The total bio-film mass under the highest organic loading of 1340 g BOD5/m3 d was 52.3G0.47 g while it was only 35.5G0.21 g under the lowest organic loading of 500 g BOD5/m3 d. The total bio-sludge mass values of the system under organic loadings of 1340 and 500 g BOD5/m3d were 112.3G13.1 and 91.5G8.6 g,respectively.