[Efficiency analysis of two-stage SBR for phosphorus nitrogen and organic substrate removal]

Taking simulated domestic sewage as treatment object, the characteristics of separate-stage phosphorus, organic substrate and nitrogen removal were studied in two-stage SBR by contrast experiment and mechanism analysis under the normal temperature, its efficiency-predominance was analyzed. The results indicate that the heterotrophic PAOs and nitrobacteria can be dominant growth in individual reactor respectively, under the effluent quality is more superior, the treatment efficiency is one time higher than that in the single SBR by controlling the sludge age (the phosphorus removal stage 5-7 d, the nitrogen removal stage about 50 d). The two-stage SBR can relieve the attack of organic load to nitrification process effectively, its nitrogen removal stage (SBR2) can still maintain stable nitrification rate under the higher COD concentration and the final effluent of the system is easy and stable to reach national standards (TP < or = 0.5 mg x L(-1)). In addition, the nitrogen removal stage (SBR2) of two-stage SBR not only can maintain nitrobacteria predominant, but also can cultivate heterotrophic bacteria which can remove difficult degraded organic substrate, that results in lower COD concentration than in the single's at the end of nitrification.