Projects

The properties of concentrated sludge arising from increased pressure on the capacity of wastewater treatment plants are being investigated in this project.

Growing urban populations means that wastewater treatment plants are under pressure to treat increasing volumes of wastewater within existing plants. This means that the sludge that circulates in the anaerobic digesters is more concentrated.  The rheological characteristics of concentrated sludge are harder to predict, and this reduces the efficiency of the system. The rheological behaviour of sludge plays a key role in anaerobic digestion process performance. Better understanding of the evolution of shear rheological and solid-liquid separation properties of anaerobic digested sludge is critical for optimizing the digestion process to maximise biogas production and improve digestate dewaterability.

The Rheology group at RMIT develops rheological models and solid-liquid separation (dewaterability) parameters as continuous functions of solids concentration, extent of digestion and digestion temperature suitable for modelling low to high solid anaerobic digestion processes. Further details can be obtained from Professor Nicky Eshtiaghi.

Biosolids, the stabilised sewage sludge produced from wastewater treatment facilities, are a growing concern as they contain pathogens as well as several contaminants such as per- and poly-fluoroalkyl substances (PFAS), microplastics and pharmaceuticals.

The team of researchers from the WETT Centre led by Prof Kalpit Shah in collaboration with South East Water, Intelligent Water Networks and Greater Western Water is developing a novel RMIT patented biosolids treatment technology - PYROCO - aiming to produce biochar with safe destruction and removal of contaminants including PFAS, and so provide the wastewater industry a biosolids management solution.

The pilot demonstration phase of the project, recently completed, has successfully demonstrated that PYROCO can produce high quality contaminant-free biochar with very high process efficiencies. This project won the Australian Water Association VIC Water Award for R&D Excellence in March 2022.

A WETT Centre team led by Prof Kalpit Shah collaborated with the University of Newcastle and several water and allied industries across Australia to develop novel immobilisation, adsorption and/or thermal destruction methods for biosolids, soil and groundwater in current and legacy PFAS sites receiving biosolids.

This project has provided the first major detailed investigation of the release, fate and remediation of perfluorinated compounds in relation to their environmental pathways through wastewater treatment plants in Australia. Several new immobilisation and thermal destruction methods have been developed as part of this investigation.

This work was funded under the Special Research Initiative grant scheme of the Australian Research Council.

A one-million-dollar ARC Linkage project in partnership with Melbourne Water and Water Corporation (Western Australia) aims to investigate the rheology and fluid mechanics of highly concentrated wastewater sludges and develop tools to support effective pipeline designs for wastewater treatment plants.

The project team, led by Professor Nicky Eshtiaghi, expects to generate new knowledge about the complex flow of concentrated wastewater which will enable predictive models to support the design and optimization of pipeline transport systems. Expected outcomes of the project include a new toolkit that will enable wastewater treatment plants to design and optimize both existing and future pipeline systems. This will support the Australian wastewater industry to plan for future growth, increase throughput and efficiency, reduce environmental pollutants, and capital and operating costs.

A limited version of the upcoming toolkit was recognised in the Engineers Australia’s magazine create listing of Most Innovative Engineers for 2020.

Climate change impacts and reduced fresh water sources are forcing utilities to utilise alternative water sources within the concept of the circular economy. Current tools do not allow utilities to predict the removal of chemicals of emerging concern (CECs) in wastewater treatment lagoons and so enable assessment of the risk of the treated water and optimisation of the treatment process. Of the 1,234 wastewater treatment plants in Australia, 950 utilise lagoon treatment.

To address compliance with new demanding regulations for varying sources utilities need a cost-effective tool to identify the most problematic CECs and their removal in natural treatment processes.

Sunlight-induced photodegradation followed by chemical and/or biological breakdown is a major removal pathway for trace organics in both surface water and wastewater lagoons. The photodegradation of CECs depends on their structure, whether it is via direct or indirect photolysis, and WETT researchers have shown it occurs to varying degrees depending on wastewater matrix properties, temperature and sunlight irradiance, all of which vary with season. The relationships between the variables are highly complex and non-linear requiring a new approach to elucidate the correlations between the lagoon wastewater and plant performance to enable prediction of CEC removal.

Building on the correlations we have already determined, a chemoinformatic software model which will enable prediction of the photolytic removal of CECs during lagoon wastewater treatment will be developed. The model will take into account CEC structure and the impact of the wastewater characteristics, temperature and irradiance. This work is supported by Melbourne Water, and further details can be obtained from Professor Felicity Roddick.

Current technologies require significant input to remove nitrogen and phosphorus from wastewater to low concentrations. Algae-based wastewater treatment has emerged as an attractive option that can remove both nutrients, as well as micropollutants, simultaneously while adding value to the treatment process through resource recovery. The utilised algae can then be used for various purposes such as biofuel production, application to crops, or digested to produce biogas to offset any energy used during nutrient removal.

As immobilising the algal cells can enable intensification of the wastewater treatment process resulting in high treatment rates, it can overcome shortcomings that have limited the application of current suspended algal systems of long treatment times and difficult biomass harvesting. Where immobilised cells cannot be used, we have shown that a grafted starch flocculant, a potentially greener and lower-cost alternative, was more effective than traditional flocculants for harvesting suspended microalgae.

Centre researchers have demonstrated that not only can alginate-immobilised and suspended microalgae successfully treat municipal wastewater with a wide range of characteristics, but also treat the reverse osmosis concentrate (ROC) resulting from the advanced treatment of municipal wastewater. Appropriate selection of species enabled continuous treatment of wastewater with alginate-immobilised cells to produce effluent which complied with appropriate water quality standards. The same species also proved best for treating the ROC. It was demonstrated that the resultant immobilised and free cell algal biomass could produce significant amounts of energy via anaerobic digestion without the need for pre-treatment, and that the high salinity and nutrient concentrations in the ROC could significantly improve methane production.

Macroalgae and microalgal consortia are currently being investigated for municipal ROC treatment. This work was supported by South East Water, Water Research Australia and Goulburn Valley Water. Further details can be obtained from Associate Professor Linhua Fan.

Assessing contamination impacts on groundwater resources to meet ongoing regulatory requirements can be difficult. In the urban environment, anthropogenic activities provide numerous potential sources of contamination which can often lead to difficulties in identifying the processes impacting groundwater quality (natural and anthropogenic). This is particularly relevant at Wastewater Treatment Plants (WWTPs) that are often subject to changes in land use and composition of contaminant sources over time and space, as well as multiple potential hydrogeochemical interactions. WWTPs are also often located in environments with multiple potential contamination sources. Conventional monitoring methods are often unable to distinguish between site and off-site-derived contamination impacts, leading to uncertainties when determining compliance with site licence conditions.

This project developed a range of novel groundwater tracers – specifically radioactive isotopes, stable isotopes and Contaminants of Emerging Concern (CECs) to help address this challenge. These tracers, when used in conjunction with routine monitoring methods, have shown great potential in better characterising wastewater derived impacts on underlying groundwater systems and distinguishing them from other sources in the catchment, such as agriculture. This provides greater insight and certainty in the assessment of impacts to groundwater, and a potential means of enhancing ongoing monitoring, management and/or remedial works. The work has helped equip site operators and their consultants with useful tools to manage the Impact of groundwater contamination and ensure remediation efforts are useful and productive. The work also won the 2020 Australasian Land and Groundwater Association Annual Industry Excellence Award for the Innovation that has most advanced the practise of contaminated land assessment.

A team led by Professor Veeriah Jegatheesan has conducted extensive theoretical and experimental research on membrane bioreactors (MBRs) to treat agricultural runoff, effluents from aquaculture, textile mills, carwash stations, abattoirs, house boats and chemical industries as well as landfill leachates.

Various configurations of MBRs and their optimum conditions for different wastewaters have been established. Biological processes and membrane separation have been modelled using AQUASIM and validated for several types of wastewaters through the data obtained from in-house experiments and the literature. Applications of MBRs with other membrane processes to provide multi-barrier systems to various pollutants are of great interest to this team. So far, the team has published 39 articles on various aspects of MBR use.

Current research includes collaborative investigation with national and international partners on the impacts of micro- and nanoplastics on the performance of membrane bioreactors.

A team led by Professor Veeriah Jegatheesan is conducting extensive research on recovering salts and increasing the water recovery from the concentrate generated by seawater reverse osmosis (SWRO) plants.

Membrane Distillation Crystallization (MCD) is being researched for this purpose. In order to produce crystals with high purity, novel nanofiltration (NF) membranes are being synthesized to use as pre-treatment to the SWRO process. Various aspects of NF are being modelled to assist the synthesis. Modelling of the performance of MCD is being carried out to optimize crystal formation.

Wastewater treatment plants (WWTPs) are the major receivers of microplastics (MPs) prior to their release into open waterways. The major proportion of MPs are generated from textile fibres from washing machines and plastic commodities such as personal care products and cosmetics, these particles enter WWTPs through municipal wastewater discharge systems. Current studies focus on the removal of MPs (1 µm to 5 mm in size) in primary and secondary wastewater treatment processes. Studies have demonstrated that these processes do not remove all MPs and that well over 100 million MP particles are released from WWTPs each day.

Of concern, our preliminary data shows that the levels of nanoplastics (NPs) released into the environment after wastewater treatment due to water shear forces are at least 40 times greater than the levels of MPs. Notably, NPs have potentially greater health impacts due to their greater surface area, enabling them to adsorb heavy metals and other toxic species, that are then consumed by humans, animals, and aquatic organisms. WETT researchers are working on solving this problem by (i) developing/modifying the existing technology used in the primary treatment stage to remove NPs/MPs from wastewater so that these pollutants do not enter the next stages of the WWTP process, and (ii) developing a membrane-based platform for tertiary treatment to remove NPs/MPs with other impurities present in secondary effluent.

Further details can be obtained from Dr Biplob Pramanik.

Road dust-associated microplastics (MPs) carried by runoff are major sources of MP pollution in the marine environment. The major contributors of MPs in road dust are direct wear and degradation of vehicle tyres, road marking paints including thermoplastics and elastomers, as well as polymer-modified bitumen used for road pavement and crushed plastics along the road kerb.

We found that the major road dust-associated MP polymers are polyethylene (LDPE/HDPE), polypropylene and polyamide. It is expected that these MPs could be washed off with road dust during rainfall events and carried by stormwater into the open water environment. WETT researchers are currently looking at the fate of road dust-associated MPs in stormwater as well as developing a technological platform to control these pollutants before they reach open water environments.

Further details are available from Dr Biplob Pramanik.

Humanitarian Engineering explores the role and application of engineering to disadvantaged, marginalised and vulnerable communities to improve quality of life.

In 2015 it was estimated that almost a third of the global population lacked access to improved sanitation facilities with almost a billion people resorting to open defecation. Additionally, around 10% of the global population lacked access to an improved source of drinking water. Whilst mandated by the Universal Declaration of Human rights over 70 years ago millions of people, particularly in less developed nations, still suffer the adverse health effects of a lack of access to these essential services.

The global Sustainable Development Goals (SDGs) provides the framework with which to achieve universal access to Water, Sanitation and Hygiene (WaSH) services by 2030. Whilst huge progress is being made, spurred on by support from philanthropy such as the Gates Foundation the biggest gains are being seen in urban environments or where installing engineered infrastructure is relatively simple.

In this project researchers are exploring the use of interdisciplinary methods such as anthropology, economics, and politics to examine the household level factors affecting use of WaSH services. Using a discovery-based methodology including interviews, participatory observation and systems thinking, the teams are investigating current barriers to WaSH services in partnership with WaterAid Australia, Abundant Water, and Oxfam Australia.

Water quality is a critical challenge in Asia in the context of growing industrialization, urbanization, and climate change. Nature-based solutions (NBS) could play an important role in reducing urban water pollution while generating multiple co-benefits that could make cities more liveable and resilient. In this regard, several pilot and demonstration projects have been set up to explore their potential across cities in Asia. Their effectiveness, however, has not been adequately documented and how they can be sustained, replicated, and up-scaled remains poorly understood.

A project led by Professor Veeriah Jegatheesan of the WETT Centre with multiple international partners, funded by the Asia-Pacific Network for Global Change Research, is contributing to addressing those questions. The researchers are compiling and analyzing the experiences of existing pilot and full-scale as well as demonstration projects on floating wetlands, constructed wetlands and a maturation pond in six cities in Southeast Asia (two in each Sri Lanka, Philippines and Vietnam).

Using this information they are developing and testing a nature-based water treatment pathways methodology and guide that can be used to support the establishment, maintenance and scaling of nature-based water treatment through collaborative action research and multi-stakeholder consultations. The project is being implemented in close collaboration with relevant international networks and is informed by international experiences with the integration of nature-based water treatment in urban water management and planning from Australia and Europe.