BIOLOGICAL NUTRIENT REMOVAL APPLIED TO WEAK SEWAGE

The Melby Wastewater Treatment Plant is located in the municipality of Frederiksvaerk on the island of Sealand, Denmark. This may be the first full-scale plant in Europe purpose built for biological nutrient removal from diluted wastewater, i.e. weak domestic wastewater mixed with infiltration waters. The relatively strict effluent standards have required the existing treatment plant to be upgraded in capacity, including the design for biological Nitrogen and Phosphorus removal. Due to the weak nature of the influent wastewater, the treatment process that has been adopted includes the application of a primary sludge fermenter to alter the influent characteristics suitable for biological nutrient removal. The treatment process used is the Modified University of Cape Town process utilising a primary sludge fermenter developed ar the University of British Columbia in Canada. The combination of these two processes has bees successfully applied to meet the strict. discharge licence requirements, without the addition of chemicals, despite the unsuitable characteristics of the influent wastewater for biological nutrient removal. The paper describes the operational results for the treatment plant.