Study On The Screening And Enrichment Of Residential Functional Bacteria From Polluted River And Their Purification Performance

Surface water pollution has been a serious problem for a long time in China.Residential microbial intensification and remediation technology has become a research focus in the field of water pollution bioremediation,with its advantages of high efficiency and little damage to river’s ecological environment.The mixed microbial community has obvious advantages in removing pollutants because of its more adaptive to the environment than that of a single strain.Therefore,this project screens and enriches residential functional bacteria from polluted river,and investigates their purification performance.Heterotrophic nitrification-aerobic denitrifiers community（H）,heterotrophic nitrifiers community（Y）and aerobic denitrifiers community（F）were successfully enriched from river sediment by selective enrichment medium.High-throughput sequencing revealed that the relative abundance of functional bacteria in each community was identified as 54.72%,48.36% and 92.85%,respectively.Further effects of trace elements on nitrogen removal performance were investigated for three denitrifying communities.The results showed that H and F exhibited the best nitrogen removal performance when trace elements were added at 0.5 ml/L.The removal efficiencies of ammonia and nitrate by H were 69.11% and 99.05% after 72 hour,and the removal efficiencies of nitrate by F reached 99.62%.However,the removal efficiency of ammonia was the highest at 82.60% by Y when no trace elements were added at the 72nd hour.The method of gradually adding actual river water into medium was successfully adopted to domesticate the optimized denitrifying communities.Then inoculating these three domesticated single and their compound communities（H+Y,Y+F,H+F,H+Y+F）into simulated river water respectively,the compound communities（H+Y+F）showed the highest nitrogen removal efficiencies.And it could continue to repair simulation of polluted river water at the optimal dosage 0.75 g/m³（cell dry weigh）.The experiment results show that the compound communities（H+Y+F）has potential application value for the purification of actual polluted river water.We inoculate the compound community H+Y+F to the actual river water with the cell dry weight of 0.75 g/m³ to study water treatment effect.We found that the nitrogen and CODcr indicators in the inferior Class V river water（initial DO:4.02 mg/L）polluted by rainwater can be restored to the surface water Class V within 72 hours without aeration.Combined with continuous aeration of 0.4 L/min（air meter）,the microflora H+Y+F has the most advantageous at the removal of pollutants in the river water damaged by sewage.The removal efficiencies of NH₄⁺-N,NO₃^--N,TN and CODcr within 24h were up to 42.31%,38.73%,41.83% and 68.86%.High-throughput sequencing results show that the removal of pollutants in water were related to the heterotrophic nitrification-aerobic denitrification bacterias,both in rainwater and sewage impact channel reactors.Among them,Flavobacterium was significantly associated with nitrogen and organic removal.