Application of anoxic phase in SBR reactor to increase the efficiency of ammonia removal in Vietnamese municipal WWTPs

Abstract

Process removal nutrients, especially nitrogen - ammonia in municipal wastewater treatment is a challenger of design and operate wastewater treatment plant. Nowadays in Vietnam, technology SBR has been wide applied in biological wastewater treatment but the concentration of nitrogen - ammonia in treated water cannot achieve the discharge standard. For the purpose to reach the Vietnamese Standard A, the modification of SBR has been added the anoxic phase into operated cycle to create the denitrification's environment and enhance performance of ammonia - nitrogen removal in municipal wastewater treatment at present and in the near future. The results of experiment shows that, the efficiency of N - NH4 removal in reactors sustainable in range 75 - 80% with the nitrogen loadings rate from 0.07 - 0.25 kg N - NH4/kg sludge/d. However, in 3 hours of anoxic phase, the value of specific denitrification rate is 0.10 - 0.15 kg N - NO3/kg sludge/d with the organic loadings rate in range 0.3 - 1.0 kg BOD/kg sludge/d and can reach the maximum is 0.2 kg N - NO3/kg sludge/d when the organic loadings rate increase to 2.0 kg BOD/kg sludge/d.