The Research On Treatment Of Domestic Sewage For Reuse By Submerged Membrane Bioreactor

In this article the optimal operating parameters of MBR were studied. The results were as follows: Using both middle-hole air blowing and micro-hole air blowing could not only reduce membrane fouling, but also supply the microorganism abundance oxygen. The ratio of the gas to water was about 20:1. And the MLSS was about 6⁷mg/L. HRT and SRT were respectively 8h and 8d. On this condition, the average CODcr of effluent of this system was 20.7mg/L, the average BOD₅ of effluent was 8.8mg/L, the average NH₃-N of effluent was 17.9mg/L, and the average turbidity of effluent was 0.9NTU. The quality of the effluent was better than The Criterion of City Wastewater Reuse -Water Quality for City Sundry Use (GB/T 18920-2002).On the basis of former experiments, the influencing factors, such as MLSS, suction time and stop time, were further studied in this system. The results were that reduce suction time or increase stop time and decrease MLSS were good to lessen fouling of membrane, and the primary and secondary order to the effluence of fouling were: suction time > stop time > MLSS. In this thesis there were still experiments of washing the membrane treads. The results showed that cold water could only wash the materials which didn't attach tightly out. Longer time chemical washing was better to clean the membrane both outside and inside, the structure of new membrane almost appeared.On the foundation of the theory from laboratory, a project to treat the waster water from Wuzhou Hospital in Shenzhen by using submerged MBR is set. It started from Dec. 29^th in 2005, and till now the CODcr of effluent is bellow 40 mg/L, the turbidity of effluent is bellow 4 NTU, and the total bacterial have not been checked out. All this shows that the quality of the effluent is better than The Criterion of City Wastewater Reuse -Water Quality for City Sundry Use (GB/T 18920-2002).