EnAB 2 - Energy-efficient exhaust air treatment 2
Mechanical biological waste treatment (MBT) represents a basic technology for the treatment of mixed municipal solid waste (MMSW). In MBT plants MMSW is stabilized before final disposal on landfills. The biodegradation is working under aerobic conditions correlated with large airflows. The produced exhaust air has to be collected and treated. To comply with the limit for exhaust air due to the 30th Ordinance of the Federal Emission control (“30. BImSchV”) the exhaust air of MBT plants is treated, caused by a lack of alternatives, by regenerative thermal oxidation units (RTO). RTO units are not designated for the exhaust air treatment of MBT plants, so for the application of RTO units additional exothermic energy is needed. This leads to the unsatisfying situation that more than half of the total specific energy consumption of the MBT plant is sourced from the RTO.Copyright: © Department of Processing and Recycling (I.A.R.)
The goal of the follow-up project “Energy-efficient Exhaust Air Treatment 2 – EnAB 2“, which is funded by the German Federal Ministry of Economics and Energy (BMWi), is to decrease the energy consumption in MBT plants significantly. Considering the results of the previous project called EnAB the goal will be achieved mainly by reducing the energy consumption in the biological treatment and in the subsequent exhaust air treatment. The exhaust air from the aerobic biological treatment delivers only short periods of high carbon loads, which are necessary for an autothermal operation of the RTO, so high amounts of exothermic energy are still needed. Thus, alternative exhaust air treatment technologies can contribute to the reduction of energy consumption in MBT plants.
The acquired results so far allow a forecast, that the energy consumption of MBT plants can be decreased by at least 25 % by using alternative exhaust air treatment units. In EnAB 2 the exhaust air of the biological treatment will be devided according to the pollution levels into different streams, which will be treated separately by different technologies. So the volumetric flow to the RTO unit will substantially be reduced. For the separate treatment of the exhaust air streams a new collecting pipe, with the capacity for the exhaust air of 15 rotting boxes, will be build. Simultaneously, a regulation algorithm for the exhaust air management in combination with automated air flaps will be developed. The industry-scale trials will take place at the MBT Großefehn in the district of Aurich, Germany.