Projects

As a result of our research, salinity gradient solar ponds are currently in use as a source of heat for industrial purposes as well as sustainable water desalination.

A major Smart Water Fund project determined the treatment and conditions required to provide high quality bio solids. These can be applied to land as man-made renewable organic fertilisers. The research will inform revision of current national and state guidelines for land application of bio solids.

One of our projects characterised the organic content of the treated water from the lagoon systems at Western Treatment Plant. Its impact on microfiltration and ultrafiltration by reverse osmosis was evaluated as pre-treatment to desalination.

This project examines the properties of concentrated sludge arising from increased pressure on the capacity of wastewater treatment plants.

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.

Our researchers are solving this problem by developing a model for more accurate prediction of the final rheological properties of three blended sludge types. The new model will be used to control the ratio of the feed stream to digester content with the aim of achieving the best possible mixing performance and biogas production.

Research into chemicals found in recycled water offers a promising insight into the viability of using aquifers for water storage.

Project dates

Research activity completed in November 2013. Publications prepared and submitted April 2014.

Grants and funding

This project was funded by the U.S. National Ground Water Association.

Summary

Research into chemicals found in recycled water offers a promising insight into the viability of using aquifers for water storage.

A project team comprising Dr Matthew Currell, Dr Oliver Jones and final-year engineering student, Will McCance, investigated whether harmful contaminants could still be detected in recycled water after aquifer storage and recovery.

Using recycled water is an attractive water management strategy in drought prone areas worldwide, but the lack of places to store the water is often an issue.

One solution to this problem is aquifer storage and recovery (ASR). This involves pumping highly treated wastewater into a depleted aquifer to replenish supply and then pumping this water back out when it is needed.

The team worked from the Werribee Western Treatment Plant where around half of Melbourne's sewage is processed and almost 40 billion litres of recycled water is produced each year.

ASR schemes, such as the one at Werribee, have considerable potential in urban water management because water companies don’t need to build expensive new surface reservoirs - and since the water is stored underground, there is no loss by evaporation.

The research focused on a selection of chemicals labelled by the US EPA as “contaminants of emerging concern“ (or CECs). These are chemicals in water that had previously either not been detected, or which are now being detected at levels significantly different than expected.

The term CEC refers to a diverse range of compounds including pharmaceuticals and personal care products, pesticides and food additives among others. Environmental regulators are worried about these compounds because the risk to human health and the environment is unknown and there are very few (if any) regulations regarding their presence in the environment.

After a detailed literature review and discussions with EPA Victoria, the team selected a range of CECs including five pharmaceuticals, three disinfection by-products, two industrial chemicals, two pesticides and one food additive.

Each compound was then tested thoroughly to determine recovery rates and detection limits before they undertook any sampling.

Over a four-month period samples were found to contain low traces of chemicals which included an artificial sweetener, a detergent, a pesticide and pharmaceuticals.

The team saw some differences in concentrations and presence of some of the compounds across the sampling period, which they think reflects either seasonal variability in the amount of these substances in the influent wastewater and/or differing degrees of persistence during treatment.

Much of the work on this project was undertaken by Mr McCance as part of his final year project, providing essential work experience and skills development.

Key people

Partners

We are developing a non-toxic approach to control bio fouling.

Bio fouling damages unprotected underwater structures such as boat hulls, heat exchangers and oceanographic sensors. Traditional measures to prevent bio fouling involve toxic metal-based coatings. Our researchers are developing a non-toxic approach to control bio fouling by modifying the surfaces on which sediment of organisms occurs.

The researchers have developed synthetic surfaces mimicking the micro-topographical arrangements of the exterior of organisms, such as shark skin and lotus leaves, which naturally discourage bio fouling.

Using both laboratory experiments and computational fluid dynamic (CFD) simulations, the researchers are able to test the effectiveness of patterned surfaces in discouraging organisms from attaching themselves to underwater structures. The goal is to identify which pattern is most effective in preventing bio fouling without the use of toxic coatings.

Publications

Partha Halder, Mahyar Nasabi, Francisco J. T. Lopez, Nira Jayasuriya, Satinath Bhattacharya, Margaret Deighton, Arnan Mitchel, Muhammed A. Bhuiyan, "A Novel Approach to Determine the Efficacy of Patterned Surfaces for Biofouling Control in Relation to Microfluidic Environment", Biofouling: The J. of Bioadhesion and Biofilm Research, Vol. 29, 6, 2013, pp. 697-713

Understanding the levels of water ingested while using high pressure spray devices will help to determine future water recycling guidelines.

Problem

Recycled water is an essential part of future water management strategies in Australia.

The Australian Guidelines for Water Recycling (AGWR) set regulatory targets for public health protection on the basis that, even during non--?potable uses, small quantities of water will be inadvertently ingested from exposure to sprays and aerosols.

Requirements for water treatment are calculated to reduce the risks of illness from exposure to enteric pathogens to tolerable levels. However, assumptions on the volumes of water inadvertently ingested have little evidentiary basis and are essentially expert opinions of quantities thought to be plausible.

Project

The Car Wash Study performed was designed to find out how much water people accidentally ingest when they wash a car with a high pressure spray.

The specific objective of the project was to measure inadvertent water ingestion during washing of a hard surface using a high pressure device. This activity was chosen because of relevance to water reuse in both domestic and occupational contexts, and because it involves relatively high intensity exposure likely to result in ingestion of measurable volumes of water.

The researchers added a non-toxic chemical to tap water and asked volunteers to wash a car replica, then collected their urine for the next 24 hours. By measuring the amount of chemical found in the urine, the researchers calculated how much water the subject ingested during the car washing activity. The project was performed in collaboration with Monash University and funded by Water Research Australia.

Outcome

The project generated the first empirical quantitative data on indirect water exposure. This will be included in future revisions of the AGWR, and enable better risk assessment.

Dr David Halliwell, CEO of Water Research Australia, said “This unique and innovative project means the water industry can now reliably estimate human exposure to recycled water use in high pressure spray devices. This leads to a more efficient treatment outcome, and therefore, an improved customer value proposition. This technique can be extended across many other water exposure scenarios, which may greatly improve the cost effectiveness of water treatment for some water recycling scenarios.”

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Acknowledgement of country

RMIT University acknowledges the people of the Woi wurrung and Boon wurrung language groups of the eastern Kulin Nation on whose unceded lands we conduct the business of the University. RMIT University respectfully acknowledges their Ancestors and Elders, past and present. RMIT also acknowledges the Traditional Custodians and their Ancestors of the lands and waters across Australia where we conduct our business.