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Pathogen removal in activated sludge

April 1, 2010

Understanding the log reduction potential of individual elements in waste water treatment trains is typically poor...

Project 2001 - Quantification of pathogen removal in activated sludge treatment (Water Futures)

A comprehensive understanding of pathogen reduction across the treatment train is required to understand the pathogen reduction risk of various treatment trains. Unfortunately, understanding the log reduction potential of individual elements in the treatment train is typically poor. Consequently, log reduction credits attributable to treatment systems may be far more conservative than the actual system performance. This project is providing information on pathogen removal performance through an activated sludge plant (ASP), including an assessment of the performance during "upset" plant conditions. To achieve this, a pilot plant facility has been established at the Eastern Treatment Plant in Melbourne, Victoria.


The project consists of two tasks: (i) a literature review on pathogen and indicator reduction by activated sludge plants, including an additional report to collate and analyse Australian data sets for pathogen and indicator removal by ASPs; and (ii) using a pilot scale ASP to determine the usefulness of indicators for Cryptosporidium reduction by ASP. The literature review has recently been updated and will be available soon. Key recommendations from the literature review were factored into the experimental plan. The first phase of the experimental work at the pilot plant has been completed, and the final report is currently being prepared.


The range of log reduction values collected from the literature and the experimental program were remarkably consistent. For the 3 major pathogen groups (i.e. viruses, bacteria and protozoans) the log reduction value ranges were 1.0-2.9, 1-2.8 and 0.5 – 2.3 log10, respectively. This project was predominantly funded by the Victorian Smart Water Fund (SWF), and the project team has recently secured additional SWF funding to continue the pilot plant work at Eastern Treatment Plant during 2010.