Study On The Treatment Of Domestic Wastewater With A New Hybrid Membrane Bioreactor

The lack of water resourse and the contamination of water not only restrict the development of Chinese economy and society, but also do harm to the health of people and affect the harmony and stabilization of society. The only method of solving water question for every country is disposing and circulating the sewage. It has important significance to research new technique for disposing and circulating sewage with low cost and high efficiency.A new hybrid membrane bioreactor (HMBR) was designed in this research. It consists of SBR and membrane unit. The mixture in SBR flows into the membrane unit under gravity pressure. This manner can save power and reduce the operation costs. HMBR has brief composition, no sludge return equipment, running mode and high effluent quality. HMBR will promote the application of MBR technology in sewage treatment field.The operation mode of HMBR was as follows: first, wastewater flowed into the SBR. Then, after the disposal of SBR, the effluent of SBR as the influent of membrane unit flowed into the membrane unit under gravity pressure. Finally, the liquid filtrated through the hollow fiber membrane. SBR operation mode is: instantaneous influent, 5h-anaerobic, 5h-aerobic, 1h-settling, and 1h-drawing-out. The membrane unit was aerated when draw out. The lab-scale equipment was operated stably with no excess waste sludge discharged. The quantity of disposal in one circulation is 50% of whole reactor.The new HMBR process was tested for domestic wastewater treatment. Results showed that the effluent quality was excellent, and came up to the water quality standard of GB/T18920-2002, China. As influent COD, NH₄⁺-N, TP, and TN were 83.2-497.6 mg/L, 7.7-22.5 mg/L, 12.5-29.9 mg/L, and 1.23-3.28 mg/L, respectively, the averaged removal efficiencies were 96%, 96.6%, 54.4%, and 96.9%, respectively.The test device has a relatively high flux in 26.7-33.4 L/m²Â·h in stable operation (average 30.3 L/m²Â·h), far higher than the integrated or seperated MBR. Membrane fouling has been controlled effectively. Results of the cleaning experiments showed that the pollutants are mainly inorganic pollutants and would be better washed by acid than NaOH solution.Microbial examination shows that protozoan and metazoan in HMBR were...