BIOLOGISK KVÄVEREDUKTION FÖR KOMMUNALA OCH INDUSTRIELLA AVLOPPSVATTEN / Biological Nitrogen Reduction in Sewage and Industrial Wastewater
The demand for more efficient wastewater treatment in Sweden and Denmark has increased lately. The demand for nitrogen removal has especially increased in Sweden, where this means that nitrogen has to be removed with 50 % to begin with and 75 % for some areas later on. In Denmark the general requirement is a maximum effluent quality of 8 mg/l total nitrogen. Activated sludge systems with nitrification and denitrification will be the dominating processes for nitrogen removal. The theoretical function of the processes for nitrogen removal is described together with different treatment systems developed. Fullscale plants constructed by PURAC AB are already in operation and several pilot plant tests have also been carried out. The systems used are mainly with pre-denitrification.