Research on optimization of low temperature and low carbon-nitrogen ratio sewage

The anaerobic activated sludge of low temperature and low C/N was acclimated by using SBR reactor for a month, SV kept in 22-24%, the removal rate of effluent COD and NH₄⁺-N were both over 95%. Indicator organisms of the sludge were primarily sessile ciliates. The removal rate of total nitrogen were increased with the increasing of C/N. Perform orthogonal experiment with four factors and three levels on MLSS, pH, DO, C/N. the result showed that the influence of four factors on COD removal was not significant and the main influential factor on ammonia nitrogen removal was MLSS. The optimal conditions of sewage treatment as follow: MLSS between 4000~ 5000mg/L, pH value at 7-8, DO greater than or equal to 4 mg/L. Temperature 10°C, Aeration 7 h. Continuous operating 30d, the removal rate of COD and NH₄⁺-N are both over 95% The removal rate of total nitrogen is reached to 45-64%.