Sludge-drying lagoons are used in Australia as a convenient and cost-effective method of de-watering wastewater sludge. Methane emissions from these lagoons have been estimated to represent up to two thirds of total greenhouse gas emissions of the wastewater treatment, and will need to be addressed for water utilities to meet emission reduction targets. This project will investigate operational interventions that have the potential to select for novel microorganism capable of oxidising methane as a means of reducing emissions.

PhD Thesis completed by Sarah Aucote.

Algal systems can be used to decrease the concentration of nitrogen (N) and phosphorus (P) in wastewater to low levels, and hence reduce the harm of wastewater discharge and facilitate water reuse. This research contributed to the improvements of alginate-immobilised systems for wastewater treatment and demonstrated its technical feasibility for nutrient removal from different wastewaters. The findings can be used to guide how to best implement and integrate alginate-immobilised algae into new and existing wastewater treatment plants and can form the basis for viability assessment of its commercial application.

PhD Thesis completed by Matthew Kube in December 2019.

Conventional activated sludge (CAS) has been widely used for biological nutrient removal in the secondary treatment stage of the wastewater process for well over 100 years. Until recently, this technology has remained relatively unchanged until the emergence of aerobic granular sludge (AGS). This new technology has been identified as a potential replacement to the traditional microbial floc. AGS results in the biomass forming dense microbial granules with greater settling velocity, this can allow for greater volumes of wastewater to be treated by reducing the cycle times. This project will investigate several facets of the process  including impacts on water recycling (pathogen removal and tertiary disinfection), energy use or greenhouse gas emissions.

PhD Thesis completed by Benjamin John Thwaites in February 2021.

This research considered whether urban water governance, environmental regulation and recreational water quality management impact decisions to either reuse urban wastewater or dispose of it to the environment, and identifies opportunities for reform. Broader outcomes from the research included results being used to inform and support the establishment of a National Outfall Database as part of research by the Marine Biodiversity Hub under the National Environmental Science Programme (NESP).

PhD Thesis completed by Simon Clifford Perraton in June 2015.

Recycling wastewater by using reverse osmosis (RO) and ultrafiltration appears to be associated with the formation of some groups of micropollutants but there is not much information about these processes. This research selected iodinated disinfection by-products (DBPs) and N-nitrosamines (NDMA), and benzotriazoles and benzothiazoles, which are compounds in dishwasher detergents, for further investigation. It was concluded that minimising the formation of dichloramine (a precursor molecule to NDMA formation) by reducing pH and maximising activated sludge ammonia production, reduced the formation of N-nitrosamines in RO-treated wastewater. Iodinated DBPs and benzotriazoles were detected in RO treated wastewater in this study but at lower concentrations than those thought to pose a risk to human health.

Membranes are used to remove viruses from treated wastewater to make it safe for discharge or recycling. It is important to monitor the integrity of membranes and check that viruses cannot break through. This creates a need for surrogates that are cheaper, safer and easier to use than the non-hazardous indicator virus currently applied to test membrane integrity. This research synthesised a series of fluorescent nanoparticles with similar dimensions to viruses, with the idea that the fluorescence would support continuous in situ monitoring in real time, but unfortunately the nanoparticles did not emit enough fluorescence and could not be detected in the product water.

Smaller and regional Wastewater Treatment Plants (WWTPs) have the capacity to recycle wastewater for agricultural use, but the cost of obtaining regulatory approval or ‘accreditation’ is prohibitive. One reason for this is that each WWTP must demonstrate that its processes and operations consistently remove pathogens that cause infectious diseases in humans. Operating conditions include flow rate through the WWTP, and temperature in the activated sludge component of the WWTPs. Although pathogen ‘log removal values (LVR)’ were obtained for a WWTP at 19-20°C in Part I of this project (WQRA project 2001), these values cannot also be attributed to summer temperatures of 26°C. This research determined LRVs for ‘new’ WWTP operating conditions and combined the data with data from Phase I (Project 2001) for analysis. One of the conclusions from Part II was that faster flow rates associated with increased rainfall reduced pathogen LRVs.

The steam produced by boiling a kettle of salty water can be collected, condensed and drunk. Membrane distillation is an analogous process to this, but in this study the salty feedwater forms a salt-free vapour at a lower temperature; 30 – 40°C. The warm feedwater and vapour are pumped past a thin, porous membrane which repels liquid water but allows vapour to pass through the pores into a cold stream of freshwater on the other side. The vapour condenses and increases the volume of fresh, salt-free water. In this project an operational pilot plant was built and installed at an electricity generating station which produces waste heat and a stream of salty effluent that is normally discarded. The pilot plant was equipped with a 0.67m2 membrane, ran continuously for 3 months, and produced an average of 2.2L freshwater per hour. This equates to 3.4L/h/m2. The membrane area can be scaled up to increase production. It was concluded that this is a viable treatment technology for industrial wastewater that emits minimal greenhouse gasses.