In the face of growing demand for water and declining rainfall, the industrial use of recycled wastewater in Western Australia is likely to increase. The improper treatment and use of recycled water can, however, pose real health and environmental risks, and as a result, the treatment and use of recycled water in WA is subject to an array of regulatory controls, under both the Health Act 1911 (WA) and the Environmental Protection Act 1986 (WA)("EP Act").
Section 98 of the Health Act requires that before sewage can be deposited or put down on any place authorisation must be granted by the Department of Health ("DOH"). Under section 107 of the Health Act, construction or use of an apparatus for the treatment of sewage must also be authorised by the DOH where the treatment involves more than one dwelling or produces more than 540 litres of sewage per day. Sewage is defined very broadly by section 3 of the Health Act to include "any waste composed wholly or in part of liquid". Consequently, any scheme to collect and treat wastewater must be authorised by the DOH and may be subject to a variety of conditions including conditions specifying the level of treatment required and permitted uses of the water produced.
Under the EP Act, parties wishing to construct or operate a water recycling facility must obtain various approvals from the Department of Environment and Conservation ("DEC"). The types of approval required depends upon the capacity of the facility. Any organisation seeking to construct a facility capable of treating over 20 cubic metres of water per day is required to obtain a works approval from the Department of Environment and Conservation ("DEC") prior to construction. The purpose of the works approval is to ensure the treatment system is appropriately designed and constructed and that the environmental performance of the proposed facility will be acceptable.
Where the treatment facility has a capacity to produce more than 20 cubic metres of water per day, but less than 100 cubic metres a day, the premises is designated a category 85 sewage facility under the EP Act and a registration is required to operate. No conditions are imposed under a registration as it is assumend that the smaller volume of recycled water is unlikely to pose a significant environmental risk.
If the treatment facility has the capacity to process over 100 cubic metres of water per day an EP Act licence is required to operate. This is issued by the DEC and will contain conditions which are aimed at preventing or minimising the potential for pollution and often includes requirements for ongoing monitoring and assessment of environmental impacts.
Mandatory levels of treatment
The DOH requires differing levels of treatment for recycled water, depending upon the health risks associated with the water's intended use. The Western Australian Government has developed the Guidelines for the Use of Recycled Water in Western Australia (2007), which are intended to be consistent with the National Guidelines for Water Recycling drafted by the National Resource Management Ministerial Council and the Environment Protection and Heritage Council.
If the recycled water is to be used in an "open system", where there is a potential for employees or members of the public to be exposed to the water (such as for dust suppression or wash down water), then the Guidelines indicate that "Class A" recycled water must be used. Class A recycled water is water that has been put through three processes: secondary treatment (for example activated sludge processes or stabilization ponds), filtration (through soil, filter media or membrane processes) and disinfection (destruction or removal of pathogens by chemical, physical or biological means).
If the recycled water is to be used in a "closed system" (such as cooling water), where there is very little risk of exposure to workers or the public, then the Guidelines indicate that "Class C" recycled water may be used. Class C water is water that has been through secondary treatment and pathogen reduction (for example detention in a pondage system for 30 days or sand or membrane filtration).
The Guidelines also indicate that users who obtain recycled water from off site should enter into an Agreement of Supply with the supplier of that water containing a description of the characteristics of the recycled water (source, quality and quantity) and a description of any restrictions on use of the water.
Employers should also be aware that the Occupational Health and Safety Act 1984 places an obligation on employers to ensure that employees are not exposed to hazards arising from the use of recycled water.
While the recycling of water can be an efficient and sustainable way of meeting the water requirements of industry, it is essential for potential producers and users of recycled water to be familiar with the additional regulatory requirements and risk management processes that are involved in safely using this substantial and increasingly important resource.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.