Nitrogen removal system and nitrogen removal method of dehydrated filtrate

摘要

PROBLEM TO BE SOLVED: To provide a nitrogen removal system and a nitrogen removal method for dehydration filtrate that reduces a nitrogen load in a water treatment process for treating anaerobic digested sludge.SOLUTION: A fixed amount B of the dehydration filtrate is supplied to a nitrification tank 11, and intermittent aeration is performed while stirring. After a predetermined residence time, the aeration of the nitrification tank is stopped to supply the fixed amount B of supernatant liquid to an oxygen-free tank 13. After the nitrification treatment of the dehydration filtrate, waste water of the nitrification tank 11 and waste water of the oxygen-free tank 13 are alternately exchanged while stirring. Ammonia nitrogen contained in the dehydration filtrate is oxidized into nitrate nitrogen in the nitrification tank 11, and the nitrate nitrogen can be reduced to nitrogen gas in the oxygen-free tank 13. The nitrification tank 11 and the oxygen-free tank 13 can be kept at uniform organic matter concentration by the exchange of waste water, and reduction of the sludge floc of the nitrification tank 11 can be prevented while preventing the pH value from being reduced by nitrification.