| Recently, rapid urbanization and industry development has led to more and more municipal sewage was discharged, and the environmental pollution was more and more serious. The high-rate anaerobic biotechnology which was invented in 1970s has gained more and more recognization because it needs low operating and capital costs, the energy can be recovered in the form of biogas and it produces a small amount of excess sludge, especially, it is an good alternative for the developing countries in which the economic development isn't very good and environmental pollution in serious.Large number of municipal sewage was discharged but the concentration of organic contamination is very low, the Expanded Granular Sludge Bed (EGSB) reactor which is the example of the third generation of high-rate anaerobic reactor can achieves high upflow rate and volumetric loading rate, it is appropriate for treatment of low strength wastewater such as municipal sewage, howerer, it hasn't been broad application, and there is little information available in iteratures about this.In this paper, based on the newest relevant research results, we researched the effect of aluminum and alkalinity on the treatment of municipal sewage in EGSB reactor when digested sludge was inoculated, while the referenced value of aluminous polymer and alkalinity used for practical operation were supplied.The result shows that mixing AlCl3·6H2O at a concentration of 350mg/L into the system treating municipal sewage in EGSB reactor can enhance the granulation of anaerobic sludge, diameter of most granule is more than 2mm, the maximum is 6mm. While the methane production and proportion of substrate converting to methane are greatly increased, the maximum volumetric production of methane increased from 7.97×10-3m3/(m3·d) to 50.2×10-3 m3/(m3·d), finally, COD concentration of effluent was less than 90 mg/L.When municipal sewage which has a COD concentration of 180～310mg/L are treated in EGSB reactor, NaHCO3 at a concentration of 500mg/L is sufficient to mitigate the change of alkalinity in the system. Comparing with the system which contains NaHCO3 of 2000mg/L, although the organic loading rate increased slowlier, but it has higher COD removal efficiency and larger amount of methane. At 7th day, the COD removal efficiency has achieved 88.5%, minimum COD concentration in effluent is lower than 10mg/L which is the mimimun value of the test measure, finally, the COD removal efficiency is about 92.1%.
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