Research And Mechanism Analysis On Polluted River Remediation Using Bio-contact-oxidation Process

As the economic developing quickly,more and more pollutants were discharged into the city rivers,so that the city rivers have been seriously polluted.The river pollution has caused the water resource problem,affected the citizen's health,and also limited the economic development.The river pollution has been the key limiting factor of the sustainable development.Now we all realize the damage and risk of river pollution.To control the city river pollution,effective measures must be made as soon as possible.This paper used the bio-film contact oxidation process to control the river pollution. According to the river characteristic,we made a pilot test model of polluted river,using bio-film carrier,hybrid super bacteria and microporous tube aeration process to treat the sewage water.This experiment would find out the mechanism of the bio-film contact oxidation and assess the pollution removal efficiency.During the bio-film hanging process,we analysised the COD_Cr,NH_3-N,NO₂^--N, NO₃^--N,TN,TP concentration of the influent and outfluent water.The results indicated that:COD_Crconcentration could reduce quickly,while the bio-film hanging process ahcieved,the COD_Crconcentration was less than 40mg/L;the NH_3-N concentration reduced slowly,because the nitrobacterier's generation time was longer,after 15 days from the beginning day,the NH₍3-_N concentration was less than 1mg/L;the TP concentration was higher than 2mg/L,and the concentration was steady,the bio-degradation was very low;in higher DO level,the denitrify was very low,TN could not be removed.According to the change of DO and water temperature,this paper found out that while the water temperature was within 10 to 20℃and the DO level was in high level, the effect of COD_Crremoval would raise while the temperature raised.Using MPN counting and FISH method,this paper found out that Ammonia-oxidizing bacterias and nitrite-oxidizing bacterias were distributed into the zoogloea.The change of NH_3-N, NO₂^--N,NO₃^--N concentrations indicated how the nitrify system developed.Using SEM analysing the micro-morphology of zoogloea,this paper found out that the bio-film carrier could block the zoogloea and the zoogloe adhered at the carrier to grow up.After a month,the zoogloe looked like a filiform frame.Such frame could adhere the pollutants and was good for the bio-film growth.While the bio-film hanging succeeded,the bio-film had little protozoan and algae.The algae simpson diversity index increased as the water flowed.The protozoan simpson diversity index decreased as the water flowed.In the systemic adjustment,this paper found out that while the COD_Crwas in a higher load,the effluent COD_Crconcentration could still be at a low level within 40～50mg/L.While the influent NH_3-N concentration was less than 40mg/L,the effluent NH_3-N concentration was less than 1mg/L;While the influent NH_3-N concentration was larger than 60mg/L,the nitrify system would be destroyed,the effect of NH_3-N removal would be decreased in a large degree.Because the bio-film became thicker,the mass transfer resistance was raised,so the best DO level was 3-4mg/L.While the bio-film became thicker,the inner bio-film had anaerobic layer which had denitrify effect,so the TN had 30%removal.Bio-film contact oxidation has very good effect in COD_Cr,NH_3-N removal,and the effluent concentration can reach the fifth grade standard of surface water,but the TP removal effect is very low,the TP removal needs further research.