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Emerging paradigms in the reuse of domestic wastewater

Priest, Gregory M (2002) Emerging paradigms in the reuse of domestic wastewater. Masters by Research thesis, Murdoch University.

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Water is a key yet limited resource in Australia. With the threat of water shortages in Western Australia becoming increasingly important, there is a great need to develop strategies to sustainably manage this resource.
Conventional methods of addressing water shortages include the development of new supplies and use of expensive engineering processes. Alternative sustainable options are available from a demand side, including implementing water saving technologies and wastewater management.

The approach to water supply and disposal in developed nations is generally governed by a centralised strategy. This process often results in water being used at an unsustainable rate and disposed of in a wasteful manner. Traditional disposal methods combine all domestic wastewater for treatment and disposal. This is often an expensive undertaking, not only financially but also in terms of energy consumption and environmental impacts. The act of disposing of treated wastewaters to the environment prevents the reuse of the constituents of wastewater.

The reuse of domestic wastewater provides an opportunity to aid water conservation. Reuse of both “blackwater” (toilet wastewater) and “greywater” (wastewater from laundry, bath/shower and kitchen) has successfully been implemented in Australia and become accepted methods of water and nutrient reuse. In the last decade, another option to recycle wastewater has become popular in Europe. This is the separation and reuse of urine. Benefits obtained from these processes include water conservation and nutrient recycling, but also reduced energy consumption and protection of effluent receiving waters.

Domestic greywater has great potential for reuse in Western Australia. Regulations have recently been relaxed to enable greywater to be reused, after on-site treatment, on domestic gardens. Greywater is the largest in-house wastewater stream, therefore large volumes are available for garden irrigation. The demonstrated success of domestic greywater reuse provides the impetus to promote and implement other forms of domestic wastewater reuse. Similar to greywater reuse, the reuse of blackwater has been successfully demonstrated in Australia, most commonly on a medium-large scale (e.g. community level), but also at the individual domestic scale. Domestic blackwater reuse only awaits approval from the regulatory authorities to make it possible.

Although urine constitutes only 1% of the total domestic wastewater stream it contributes up to 80% of Nitrogen and 60% of Phosphorus found in the stream. Separating the urine either at the toilet, or immediately after flushing, enables the urine to be reused via agricultural or horticultural irrigation. Due to the high concentrations of nutrients, urine can be an effective plant fertiliser, approximately equal to that of a chemical fertiliser. The challenge is to integrate these technologies and practices to provide a method of total domestic wastewater management and reuse.

In order to implement domestic wastewater reuse the State Government and the Regulating Authorities must shift from focussing on conventional water conservation measures to examining the emerging paradigms.

Item Type: Thesis (Masters by Research)
Murdoch Affiliation(s): School of Environmental Science
Supervisor(s): Ho, Goen
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