Post denitrification in a moving bed biofilm reactor process

The Sjölunda wastewater treatment plant in Malmö Sweden will have to comply with future effluent standards of less than 10 mg BOD₇/l, 8 mg N/l and 0.3 mg P/l. The upgrading for enhanced nutrient removal will be based on a site-specific concept where a tertiary treatment step for post-denitrification will be required. An interesting process in this respect is the moving bed biofilm reactor (MBBR). The number of practical experiences with this type of process is however still limited. In this paper the results from a pilot plant test are presented. The primary aim of the experiment was to demonstrate the MBBR process as part of an overall concept for nutrient removal at the Sjölunda WWTP. Two different carbon sources, ethanol and methanol were tested. In addition the effect of low phosphate concentrations on the process performance was investigated.