The pilot plant tests for assessing the application possibility of water channel packing porous concrete to direct purification of polluted river water were conducted. Hence porous concrete provided enough avilable attached area for algae, which was an useful biooxygenproducer, synthetic pollutted river water less than 20mg-TOC/L were sucessfully treated in water channel without deficiency of dissolved oxygen. About 70% of TOC removal was possible under volumetric TOC loading rate below 80 mg/L/day and effluent TOC concentration less than 3 to 4 mg/L could be obtained under volumetric TOE loading rate below 30mg/L/day. Nitrification did not occur in water channel, sothat only 20% of nitrogen was removed. But about 50% of phosphrous was removed by the dissolution of calcium component from porous concrete. Through the SS trapping function of porous concrete, treatment capability of water channel increased tremendously, and the observed sludge yield decreased apparently by the increase of sludge retention time. In water channel packed with porous concrete, filamentous microorganism, such as Geotrichum sp. and Beggiatoasp., andRotariasp., Diplogastersp. andParamecium caudatumwere dominated in the sludge.