Experimental Study On Treatment Of Municipal Wastewater In Cold Region With Combined Biological Process

Biological process is considered as one of the most significant methods in wastewater treatment. As an increasing popular method to treat wastewater, the operation state determines the treating efficiency and performance as well as capital and operating costs of the whole system. The treating system often faces the instability in eliminating pollutants, the activity of microorganism is restrained due to the physiological nature of microorganisms. Therefore, it is needed to investigate the performance of biological process in cold-weather area in order to determine reasonable parameters for stabilized and well treatment efficiency of the system. This study is mainly focusing on treating low temperature domestic wastewater using so-called hybrid bioprocess. The contents include three aspects as (i) overall performance of hybrid reactor in removing pollutants from domestic wastewater; (ii) the characteristics of microorganisms in the system; (iii) constructing kinetics models of the system. The results obtained here did provide both important conclusions and technical advices in developing the operational performance of hybrid bioprocess in wastewater treatment plants that are located in north area.In the paper, the effect of hydraulic retention time (HRT) on treatment efficiency was investigated and the theoretical hydraulic retention time (HRT) of hybrid system was constructed using famous Lawrence-McCarty theory on the basis of the principle of microorganism reactions as well as mass balance. Meanwhile, the formula was simplified based on microorganism-kinetics as affecting factors by means of orthogonality experiments. Then the best HRT for HBR system was educed,the factual HRT was gain and testified based on the experimental study on the effect of HRT on treatment efificiency.The effect of return sludge ratio (R) on treatment efficiency was also investigated. The results demonstrated that the increased R could enhanced the MLSS of activated sludge but has little influence on the biofilm; the activity of sludge and biofilm decreased with the increase of MLSS. The nitrobacteria in...