Wastewater treatment is currently undergoing a shift from nutrient destruction to nutrient recovery. The University of Queensland Nutrient Recovery Team’s Accumulate-Release-Recover research accumulates nutrients from the mainline, through anaerobic digestion, and subsequent recovery by technologies such as crystallisation for phosphorous, and electrodialysis for nitrogen and potassium. This research is currently limited to bacterial (phosphorous only) and low rate algal (phosphorous and nitrogen) accumulation methods.
This project will expand the research to include phototrophic bacteria, including purple non-sulfur and green non-sulfur bacteria to accumulate organics, nitrogen, and phosphorous as an organic solid which will then be anaerobically digested for subsequent nutrient recovery.
- Screen phototrophic bacteria in batch experiments to assess their ability to accumulate soluble carbon, nitrogen, and phosphorous
- Design and implement a high-rate phototrophic continuous bioreactor in laboratory/pilot to develop reactor technology and provide biomass for testing
- Optimise operation in terms of energy consumption and nutrient recovery
- Fully characterise release potential through anaerobic batch tests
- Demonstrate release in continuous reactor
- Pilot study
The project has a detailed utilisation and outreach program, implemented within the larger CRC for Water Sensitive Cities programme. This was formulated, particularly with input from both Victorian water utilities, and from Queensland Urban Utilities (in Brisbane). A pilot plant is planned within the CRC project, and this will be used to pilot the reactor to be developed through this project. One of the very attractive characteristics of this project is that it is not only highly innovative, applying a concept that has not been previously developed, but also very applied, orientating towards reactor development, and with a reasonable prospect for success.
The value proposition relies on recovery of approximately 70% of nitrogen in wastewater (the rest is contained in the residual biosolids which could be land-applied), as well as comparative levels of recovery of phosphorous and energy. Basic sizing and feasibility analysis was using Queensland wastewater properties, but would likely be more favorable in Victorian applications, where there is generally a higher proportion of degradable material in the feed. Recoverable streams and energy savings have been estimated at approximately $11 per consumer per year (N, P, and energy), including energy savings for nitrogen removal.
“This project is situated within a larger program of works funded by the CRC for Water Sensitive Cities from whom co-funding for this project has been supplied”