This project focuses on the energy optimisation of a membrane bioreactor (MBR) by investigating the opportunities to operate it in combination with an anaerobic sludge digestion. The information available in the literature will be gathered together with results from current and recently completed projects on the energy demand of large scale communal MBR. Possible gas yields will be determined with sludges from existing MBR (with and without primary clarifier) at laboratory scale in a first step. Based on this data possible energy savings will be calculated using a model wastewater treatment plant. This 12-month work will be completed with a carbon footprint analysis of the overall process (wastewater treatment, sludge treatment and sludge disposal). The result will be a planning aid in form of a decision matrix, which will consider the possible implementation of an anaerobic sludge treatment with gas utilisation under ecological and economic aspects and can be used for new construction or upgrade of MBR.
In a second 18-month work package the optimal boundary conditions to maximise the gas yield are planned on a pilot scale MBR at the semi-technical wastewater treatment plant of the environmental authority of North Rhine-Westphalia. To do so the relevant operating parameters will be varied under consideration of the membrane performance (fouling) and the nitrogen removal. With these practical experiences the decision matrix from the first work package will be refined.