Rapid Culture Of High-efficiency Denitrifying Bacteria And Analysis Of High-efficiency Denitrifying Bacteria And Embedding Filler Performance And Application

The existing processing efficiency cannot fundamentally achieve the purpose of saving energy and reducing consumption in the wastewater treatment plant,causing high operation cost of sewage treatment facilities.At the same time,Nitrate nitrogen concentration in the surface water can not be effectively reduced by conventional water treatment unit.For the above two major problems,put forward that cultivate high-efficiency denitrifying bacteria by using fermented liquid to improve the efficiency of wastewater treatment;study adaptability and recovery capability of high-efficiency denitrifying bacteria and their embedding fille to examine the engineering application value;high-efficiency denitrifying bacteria embedding filler is used to different temperature surface water.The main research results are as follows:High-efficiency denitrifying bacteria can improve wastewater treatment efficiency.In order to rapidly culture high-efficiency denitrifying bacteria,batch trials were conducted at different carbon source?No.1 and No.2 fermented liquid?and NO₃^--N concentration gradient(30 mg·L^-1-150 mg·L^-1-300 mg·L^-1).The results demonstrate that No.2 fermented liquid could finish high-efficiency denitrifying bacteria[300 mg·?L·h?^-1]cultivation in 11 d,which is 17 d in advance as compared with No.1 fermented liquid.At the same time,high-efficiency denitrifying bacteria can effectively remove ammonia nitrogen and total phosphorus,and maximum removal rates are 34.43 mg·?L·h?^-1 and 2.98 mg·?L·h?^-1 respectively.Furthermore,high-throughput sequencing is employed to characterize and compare the community structure and diversity,the results show that the species abundance and diversity are reduced,but the category and proportion of denitrifying bacteria are increased.In addition,bacteria composition and quantity has changed after cultivation,and finally Thauera and Pseudomonas are dominant contributors for effective removal of nitrate in the SBR.Denitrifying phosphorus accumulating bacteria?Rhodocyclaceae and Pseudomonadaceae?and heterotrophic nitrification bacteria?Pseudomonas,Alcaligenes,Bacillus and Comamonas?proved the system's capacity to remove ammonia nitrogen and total phosphorus.In order to study adaptability and recovery capability of high-efficiency denitrifying bacteria and their embedding filler to low temperature and low substrate concentration,the test was performed under 2 conditions?favorable and unfavorable?and 3 stages?D₁,D₂ and D₃?to explore their denitrifying capability,the favorable condition:reacting temperature of 30?,nitrate concentration of 300 mg·L^-1 and C/N ratio?10?,and the unfavorable condition:reacting temperature of 4?,nitrate concentration of 30 mg·L^-1 and C/N ratio?5?.In stage D₁,high-efficiency denitrifying bacteria[300 mg·?L·h?^-1],which was cultured at favorable condition,was placed under the unfavorable condition.In stage D₂,embedded the bacteria after the denitrifying performance was stable,and still placed the bacteria embedding filler under the unfavorable condition.And then recovered to the favorable condition?D₃?after 90 days.The results show that the denitrification rate of the stage of D₁ and D₂ is finally stabilized at 5.4mg·?L·h?^-1 and 4.8mg·?L·h?^-1 after operation of 17 d and 16 d respectively,indicating that the bacteria and their embedding filler can adapt to the unfavorable conditions of low temperature and low substrate concentration;in D₃stage,the denitrifying rate of the filler could reach 300mg·?L·h?^-1 after operation of only 12 d,indicating that the filler has rapid self-recovery capability.The scanning electron microscope?SEM?was utilized to analyze the internal and external structures of the embedding filler and find that both the internal and external structures are favorable for bacteria growth metabolism and mass transfer.The high-throughput sequencing analysis results show that the dominant genus in D₂ stage are still Pseudomonas,Thauera and Gelidibacter with the denitrifying functions,thereby proving adaptability of the bacteria under the unfavorable condition;the dominant species Thauera,Petrimonas and Pseudomonas of the embedding filler in D₃ stage are completely same as the dominant species of the high-efficiency denitrifying bacteria cultured under the initial favorable condition,which also fully prove that the bacteria embedding filler have good recovery capability.NO₃^--N was the main form of N that exists in surface water.Experiment proved that denitrification embedding filler with high-efficiency denitrifying bacteria had better adaptability to seasonal changes in temperature.Results showed that using nitrate concentration of 30mg/L and C/N ratio?4?,fillers embedded with denitrifying bacteria exhibits strong adaptability to low temperatures and achieved denitrifying rates of 2mg/?L·h?,4.3mg/?L·h?,8.7mg/?L·h?at the temperatures of at 4±1?,15±2?and 29±1?respectively.Results from high-throughput sequencing analysis revealed that the dominant bacterial community of high-efficiency denitrifying bacteria in different temperature range changed to adapt to varying temperature.The system at 15±2?had the greatest diversity and abundance.The top three types of dominant bacterial community were Comamonadaceae_norank,Pseudomonas,WCHB1-69_unculturedbacterium,Thauera,Comamonadaceae_norank,WCHB1-69_uncultured bacterium and Thauera,WCHB1-69_uncultured bacterium,Petrimonas,respectively.