Pasteurisation to produce recycled water

Pasteurisation - a process used worldwide to disinfect and treat milk - will soon be used to treat recycled water in a project initiated by the Australian Water Recycling Centre of Excellence (AWRCE).

The project will be a collaborative effort, led by Victoria University with support from the Australian Water Quality Centre, Melbourne Water, WJP Solutions and two US-based companies, Pasteurization Technology Group and Carollo Engineers, which previously worked on a pasteurisation pilot plant in California.

Pasteurisation involves the rapid heating and cooling of food (usually liquid) for a short period of time. Although the process has long been used within the food industry, its potential application to wastewater has only recently become feasible thanks to heat-recovery technology. The project will test the efficiency of this technology, along with the effectiveness of the pasteurisation process, compared to conventional means of water disinfection.

The technology involves a heat exchange system that can capture and re-use waste heat, “so you’re getting something for nothing,” said Victoria University Research Fellow Dr Peter Sanciolo.

“By utilising waste heat from burning biogas (a waste by-product of water treatment) or from engines generating electricity on site to run the water treatment plant, pasteurisation disinfection technology may prove cost effective compared to purchasing electricity from the grid and using conventional disinfection treatments such as membrane filtration, ultraviolet light and chlorine,” he explained.

Dr Sanciolo noted that, although pasteurisation was successful in California, the economics of the process vary from site to site, hence the need for the trial. It will also be an important demonstration for Australian regulatory authorities. 

The project will be conducted at Melbourne’s Western Treatment Plant and will treat wastewater to a standard suitable for crop irrigation, livestock drinking and industrial use.

AWRCE CEO Mark O’Donohue said, “If successful, the project will demonstrate that pasteurisation can reduce treatment costs and energy requirements and simplify the recycled water disinfection process, under rigorous conditions required by Australian Departments of Health.”

Dr Sanciolo said that following extensive lab work to determine the pathogens the team will need to monitor, the trial itself will run for one year.