Study Of Microecosystem Community Of Bioremediation Technology On Plant Roots And Medium Biofilm In Malodorous Black Water

In recent years,pollution Sources and pollutants dramaticly increased with the rapid urban population growth and the rapid development of industry and agricultural, so the ecological environment of much polluted water become seriously unbalanced. Nitrifying bacteria is one of the micro-organisms that paly an important role in biological nitrogen removal,which will directly affect the nitrification effects and the efficiency of the biological nitrogen removal.Ammonia oxidizing bacteria(AOB)and Nitrite oxidizing bacteria(NOB)cooprate to converse NH₄⁺-N to NO₂^--N.They became the main bacteria to study because of its slow growth and the sensitive to the hocking.The efficiency of the nitrogen removal is determined by bacteria community composition.Therefore,comprehensive study on species,numebers and distributions of nitrifying bacteria and optimal control are the keys to ensure the wastewater treatment system is stable and efficient,which has became the world's hot spots.Based on the functions of carbon,nitrogen and phosphorus removal,the A²/O process is becoming one of the Mainstream technologys in Urban sewage plants.But, the process has been restricted by its multiple self-factor.Meanwhile,the wastewater of combined sewage system has changeable special characteristics of low C/N.So, improving the function and extending application of A²/O process has become the new subject in wastewater treatment field.This thesis is based on the project of process technology upgrade and transform in wastewater treatment plant supported by Shanghai Committee for Urban Construction and Transportaion.By simulating real system of Bailonggan wastewater treatment plant,the research investigated the impact effect to the treatment denitrification efficiency by external control(including temperature,F/M,enhancing ANAMMOX technology and low C/N shocking and restoring),and analyzed the change of the community structure of the Nitrifying bacteria and the Species diversity by using PCR-DGGE technology.The research can provide technical basis to guarantee the stable and efficient nitrogen removal efficiency of the A²/O process.The results showed that the temperature and the processing functions of A²/O process were closely related.And the seasonal change had some negative effect on nitrogen removal efficiency.The temperature range of 25℃～30℃was the best for denitrification,and too high or too low temperature could inhibit function of nitrogen removal.In this temperature range,the removal rate of TN was about 70%: nitrification could reach to 95%.The fuctuations of temperature could affect the community structure and the Shannon diversity index of nitrifying bacteria.The species of community was relatively abundant when the temperature was low,but the community structure was stable when the temperature was high.The best range of F/M for denitrification was 0.125～0.23gBOD₅/gMLSS·d.The best range of F/M for nitrification was 0.14～0.28gBOD₅/gMLSS·d.In summar,the best range of F/M for the A²/O system was 0.14～0.22gBOD₅/gMLSS·d.It was slightly higher than the design standard of A²/O.F/M could affect community structure and the Shannon diversity index of nitrifying bacteria.When F/M ranged between 0.03～0.44gBOD₅/gMLSS·d,nitrobacter became the dominant species of NOB.The results of shocking and restoring experiment showed that the nitration function could be greatly limited by wastewater of which C/N was 3.5,and the denitrification function could completely stop when C/N was 1.2.Increasing reflux ratio could effectively shorten restoration time,and the removal rate of NH₄⁺-N and TN could be improved 20%and 7.4%respectively.Increasing F/M and lowering SRT could also improve the nitrogen removal function of system,the removal rate of NH₄⁺-N and TN could be improved about 5%and 4.7%respectively.The method could also improve the bioactivities of sludge,and the nitrification OUR and nitrosification OUR could be improved about 7%and 5.7%respectively.The methods mentioned above restored the community structure of AOBs and nitrobacter of NOBs very well,but it affected nitrospirs of NOBs little.Enhancing the nitrogen removal function of A²/O process by ANAMMOX technology was an effective way.The results showed that lowering DO in aeration tank cloud result in effective accumulation of NO₂^--N,enhance ANAMMOX function, and strengthen nitrogen removal in the system.More 15%NH₄⁺-N and more 9%TN could be removed respectively in the anoxic tank.More 7%TN could be removed in the whole system.TN removal by ANAMMOX is account for 21.9%of TN removal rate in system,the reaction medium was NH₄⁺-N and NO₂^--N,and generated small amount of NO₃^--N in reaction process.The proportion of those factors was 1:1.256:0.155;the best range of pH for ANAMMOX reaction was 7.8～8.0.DO could restrict ANAMMOX,and temperature had great influence to the reaction rate.The reaction rate decreased from 1.47mg/Lh to 1.175mg/L.h when temperature changed form 30.6℃to 24.6℃.Some dominant species of AOBs still can nitrosate in the A²/O process enhancing ANAMMOX function,while ANAMMOX bacterias also exist in the traditional A²/O process,which oxidate and reducte NH₃-N and NO₂-N to N₂.The community structure and the Shannon diversity index of ANAMMOX bacterias in both processes will be affected by shocking of low C/N.Compared with traditional A²/O process,the restoring result of community structure of ANAMMOX bacterias in A²/O process enhancing ANAMMOX function is better.