A/Professor David McCarthy

A/Professor David McCarthy

Associate Professor in Water Engineering
Department of Civil Engineering
Room 120, 23 College Walk (B60), Clayton Campus

Clean-up provides stormwater as alternative supply

Helping Melbourne keep its urban river and water systems healthy is the underlying objective of Dr David McCarthy’s research at the internationally renowned Monash University Centre for Water Sensitive Cities. At the top of his agenda is the need to tackle pollution to make sure stormwater is safe for reuse and discharge to downstream recreational water bodies.

Population growth and climate change are both expected to place pressure on existing water supplies. Stormwater provides an alternative source of supply, provided it can be effectively treated to remove pollutants.

David’s research is rising to this challenge. He has two project areas. One is identifying the pollutants that accumulate in stormwater. The other is improving stormwater harvesting and reuse by developing sustainable, low-cost, low-energy treatment systems to remove those pollutants. He is seeking simple, sustainable solutions that reduce our environmental impact.

Stormwater is not just rainwater, David says. Rainwater is relatively uncontaminated when it is harvested. But stormwater collects any number of exotic pollutants as it rushes across roads and footpaths. Leaking septic tanks and misaligned domestic and trade sewers add to the contamination.

He says many of the systems being installed to treat stormwater for reuse are highly engineered, energy-hungry and expensive to build and operate. These kinds of systems are difficult to sustain in the long term.

Treatment is usually based on ‘indicator’ organisms. However, stormwater can contain a whole host of more exotic disease-causing organisms, some of which are potentially deadly. ‘If we’re going to reuse this water we need to better understand the risks and eliminate the actual contaminants, not just indicator organisms. And it is as important for the rivers and creeks, where much of the stormwater ends up, as it is for potential urban reuse.’

One of the simplest stormwater treatment approaches is biofiltration. Stormwater is collected and processed through a ‘vegetated filter’. This could be something like a swale that has been planted with shrubs. The plants help to take up nutrients and other specific pollutants from the stormwater. The sand or soil media lining the swale removes pollutants in several different ways. It can physically strain out pollutants, absorb them, or transform them into something less harmful through various chemical or biological processes. The treated water can then be redirected for discharge to downstream water bodies or for reuse.

David says biofiltration treatment of common stormwater pollutants is well recognised. Less well understood is how these systems perform in removing some of the more exotic pollutants. Improving this understanding is essential if stormwater is to be reused – whether that is for backyards, public parks or toilets.

He says there is potential to develop stormwater harvesting systems for use at the individual property level – on gardens and for flushing toilets. Rainwater harvesting is already common practice at the household level. Adding stormwater collected from other surfaces would simply be an extension of this.

At a street level, stormwater could be used for trees and nature strips. At a precinct level, there could be more widespread watering of community parks and gardens and stormwater could even be introduced into the household for non-drinking uses.

Not surprisingly, David’s research has drawn cooperation from a wide range of water agencies in Melbourne and industry partners. He collaborates with leading national and international universities in much of his research. He enjoys the sense of being part of a much larger effort to better understand Australia’s aquatic systems, especially those in urbanised areas.

Research Projects

Current projects

ABC Waters Evaluation and Modelling: Punggol New Town - C39 Precinct

Power Efficient Waste Water Treatment using Graphene Oxide Technology

Fresh water is a scarce commodity. Wastewater is a potential source of fresh water however treatment is energy intensive. Graphene oxide based water treatment technologies have potential to significantly reduce energy requirements. Modified graphene oxide adsorbents and membranes will be used to clean water and recover valuable organics. The CRC support will provide the scientific basis for the materials chemistry and production processes.

BUOY for public notification of recreational water quality

This project will develop a semi-real-time monitoring platform (a buoy) for public notification of recreational water quality. The buoy will analyse the water quality in-situ for microbial concentrations. A “smart material” with colour switching ability is coated on the surface, which turns red when water quality is poor to inform the community not to swim. The system will be self-powered (solar cells) and automatic.

Beach Guard -Tanti creek SEW

Beach Guard-Tanti Creek Study South East Water-
Faercal contamination of waterways from stormwater has serious implications for the health of recreational users and ecosystem services in the receiving environment. This project will investigate the most effective detection methods to identify faecal pollution in waterways

Development of Solar-induced, Dark-active Photocatalytic Membranes for Water Disinfection

Stormwater is one of the last freshwater resources that has not been utilized to its full potential. However, large amount of faecal pathogens in stormwater limit its harvesting practive. This project aims at addressing this significant problem by developing the next generation of photocatalytic membranes for stormwater disinfection. The proposed membranes not only are passive water treatment technology which only utilizes solar energy, but also are operated regardless of weather, even at night. The results will provide new insights on development of future water treatment technologies. This project will also raise Australia’s credibility and competitiveness in the water and membrane industries.

Advancing water pollution emissions modelling in cities of the future

This project aims to advance stormwater pollution modelling and enhance its link with urban development. Current management of stormwater pollution by industry often results in inadequate strategies and, most crucially, suboptimal financial investments. This is unlikely to improve in light of future urban growth and climate change. As such, there is urgency in addressing decade-old pollution modelling knowledge gaps and the lack of a multidisciplinary approach to stormwater pollution management. The anticipated goal is a new modelling tool to be used by industry to explore scenarios on how stormwater pollution in changing cities can be effectively managed through smarter and economically efficient technological and policy solutions.

Safe to swim with the bugs? From hazard identification to risk management

Health risks to recreational users of urban rivers from water- and sediment-borne bacteria will be explored via (1) the development of a suite of novel molecular microbiological and in-vitro assays and (2) microbial risk
assessment modelling. Furthermore, this project aims to deliver novel source tracking methods to help our partners mitigate and manage these risks. This is an important research area since the number of bacterialrelated
water-borne outbreaks associated with recreational activities is rising, yet increased pressure is being placed on our waterway managers to re-open these rivers for recreation. The project strives to benefit urban
communities via ensuring our waterway managers make informed decisions about river recreation.

Interactions between plants and faecal pathogens in urban water treatment: significance of soil microbes, plant debris, root exudates and rhizosphere

It is important to treat pathogens in stormwater and wastewater before release into downstream recreational waters or harvesting/reuse. Using plants in water treatment improves the removal of pollutants of concern to human and ecosystem health. However, the exact mechanisms which generate this improvement remain unknown, and this is especially true for faecal pathogen removal. The aim of this project is to understand the interactive role that roots, their exudates, plant debris and soil microbes play in faecal pathogen removal in urban water treatment systems. Through this understanding, this project will lead to optimised low-energy, low-tech and low-maintenance treatment systems.

Past projects

Aquarevo-Challenge Testing SEW

Research aim is to challenge test rainwater to hot water treatment system designed the Aquavero site for South East Water, with a specific focus on the ability of the system to remove pathogenic microorganisms which may be present in roof water.

Troups Creek West Westland Rectification Project

As a part of the Troups Creek West Wetland Rectification project, Alluvium Consulting has requested further testing of the proposed functional design of the wetland by conducting numerical modelling of wetland’s hydrodynamics and sediment dynamics. The aim of the numerical modelling is to compare the wetland performance in functional design conditions with the wetland performance in the current state. The particular emphasis is on the total suspended solids (TSS)/ Turbidity level in the outlet of the wetland, as the treated water is harvested for the South East Water treatment plant for reuse within the catchment.

Integrated multi-functional urban water systems

Integration and Demonstration through Urban Design

Cities as Water Supply Catchments - Sustainable Technologies

Priority pollutants in urban water systems: using sustainable urban water infrastructure to mitigate the risks they pose to humans and the environment

Fit-for-purpose water production

Demonstrating Capability for Stormwater Harvesting in Israeli Cities

Sources, sinks and processes of faecal contamination in urban estuaries; a case study of the lower Yarra River Estuary

Urban estuaries provide important functions to the community; however, elevated pollution levels (caused by urbanisation) are limiting their benefits. Of particular concern are faecal contamination levels, increasing the risks to users. Using the Yarra Estuary as a case study, we will first monitor pathogen levels to understand these risks. We will then identify prominent sources and sinks, and explore the dynamics of both pathogens and faecal indicators within the estuary then using this knowledge to develop a hydrodynamic-microorganism model. Using the outputs of the investigation, and applying the model for hypothesis testing, the project will inform future decision making and mitigation strategies.

Vegetable raingardens - the benefits and performance

Monitoring of Sediment and Water quality in Wilsmere Billabong and the Yarra River

Sinks and Sources of Faecal Microorganisms in the Yarra River Estuary

Effective monitoring of Pollution Types and Loads entering the Drainage System

Impact of Sewer Overflows on Elster Creek

Monitoring of Monash City Councils EIBC water systems

Effective monitoring and assessment of contaminants impacting the mid to lower Yarra catchments - Temporal Scale Assessment

New Technologies for mitigating risks of stormwater reuse

CSIRO Scholarship Agreement for Externally Funded Awards - Student: Mr David McCarthy - Project: Improving WSUD Technologies to Optimise Treatment Performance and Facilitate the Reuse of Stormwater

Last modified: 12/02/2021