ANVÄNDNING AV SYRGAS FÖR FÖRBÄTTRAD NITRIFIKATION VID KALLA TEMPERATURER Fullskaleförsök vid Slottshagens reningsverk i Norrköping vintern 1991-92 / The Use of Oxygen Gas for Improved Nitrification at Low Temperatures Full scale experiments at Slottshagen WWTP in Norrköping during the winter 1991-92
From February to April in 1992, oxygen gas was introduced in one of six aeration basins at the Slottshagen waste water treatment plant in Norrköping, Sweden. During this period the nitrification activity is usually very low and the oxygen levels in a large part of the aeration basins are below 1 mg/l. As oxygen was dosed, profile analyses and grab samples of effluent from two basins was analysed. This procedure indicated an increase of nitrification of approximately 4 mg/l of nitrogen. The dissolved oxygen level in the treated basin improved faster to approximately 2 mg/l, a condition favorable for nitrification. The aerobic retention time was therefore longer in the treated basin. This increase in nitrification corresponds to 29 kg of oxidized nitrogen per day and was achieved through the addition of 281 kg of oxygen. This figure represents 48 % of the theoretical value and it was accomplished at a cost of 20 SEK/kg of nitrogen oxidized. The usage of oxygen gas can be adjusted to the demand and further optimized. “Complete abstract not presented.”