We investigated the association of Chlorella vulgaris and E. coli W9110 in removal of total organic carbon with the lab-scaled continuous river water flow system (CRWFS). Artificial wastewater was applied at two levels of organic carbon concentration; 1,335 $mg{cdot}l^{-1}$ in the treatment (T)-1 and 267 $mg{cdot}l^{-1}$ in T-2. The highest densities of C. vulgaris were $8.3{ imes10^6;cells{cdot}ml^{-1}$ in T-1 and $6.9{ imes}10^6;cells{cdot}ml^{-1}$ in T-2. The maximum densities of E. coli W3110 were $2.0{ imes}10^8$ clony forming unit (CFU)${cdot}ml^{-1}$ in T-1 and $3.9{ imes}10^8;CFU{cdot}ml^{-1}$ in T-2. The densities increased during the first 11 days in T-q and 4 days in T-2, and decreased rapidly till 35th day, then increased slightly afterwards. This trend was prominent in T-2. It was inplied that wider range of nutrients was required in the growth of heterotrophic bacteria in T-2 than in T-1. The algal biomass should be increased effectively for the successful removal of organic carbon.