The facility processes the digester gas produced in the digestion tower by bacterial decomposition of the sewage sludge into biomethane, which is fed into the Regio Energie Solothurn grid as renewable methane. In addition to a service contract going back almost a decade, ZASE has now also commissioned the Zurich-based green tech company to convert the plant to increase its output in line with future needs.
ZASE’s catchment area comprises 40 municipalities in the cantons of Solothurn and Bern. The acquisition of a major new customer has significantly increased the volume of wastewater that the WWTP processes, and with it the production of digester gas from sewage sludge. To maxim-ise the use of the energy this sludge contains, HZI is increasing the capacity of the existing bio-methane plant by installing new membrane modules, replacing the chiller and main compressor, and converting the control system.
The existing second-generation membrane modules will be completely replaced with modules of the same size of the new, highly efficient generation. Although fewer modules will be used in future, the plant’s output can be increased to around 300 Nm³/h. This will involve replacing the chiller and the main compressor with new, more efficient models and adapting the control system in line with the increase in capacity.