Australian Centre for Water
and Environmental Biotechnology

Short-cutting nitrogen removal

Wednesday, 06 December 2017
  • Short cut nitrogen removal

Taking short cuts is normally a bad idea when conducting research, but these University of Queensland projects are demonstrating multiple benefits from this approach.

Led by Professor Zhiguo Yuan, the Advance Queensland Innovation Partnerships (AQIP) project commenced in May with the construction of a pilot plant at the Queensland Urban Utilities Innovation Centre.

Dr Shihu Hu, AWMC research fellow and the AQIP project’s chief investigator, said that their project aims to demonstrate at pilot scale the FNA-biogas technology for zero-energy sewage treatment.

“Improving energy recovery from wastewater treatment by short cutting nitrogen removal is a hot research topic,” said Dr Hu.

Free nitrous acid (FNA) has the dual effect of both increasing methane yield from sludge through increased digestibility, and selectively suppressing the growth of nitrite-oxidizing bacteria, ‘short-cutting’ the conventional nitrification/denitrification process.

Recently developed by AWMC and City of Gold Coast, this patented technology is expected to triple the bioenergy recovery from sewage compared with what is currently achievable, while reducing the process energy consumption by ten percent.

 “The bioenergy recovered is expected to completely offset the energy consumption for sewage treatment,” said Dr Hu.

“This will effectively transform wastewater treatment plants from large energy consumers to energy producers.”

If applied to half of the sewage produced in Australia, the estimated economic benefit could be $30 to $50 million per annum, with approximately 300-350 GWh of renewable energy produced every year.

This will also result in a substantial reduction in greenhouse gas emissions, in the range of 350-450 kilo-tonnes of carbon dioxide.

“This is a major step forward for water utilities in achieving greenhouse gas neutral sewage management,” said Dr Hu.

In addition, the FNA-biogas technology can be applied through minor retrofitting of existing plants, with an estimated payback time of less than one year.

Complementary to the AQIP project, runs the MERINO project – which will demonstrate novel technologies for maximising energy recovery through innovative nitrogen removal from sewage.

 Among these innovations is a new way to achieve stable partial nitritation using FNA, and a novel way to achieve complete autotrophic nitrogen removal by coupling mainstream Anammox and denitrifying anaerobic methane oxidation (DAMO).

The projects are currently working with industry partners on process design and commissioning of two, on-site pilot plants incorporating high-rate activated sludge, partial nitritation, mainstream Anammox and DAMO, and an FNA production unit.

These demonstration projects are a critical step towards full-scale implementation of the technologies, further strengthening the position of Australian water utilities as leaders in innovation, and also creating significant business opportunities through technology licensing.

AWMC acknowledges the essential, collaborative contribution of partners to the ongoing success of the projects:

  • Griffith University
  • Southern Cross University
  • City of Gold Coast
  • Melbourne Water Corporation
  • Queensland Urban Utilities
  • South Australian Water Corporation
  • WA Water Corporation
  • Wide Bay Water Corporation