Full scale experiences with small sequencing batch reactor plants in Bavaria

The number of sequencing batch reactor (SBR) plants in operation world- wide has been growing, but scientific process evaluation has not been adequately executed, and very little quantitative information is available on the actual performance of those systems. Trial and error approaches are prevailing. Consequently design engineers and water authorities are left in a rather difficult situation. To get an overview of the performance of SBR plants in operation in the State of Bavaria, Germany, the performance of the existing municipal SBRs has been investigated. The plants investigated comply with the discharge regulations, but in some cases only with the aid of secondary polishing ponds. Most of the system failures observed were caused by inadequate actions of the operators. Energy consumption was in the range of 56 kWh/(PE, a), and excess sludge production varied between 0.25 and 0.81 kg/kg(COD) depending on the influent suspended solid loading.