Biogas (mostly methane) is currently collected at two major Melbourne wastewater treatment plants and is utilised for renewable electricity generation. One of the treatment plants currently supplies around 95 per cent of its own energy use from biogas. However, a study indicates that as much as 20 per cent of the biogas generated at the plant is not captured but remains trapped in the effluent as dissolved methane or micro-bubbles. Melbourne Water believes there may also be other streams in the wastewater treatment process (e.g. digester sludges) that could also contain methane, which could be utilised for additional on-site renewable energy generation. Effectively capturing a significant amount of this lost biogas would enable the sewage treatment process to achieve net zero electricity consumption.
The objective of this project is to identify and pilot technologies which will extract methane contained within the anaerobic effluent. Once stripped, this methane can be utilised in biogas power stations to provide renewable electricity to wastewater treatment facilities. If electricity generation is not cost effective, flaring of additional methane captured will reduce the global warming potential of emissions from the treatment process.
The learnings and findings from this project are expected to be valuable to all water utilities or industrial facilities that operate anaerobic processes and recover methane. This project is taking a multi-phased approach.
- Phase 1 Literature Review of technologies to enhance methane recovery from wastewater
- Phase 2 Laboratory Scale Trials of short listed technologies
- Hold Point – business case review before proceeding
- Phase 3 Pilot field trials
- Phase 4 Cost benefit analysis and economic model