By dewatering sludge, wastes can be efficiently and reliably concentrated into filter cakes with high solids for cost-effective disposal. Better understanding of the relationship between non-degradable organic matter and sludge rheology and dewaterability can lead to Optimization of dewatering which can significantly reduce the cost of wastewater treatment by minimizing the cost of sludge management, transportation, and final disposal.

PhD Thesis underway by Ali Tabatabaei.

Management of sewage sludge is an issue for Industry. Hydrothermal processing can be used to hydrothermally treat different kinds of sewage sludge such as primary, activated, and digested sludge and convert them into value added products such as hydrochar, biooil, aqueous phase and gas. This process will also be trialled on alum sludge and food and organic garden waste (FOGO). PFAS (Per and polyfluoro alkyl substances), another major concern of the water industry will be trialled to see if co-hydrothermal treatment can potentially degrade this emerging compound. This research will also investigate the techno commercial viability assessment of co-hydrothermal process.

PhD Thesis underway by Kamrun Nahar.

This project has four specific objectives: (1) To identify ways to prevent or reduce the incidence of foaming during anaerobic digestion of sewage sludge; (2) to identify the core microbiome associated with efficient digestor performance during stabilisation of sewage sludge; (3) to assess how changes in the reactor environment affect contaminant transformations; (4) to assess the impacts of biosolid post-treatments on the metabolic capacity of the microbial community, pathogen-survival, contaminant-transformations and ecotoxicology of final products.

PhD Thesis underway by Timothy Micallef.

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.

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.

Biosolids, the main by product from wastewater treatment plants, have a high potential in agricultural applications because they contain important plant nutrients and they can function as soil amendments. However, there are limitations to direct soil application of biosolids due to odour, pathogens, PFAS, micro-plastics, pharmaceuticals, and high heavy metal concentration present biosolids. This project proposes co-pyrolysis of biosolids with other waste types as a technique to overcome these limitations. In co-pyrolysis process, biosolids are mixed with other types of waste feedstocks and then are transformed thermochemically to biochar, pyro-oil, and pyro-gas in oxygen free atmosphere. This process is expected to overcome existing barriers in biosolids management and soil applications by transforming biosolids into high quality biochar with low heavy metal content and destroy PFAS components present in biosolids. In addition, co-pyrolysis also evidently improves qualities of oil and gas products due to the synergetic effects between the feedstock materials.

People excrete antibiotics and many types of bacteria, and this mixture can become concentrated in wastewater treatment plants. A specific part of the wastewater treatment process, ‘anaerobic digestion’, is particularly associated with the selection, emergence, and growth of antibiotic-resistant bacteria. These scientists want to find out if different ‘anaerobic digestion’ conditions are associated with increases, or decreases, in the numbers of antibiotic-resistant bacteria. They plan to find out by setting up relatively small, bench-sized anaerobic digesters in their laboratory, inoculating them with sludge from a full-scale working digester, then study the effects of different physico-chemical conditions on the incidence and frequency of DNA sequences of antibiotic-resistant genes and the ribosomal RNA sequences commonly used to identify different species of bacteria.

The ‘One Water’ paradigm recognises the interconnectedness of groundwater, stormwater, wastewater, flooding, water quality, wetlands, watercourses, estuaries, and coastal waters, and integrates multi-use, flexible and environmentally sustainable systems while valuing all urban water flows as a potential resource. Decades of water production, sewage treatment and urban development, have resulted in pipe and pump-station networks with the associated procedural systems for regulation and governance. Altogether, these form barriers to ‘One Water’ recycling and reuse. This research investigated, described, and defined these barriers and the strategies and actions used to overcome them. This was accomplished by reviewing published literature, by collating case studies and by recording the outputs of interactive workshops. It was concluded that obstacles to ‘One Water’ include the existing system of centralised and silo-ed expertise and the current complex structure of regulations governing safety of water supply, wastewater, and stormwater management. Research findings were used to develop a framework for transitioning to more flexible ‘One Water’ management processes which focus on integrated resource planning, incremental implementation, and the collaboration of traditional urban planners with water resource managers.