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 fir st full-scale plant in Europe purpose built for biological nutrient re moval from diluted wastewater, i.e. weak domestic wastewater mixed wit h infiltration waters. The relatively strict effluent standards have r equired the existing treatment plant to be upgraded in capacity, inclu ding the design for biological Nitrogen and Phosphorus removal. Due to the weak nature of the influent wastewater, the treatment process tha t has been adopted includes the application of a primary sludge fermen ter to alter the influent characteristics suitable for biological nutr ient removal. The treatment process used is the Modified University of Cape Town process utilising a primary sludge fermenter developed ar t he University of British Columbia in Canada. The combination of these two processes has bees successfully applied to meet the strict. discha rge licence requirements, without the addition of chemicals, despite t he unsuitable characteristics of the influent wastewater for biologica l nutrient removal. The paper describes the operational results for th e treatment plant.