series of experiments led to the conclusions that medium to high carp densities could be managed by adding a 30 minute procedure to existing WTP methods, and that there would not be an increased risk to public health.

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.

The filters in some water treatment plants have a biofilm of bacteria which degrades and removes cyanotoxins. This natural biodegradation is a cost-effective and sustainable addition to the methods used to produce safe drinking water. This research examined the parameters controlling the process with a view to establishing biodegradation in other treatment plants. It was concluded that if filter beds with small particle sizes are seeded with degrading bacteria, an effective biofilter can form if pre-chlorination is avoided and if cyanotoxins are present in the inflowing source water.