FENNER CONFERENCE ON THE ENVIRONMENT
Innovation in urban water management: Advancing technologies and their implications
Dr Tom Hatton
Tom Hatton is Director of CSIRO's Water for a Healthy Country Flagship Research Program, leading a team of more than 400 research scientists and technical staff addressing Australia’s priority water research needs, including water system optimisation, improved treatment and recycling technologies, more effective environmental water allocation, enhanced monitoring and forecasting, and security of supply. Their goal is to dramatically increase the economic, social and environmental benefits of water for Australia.
Tom has 25 years of research experience in a broad range of land and water related disciplines including ecology, bushfire science, ecohydrology, water allocation, salinity and catchment hydrology.
An overview of anticipated technical advances in water monitoring, treatment and management is provided, with particular emphasis on the urban context, in conjunction with the forecast gap in supply versus demand in our major cities. Water is becoming a scarce and vigorously contested resource. Our water trading markets, regulatory systems and investment strategies for new water infrastructure and environmental management all demand greatly improved information on the state and future of our water resources. The key to improving the management of our nation’s scarce water resources is knowing how much water we have now and expect to have in the future, who is entitled to use it and under what conditions, and how it is actually being used, traded and/or modified in real time. Australia can expect disruptive, revolutionising water data acquisition, reporting and forecasting to emerge over the next decade as water systems are increasingly sensorised, with water data telemetered, delivered through web-based, near-real time reporting and complemented with hydrological model-data fusions that provide greatly enhanced and timely flood, condition and supply forecasts. The value that these water information systems offer in underpinning demand management, water trading and supply forecasting is highlighted.
Australia can also expect significant advances in technologies that produce fit-for-purpose water (particularly potable water) from poor quality feedstock (eg, seawater, saline groundwater, wastewater). Membrane processes are used widely in the water industry and are capable of producing consistently high quality water. However, the performance of the membrane decreases with time due to fouling and biological growth on its surface; and the process is still energy intensive due to the high driving pressure. The problems have been known for some time and there is considerable research going on in these areas.
New membrane technologies feature the use of low pressure systems that reduce the overall operating cost of the process. New membrane materials are actively being searched, with many researchers moving away from traditional organic (plastic membranes) to investigate hybrid membranes (inorganic matrix with inorganic particles embedded in the material) or nano-structured organic or inorganic materials (eg, carbon nanotubes). The hybrid materials offer the potential advantage of being able to tailor the pore chemistry independently of the pore size and structure. This approach appears to be successful for gas separation membranes and research into water-based separation processes using hybrid membranes is in its early stages.
Membrane fouling arising from organic matter and biological growth has been actively investigated and recent researches have indicated the possible elimination by correctly matching the pre-treatment and the membrane type. There is also considerable scope to improve technologies such as electrodialysis, capacitive adsorption, forward osmosis and membrane distillation.
These advances in water treatment membrane efficiency and operating environments will drive down the costs of new urban water supplies from non-traditional sources that are largely independent of the vagaries of climate, and with relatively less environmental impact than pulling more fresh water out of terrestrial environments. This will accelerate the incorporation of water recycling and desalination as part of metropolitan water supply schemes and lead to more robust supply systems (‘security through diversity’).
A set of technologies of great potential significance to water resource management and new supply is embodied in the capture, storage and reuse of low quality water by storing it underground. Managed Aquifer Recharge (MAR) involves the enhanced recharge of water to aquifers under managed conditions. MAR is being used globally for the capture and storage of water sources but has been given little credit for improving the quality of the recharged water. Recent research is demonstrating that MAR can be used to significantly improve the quality of the recharged water due to biological, chemical and physical processes within the aquifer. This is in addition to a cost-effective alternative to storing water in times of surplus to demand.
Research is showing that if recharged water is kept in the aquifer for an appropriate residence time then contaminants, including nutrients, microbial pathogens and trace organics such as hormones, can be stripped from the recharged water. This capacity to improve water quality has the potential for MAR to be used not only for water capture and storage, but also as a treatment barrier that can be employed as part of water reuse schemes. This treatment capability also has the potential to improve the risk management of water reuse schemes by acting as a storage buffer and control point to protect against failure of conventional treatment processes; decrease treatment and operational costs; and increase public confidence and acceptance of water recycling. MAR may even have the potential to be used as an active part of treatment processes to produce high quality recycled water by combining with engineered treatment systems such as reverse osmosis membranes, thus reducing costs while increasing treatment reliability.
