Water and the Circular Economy
Project Round
Project Number
Research Organisation
Food Science Australia

Sludge Digestion Enhancement

The Challenge

The Melbourne water companies are focusing on ways to reduce the stock pile for landfill and generate renewable energy efficiently by technology advancement. One option is to use anaerobic digestion to stabilize the sludge, generate renewable fuel, reduce its volatile organic content, reduce stock pile for landfill and achieve a level of disinfection. The purpose of this project was to examine the use of ultrasonic treatment of waste activated sludge to enhance the anaerobic digestion process.

The Project

An extensive literature review indicated that sonication has the potential to disintegrate and disperse organic matter structure which enhances the anaerobic digestion process both by increasing the rate of digestion and increasing the final stabilisation of sludge. The technical feasibility of using ultrasonic technology to improve anaerobic digestion of sludge by breaking up activated and primary sludge cells was also investigated.

The Outcome

The application of ultrasonic batch and continuous treatments to the thickened waste activated sludge demonstrated that its breakdown did result in more organic material becoming available for anaerobic digestion and the production of biogas. This application increased biogas yield by 10 per cent over non-sonicated control sludge.

This project successfully demonstrated that the application of ultrasonics to thickened waste activated sludge is a suitable method to make organic compounds more bio-available during anaerobic digestion resulting in the increased production of biogas.