Institute for Sustainability

Energy neutral treatment of municipal wastewater

Towards Energy Neutral Treatment of Municipal Wastewater

Principal Investigator and presenter at Institute for Sustainability Conference: Dr. Jan Dolfing, School of Civil Engineering and Geosciences

Summary

In the UK about 3% of all electricity generated is used by the water industry, about half of that for the aeration of wastewater. Thus, the current aerobic wastewater treatment technology is very energy intensive and not sustainable. In tropical countries like Brazil anaerobic (pre-) treatment of municipal wastewater is already an established technology, essentially circumventing the need for aeration. In Western-Europe this is still a holy grail. Temperature is the bottleneck.

Attempts to adapt sludge (that is 'the microorganisms that are doing the job') from mesophilic reactors to low temperatures (4, 8, or 15 oC) have met only limited success.

We therefore asked the question whether start-up of anaerobic treatment systems inoculated with cold-adapted microorganisms would bring low temperature anaerobic wastewater treatment within reach.  To begin to answer this question we went to the Arctic and other permanent low temperature environments to collect microorganisms from various soils and sediments, and used this material to seed a series of batch reactors operated with raw municipal wastewater at 4, 8, and 15 oC.

After a lengthy adaptation period the inocula now show robust wastewater based methanogenesis. The next challenges are to further enrich and characterize this biomass and to explore and potentially demonstrate the feasibility of the treatment of municipal wastewater at ambient UK temperatures with these and similar seed materials. Funding from the Institute for Sustainability allows us to move forward in this direction.