Impact of improved recycled water quality on a Sydney irrigation scheme

Treated effluent has been used for irrigation, including for some food crops, by the Hawkesbury Water Recycling Scheme at the University of Western Sydney, Hawkesbury Campus, for some years. In recent years the STP concerned was upgraded from trickling filter to IDAL. The impact of improved effluent was compared with previous observations, in all, over a four year period. Monitoring of water quality in on-site storages suggested that recycled water impoundments should be regarded not merely as storage buffers but as a continuation of the treatment train in which improvement or deterioration of water quality can occur with time, under the action of physical, chemical and biological factors and is an important area requiring further research. End-user interests also need to be studied with agriculturalists preferring high nutrient irrigation water and environmental and health managers preferring low nutrient levels.