Off-air management and treatment in MBT plants / Abluftmanagement und Abluftbehandlung an Anlagen zur mechanisch-biologischen Abfallbehandlung

The present work deals with possibilities to comply with the standards given by the ordinance on biological waste treatment facilities (30. BImSchV). A main focus thereby was done on the environmental impact of the waste gas cleaning system called non catalytic (regenerative) thermal oxidation (RTO). As a result of the new environmental standards the conception of mechanical biological (pre-)treatment plants (MBT/P) had to change. In particular the low standards for organic carbons in the exhaust gas of MBT necessitate a thermal treatment of this gas at least for heavily loaded gas streams. As the knowledge about emissions of RTO plant used for the treatment of MBT exhaust gas was very limited, extensive measurements were made within this research work. Beside the emission standards for several pollutants the ordinance on biological waste treatment facilities gives weight specific standards (loads) for organic carbons and nitrous oxide. These loads involve the waste input quantities and the exhaust air volumes of MBT plants into the emission calculation. An emission source analysis with a special focus on the organic carbon emissions from plant components of a modern MBT plants was made at the MBT in Borken (North Rhine-Westphalia). The found emission progression in both the discharge area and the area of mechanical waste treatment gave reason to the conclusion that a cleaning of gas from these areas via biofilters as publicised by several companies will not work properly. So these gas amounts have to be used in subsequent areas of MBT such as the biological waste treatment. In the area of biological waste treatment an additional and extensive reduction of the total amount of exhaust gas from MBT plants can be achieved by a more effective usage of oxygen in the air and by a more effective energy removal. To what extent both factors can be varied without interfering the rotting process was examined by laboratory and pilot plant studies. The results are pointing to the potential of exhaust gas reduction at MBT plants considering previous control factors and help keeping the standards. The multiple-shift usage of exhaust gas from several plant components of MBT and the thereby caused increase of organic carbon concentrations affects an economical and associated with this an additional ecological benefit. The RTO technology needs energy to maintain the oxidation process. This energy can be supplied by external energy sources or by the energy content of the pollutants in the waste gas. Chapter 5 gives theoretical calculations that show that an autothermic operation could be reached when the organic carbon concentrations exceed 500 to 1.000 mg/m"3 depending on the energy content adopted to carbons in the crude gas. Finally, the collected results are brought together against the background of MBT technology and chances as well as risks that arise from the experimental results appreciated. (orig.) / SIGLE / Available from TIB Hannover: ZA 5140(126) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische Informationsbibliothek / DE / Germany