Recycled Water for Heavy Industry and to Prevent Seawater Intrusion

Economic Value and Assessment

Technology and Treatment

Guidelines and Validation

Heavy industry can have high water demands for processing, cooling and site maintenance. Many industries in Western Australia rely on groundwater. Using recycled water to recharge aquifers (managed aquifer recharge—MAR) which have falling levels and increasing seawater intrusion is seen as a viable option. Existing wastewater treatment facilities on the Western Trade Coast could supply more than 50 gigalitres of water for MAR, which industries could then extract using their existing borefields.

This project evaluated recharge schemes from a hydrological, engineering, environmental and socio-economic perspective. It compared engineering treatment systems, and assessed the costs, benefits, risks and opportunities to deliver recycled water to industry, while improving environmental values to groundwater-supported wetlands. The demonstration of MAR in the Cockburn Sound catchment opened up the likelihood of adoption of MAR to replenish aquifers and to build sea water intrusion barriers around the Australian coast, where conditions permit.

WORK UNDERTAKEN AND OUTCOMES

The project found that MAR with recycled treated wastewater is a cost-effective option for augmenting non potable water supplies at Kwinana’s heavy industry precinct near Perth. The project investigated the economic and technical feasibility, and the environmental and social benefits, of recharging aquifers with recycled water at several sites in the region.

The Kwinana industrial area has advantages for evaluating MAR with recycled water. Groundwater is not used for drinking or private irrigation, and there is an opportunity to control access to infiltration ponds, which are cheaper to install and maintain than buried galleries or injection bores.The project shows that recycled water infiltration ponds are cost effective as the Kwinana industry’s current main source of non-potable water (shallow groundwater) becomes less secure and industrial demand continues to grow. The analysis describes options and assumptions about the cost of alternatives, the cost of tapping into the Sepia Depression Ocean Outfall Line (SDOOL), the need and cost of pre-treating the water, and managing down-stream discharge.

The cost of MAR water ranges between $0.40 and 1.94/kL, with the lower costs being for no pre-treatment and infiltration by ponds close to the outlet line. Pumping distance and the need to remove nitrogen increase costs the most. The proportion of MAR water that can be recovered by industry also affects its cost effectiveness, as some may be required for environmental purposes in the drying climate. When compared to the price of purchasing recycled water or the price of scheme water, the cost of MAR water is more competitive. This finding is reinforced by results from another independent Centre-funded MAR project the economic benefit of MAR with recycled water.

The project concluded discharging treated wastewater to the Superficial Aquifer at the Kwinana Waste Water Treatment Plant appears to have helped save The Spectacles wetlands from drying out. It also found no long-term evidence that recycled water has contaminated the wetlands or the groundwater, which discharges into Cockburn Sound.

ADOPTION AND IMPACT

The project findings were included in demand planning for the Kwinana Industrial area in Western Australia and the project outcomes have contributed to recognition that state-wide application of managed aquifer recharge along the western coast of Australia is a feasible option where there are problems associated with groundwater level decline, loss of wetlands, and seawater intrusion. Commonwealth funding to further the research, supported by the CSIRO (project leader), Kwinana Industrial Council, and the Department of Water, has been approved.

Demonstrating that managed aquifer recharge can successfully manage water for both nature and heavy industry at Cockburn Sound could see wider adoption of MAR around Australia.

PROJECT PARTNERS
Lead organisation:	CSIRO Land and Water Flagship
Partner organisations:	Kwinana Industry Council
	WA Water Corporation
	WA Land Authority
	WA Department of Health
	WA Department of Water

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