West Camden STP Advanced System Design Achieves Total Phosphorus less than 0.04 mg/L

The West Camden Sewage Treatment Plant, located in New South Wales, Australia, required upgrading for both increased capacity and to achieve new stricter nitrogen and phosphorus limits. The plant capacity was increased from 10 ML/day (2.6 MGD) to 23 ML/d (6.0 MGD) on an average day basis. Additionally, full nutrient removal was implemented with a target effluent TN value of 7.5 mg/L (median) and a target effluent total phosphorus of 0.04 mg/L (median). The West Camden STP was commissioned and placed into service in October 2009.The ability of full scale wastewater treatment systems to reliably achieve very low phosphorus limits has been proven in the design and operation of the West Camden STP. The system uses a combination of biological phosphorus removal with multipoint chemical addition and metal salt recycle to achieve these goals at the lowest feasible chemical dosage. Data indicates that that the metal salt usage is approximately half that would normally be expected for these effluent goals. A key innovation in this design was the recycle of tertiary metal salts sludge to the head of the plant to promote further absorption of phosphorus by the tertiary sludge in the secondary system in combination with the high shear alum addition system.Full scale operation of the West Camden STP has shown that design and operation of facilities to achieve very low phosphorus is feasible at low chemical usage rates.