Quantifying pathogen log reduction in Australian activated sludge plants

This work describes the prediction of pathogen reduction performance of Australian activated sludge plants (ASPs) and enables the effect of 'upset' plant conditions on pathogen reduction to be integrated into treatment plant management plans and critical control points (CCPs). The project outcomes assist with the implementation of Australian national and state water recycling guidelines, and aim to minimise the costs associated with validation and management of recycled water plants. This will inform regulators as to the scientifically warranted log reduction value (LRV) of protozoa, viruses and bacteria that can be attributed to ASPs. This paper reports on two major project tasks: a literature review on pathogen and indicator reduction by ASPs; and collation and analysis of Australian ASP data sets that report pathogen and indicator reduction. It was found that a pathogen log 10 reduction value of 1.0 to 3.0 can be attributed to the activated sludge process. Further Pilot Plant work investigating the effect of sludge age on LRV will be presented at Ozwater 2010.