Study on nitrogen removal of surface water by MBBR process coupled with sulfur autotrophic denitrification

In recent years, nitrate nitrogenous pollution in surface waters has been extremely serious, while micro-polluted surface water has insufficient carbon sources and high dissolved oxygen levels. Traditional heterotrophic denitrification technology was insufficient to remove nitrate pollution. Therefore, the use of biological autotrophic denitrification technology without additional carbon sources and the formation of an anaerobic environment are the keys to nitrogen removal. In this paper, a sulfur autotrophic denitrification system coupled with the MBBR process was used to study the denitrification of micro-polluted surface water. The results showed that under the condition of influent COD concentration of 62.45 mg/L, after 34 days of stable operation of MBBR-sulfur autotrophic system, the removal rates of NO₃ ⁻-N reached 51.90%, the removal rate of TN reached 31.65%, and the effluent DO was 6.23 mg/L. The single MBBR process had no nitrogen removal effect and even accumulated a certain amount of nitrogen pollution, and the effluent DO was 6.20 mg/L.