Removal efficiency and microbial ecology of internal circulation compound bioreactor for treating low temperature wastewater

摘要

Experiments of domestic wastewater treatment were carried out in laboratory for one year to investigate the effect and microbiology of Internal Circulation Compound Bioreactor process (ICCBR), a combination of activated sludge and modified biological contact oxidation. Ecological factors such as temperature, dissolved oxygen, substrate category and concentration, and COD loading of the system were studied. Results showed that the population and activity of microorganism at low temperature were much less than that at moderate temperature. Six preponderant psychrotrophs were selected out from activated sludge which operating at 4°C for more than one year, belonging to Zoogloea,Aeromonas, Flarobacterium, Micrococcus, Bacillus, Pseudomonas, and the COD removal efficiency of these psychrotrophs was 63.67% higher than that of mesophiles at low temperature. By immobilizing the efficient preponderant psychrotrophs on polyurethane foams, the average COD removal in the ICCBR process was 86.66%. COD loading was kept below 1000 mg/L, the effluent COD is below 100 mg/L. While concentrations of dissolved oxygen in activated sludge process unit and modified biological contact oxidation unit were hold at 2.0 ～4.0 mg/L and 4.0 ～8.0 mg/L respectively, the systemic effluent COD could achieve the first-degree B discharge standard of pollutants in China for municipal wastewater treatment plant.