WASTE LIQUID TREATMENT METHOD AND APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a waste liquid treatment method and apparatus which can use a single reaction tank and treat waste liquid containing tetramethylammonium hydroxide (TMAH) and ammonia nitrogen.SOLUTION: An ammonia nitrogen-containing solution not containing TMAH is introduced into a single reaction tank. Denitrification action is performed on the ammonia nitrogen-containing solution using microorganisms in the reaction tank. The microorganisms include nitrifying bacteria and autotrophic denitrifying bacteria. In the reaction tank, the dissolved oxygen concentration is 0.1-0.5 mg/L and a pH value is 7-8. After the denitrification efficiency becomes stable, TMAH is mixed into the ammonia nitrogen-containing solution, and the addition concentration of TMAH is made lower than 60 mg/L. After the denitrification efficiency becomes stable again, the addition concentration of TMAH is gradually increased.