Volcanic rock filters in decentralised wastewater treatment

Water scarcity has increased the use and acceptance of recycled water in the Australian community. The high cost of transporting recycled water is one of the last major inhibiting factors to the more widespread usage of treated effluent. The use of decentralised wastewater treatment systems which are constructed in-situ eliminates the need for recycled water to be transported from off-site locations. A decentralised treatment system allows for the wastewater produced at a location to be treated and recycled within the site. The most common purpose for recycled water is as irrigation water. Recycled water applied to soil as irrigation water may have long term sustainability issues in regards to salinity and sodicity concentrations. Traditional desalination techniques, such as reverse osmosis membranes, are capital and operationally expensive, which may make them economically unsustainable to produce irrigation water. This project examines the use of volcanic rock filter media, such as zeolite and scoria, which can reduce salinity and sodicity concentrations via cation exchange processes. The volcanic rock filter media have been trialed with wastewater from eco-villages, special events venues, and coal seam gas mines.