c the gas water ratio therein was 20 1 and the hydraulic retention time therein was 15 h e the wastewater was further treated using flocculating process during which 600 mg l pac was added as a flocculant the final effluent comprised 80 mg l cod 15 mg l bod 5 10 g l suspended solids with ph value 7 and chroma 16 times a mixed wastewater influent to be treated from pharmaceutical chemical industry parks comprised 1 500 2 000 mg l cod 350 600 mg l bod 5 2 100 mg l suspended solids with ph value 8 0 9 0 and chroma 250 times a the mixed wastewater was first introduced into a regulation tank for regulation of water flow and water quality and then into a hydrolysis tank with a volume of 230 l the seed sludge used therein was an anaerobic digested sludge and thickened sludge from urban sewage treatment plants with a concentration of 3 000 5 000 mg l the tank comprised a hanged filler pe pva wire and employed upflow water distribution with a velocity of 1 0 1 6 m h the hydraulic retention time therein was 13 h b the treated wastewater from the hydrolysis tank was introduced into an anaerobic tank with a volume of 450 l and the upflow water velocity therein was 0 5 1 2 m h the seed.