Large on-site wastewater treatment and reuse systems for commercial applications

The Central Queensland University (CQU) in partnership with GBG Project Management has installed large on-site treatment and reuse for a variety of commercial operations in Queensland. Systems range in size from 30 equivalent persons (EP) to 500 EP. Installations include taverns, motels, child care centres, and schools. The effluent produced at large commercial sites is significantly different to domestic wastewater in regards to constituents and generation patterns. Standard on-site treatment technologies used at large commercial sites may need to be adjusted to ensure water quality performance. At the sites in this study treatment is obtained through the use of a combination of septic tanks, filters, disinfection technologies, and the KEWT system, a recirculating evapotranspiration trench. A variety of filter media is used, such as zeolite, scoria, charcoal, rock, and sand. The KEWT trenches contain filter media, soil, and selected plants. Effluent passing through the KEWT trenches is filtered physically and biologically, prior to being transpired by the plants. Any excess effluent can be recirculated through the trenches or diverted for water recycling.Treated effluent at the sites is available for reuse purposes, predominately irrigation. Effluent flow through the treatment and recycling systems is regulated by remotely controlled SCADA technology. The SCADA system is an intelligent control device that automatically regulates flow throughout the treatment process minimising the risk of hydraulic surges.