Marine Heterotrophic Nitrification - Aerobic Denitrifying Bacteria Synchronous Nitrogen And Carbon Removal Characteristics

This study successfully isolated three strains heterotrophic nitrification-aerobic denitrification bacteria from Bohai Bay seabed sediments,which named y3?y5 and y6.According to the morphological observation,physiological biochemical test and16 S rRNA genesequence analysis,strain y3 was identified as Pseudomonas sp.strain y5 and y6 was identified as Klebsiella sp.We have investigated three different effect factors effecting the degradation characteristics such as carbon resource,pH and C/N to get the optimal degradation conditions.The study found that the strain y6 was able to use sodium acetate,sodium succinate,sodium citrate,glucose and sucrose,the best carbon source was sodium citrate.The optimum pH was 7.0,the optimum C/N was 17.Strain y6 had better heterotrophic nitrification-aerobic denitrification reactor in the reaction symtem of NH4Cl?KNO3 and NaNO2 for the only nitrogen source and in the different mixing ratio of reaction system.In the reaction symtem of NH4Cl?KNO3 and NaNO2 for the only nitrogen source,The removal rate of NH4+-N?NO2--N and NO3--N is 99.67%?100% and 99.20%,The removal rate of COD is 82.17%?95.75% and 97.83%?The accumulation of NO2--N and NO3--N in the process of nitrification was small,and the results showed that the strain y6 had a special ammonia nitrogen nitrification pathway.In the mixed reaction system,the strain y6 first used NO3--N to carry out aerobic denitrification,and then the NH4+-N,NO2--N and COD were simultaneously degraded.In the NO3--N : NO2--N were 1:1,1:2,1:3,2:1,3:1 system,the removal rate of NO3--N was 100%,the removal rate of NO2--N was 99.64%,99.71%,99.76%,99.67%,99.12%,the removal rate of COD were 95.71%,90.37%,85.34%,84.79%,83.93%.In the NH4+-N: NO3--N were 1:1,1:2,1:3,2:1,3:1 system,the removal rate of NO3--N was 100%,the removal rate of NH4+-N was:100%?100%?100%?91.97%?91.93%,the removal rate of COD was 90.22%?87.94%?79.18%?74.18% and 73.49%,In the NH4+-N: NO2--N were 1:1,1:2,1:3,2:1,3:1 system,except 1:3 system's removal rate of NO2-_N was 99.47%,other system's removal rate of NO2-_N was 100%,the removal rate of NH4+-N was 88.00%?84.17%?84.63%?97.93%?94.21%,the removal rate of COD was 83.89%?85.77%?88.62%?82.31% and 82.07%,In the system of NH4+-N?NO3--N and NO2--N was 1:1:1,the removal rate of NH4+-N was 86.81%,the removal rate of NO3--N and NO2--N was 100%,the removal rate of COD was 92.91%?In this experiment,three strains of heterotrophic nitrification and aerobic denitrification bacteria were expanded after cultured separately in 3 the same biological filter,study three strains treatment effect in SBR reactor,changes of microorganisms on marine aquaculture wastewater treatment process and the strain's operation stability in the reactor in the long period.First of all,three strains of bacteria were enhanced,then deal with simulated marine aquaculture wastewater in SBR reactor.The influent concentration of NH4+-N was at 50~60 mg/L,COD's concentration was at 600~700mg/L.Three strains after pre adaptation into a stable period,when y3 was in 70 days and 140 days,y5 was in 105 days and y6 was in 122 days the removal rate decreased,after soil discharging the reaction system was gradually restored,the ammonia removal rate of y3 is stronger than that of y6 than y5,the stability of y6 is stronger than that of y5 than y3.In stable phase the ammonia nitrogen removal rates of y3,y5 and y6 were about 92%,88% and 90%,respectively.After soil discharging,the removal rate of ammonia nitrogen was decreased,Three strains of COD had little difference in the vicinity of 90%.The reaction time of y3,y5 and y6 were 5h,3h and 4h.Nitrogen removal and carbon removal simultaneously,the fastest degradation rate was in the middle,early and late,respectively.NRR was about 0.26 kg.(m3.d)-1?0.4 kg.(m3.d)-1 and 0.32 kg.(m3.d)-1,ORR was about 2.7 kg.(m3.d)-1?4.8 kg.(m3.d)-1 and 3.6 kg.(m3.d)-1?Three all have a process from the loose to the condensation in the formation of the sludge zooglea.The sludge concentration increment y6 greater than y3 than y5 was 6.1 g/L,4.7 g/L,and 7.6 g/L,respectively.The sludge sedimentation performance of y3 and y6 had little difference,y5 was poorer.During the operation of SBR reactor y3 first turned black then y5,and finally y6,From the initial milky white to yellow and finally to black.Obseringand some protozoa such as Paramecium under the microscope,they have a positive effect on flocculation.