| dc.description.abstract | In recent years, many sewage treatment plants incorporate biological processes which can remove phosphorus and nitrogen simultaneously. In order to reclaim treated water, membrane bioreactor systems (MBR) are further included. How to control the nitrogen and phosphorus environment and biological treatment units with MBR process ? And what is the different with the traditional secondary settling tank return sludge, will be the focus of this study.
In this study, 6,000 tons of modified A2O + MBR system were used to study the changes of water quality and control conditions of anaerobic tank, anoxic tank and oxic tank (built-in MBR) in real flow conditions, discussion on the treatment efficiency of pollution load.
The results show that the A2O system only nitrification and almost no denitrification, total phosphorus almost no removal rate; The removal rate of BOD5 and COD was very significant in the MBR system, and the removal rate was above 99 %. At the same time, the MBR had the function of removing ammonia and total phosphorus, the average removal rate was 36.57 % and 74.10 %, the average of total dissolved solids were 292.20 mg/L, indicating that the salt or metal ions in the water could not be separated by the MBR; In modified A2O + MBR system, The average removal rate of suspended solid、BOD5 and COD was 97.45 %、95.57 % and 92.79 %, and the removal rate was not affected by the concentration of MLSS in the oxic tank. After treatment, the average removal rate of ammonia was 3.57 mg/L, and the average removal rate was 85.68 %. The nitrification could be carried out in oxic environment due to sufficient dissolved oxygen. Total phosphorus is limited by the concentration of sludge uptake and storage, and the total phosphorus content after sludge discharge can be reduced but the effect is limited. The nitrification sludge and the return sludge are all from the MBR tank, the membrane tank needs aeration to keep the membrane swing, so that when the sludge back to the anaerobic tank and the anoxic tank, due to the dissolved oxygen of sludge is too high lead to denitrification and phosphorus release is not significant. | en_US |