Abstract: ObjectiveTo learn effect of purification of wastewater by biological filtration and ozone disinfection.MethodsThe samples were respecttively taken before and after treated by two-stage biological filtration and ozone disinfection.And the sludge suspended particles,PH,CODcr,BOD₅,ammonia,N and Escherichia coli in faecus were determined.ResultsThe oncentr-ations of the indexes as the above reduced significently after wastewater was treated by two-stage biological filtration,and were lower than those of the first class standards made by the national environment buearu,by which two class factories of city and town drain wastewater.The concentration of Escherichia coli in wastewater was lower than that of wastewater draining standard of hospitals.ConclusionIt is effective to treat wastewater by the biological filtration and ozone disinfection.