Due to its potential of chemical energy (organic content), municipal wastewater is yet a largely untapped source of renewable energy. Instead, wastewater treatment plants (WWTPs) require primary energy, mostly as aeration requirements, to clean and dispose municipal effluents. The large WWTPs of Berlin have currently a specific energy demand of about 0.2-0.4 kWh/m3, but the complete methanisation of the organic content present in the wastewater could theoretically generate up to 0.8 kWh/m3 with state-of-the-art technologies.

The project CARISMO is based on the vision and paradigm shift that by 2030, the WWTPs will become net producer of renewable energy instead of net consumer of fossil energy. The project is thought to set bases towards this goal, to identify and assess potential treatment schemes and to define technical bottlenecks and limitations.

Three new treatment schemes, all of them based on the low energy microsieve separation process, will be evaluated at pilot scale with real wastewater. The results of the pilot study will be used to perform a feasibility study of the concepts with mass flow models and to provide recommendations with regards to the full treatment schemes including post-treatment for nutrients removal.

German sustainability Award 2014 – CARISMO project nominated for the category Research