Bacillus sp. (M-12) was able to decrease the chemical oxygen demand (COD) of the waste water significantly. Polyvinyl Alcohol (PVA) was chosen to immobilize the bacterial cells and the immobilized cells could be used for waste water treatment for many cycles with high COD removal efficiency. The efficiency of decreasing COD could be improved when a nitrogen source such as (NH4)(2)SO4 was added into the waste water. A continuous waste water treatment system with immobilized cells and a cinder column was developed and this continuous system had a significant effect on decreasing the COD of the waste water, which could be reduced from 2600 to 240 mg/L. (C) 2004 Elsevier Ltd. All rights reserved.