Performance Of Autotrophic/Heterotrophic Denitrifying Ammonium Oxidation Process And The Key Bacteria

A large amount of nitrogen-containing wastewater was produced due to the rapid development of chemical and pharmaceutical fields,which will seriously harm the environment if not treated in time.In many biological nitrogen removal processes,the anammox process is one of the most economical nitrogen removal technologies as it has the characteristics of low treatment cost and good denitrification effect.However,this process requires the use of nitrite as an electron acceptor,and nitrite is an intermediate in the denitrification process can provides the necessary reaction substrate for the process.Based on this,that study used a UASB reactor to couple denitrifying bacteria with anammox bacteria to establish a Denitrifying Ammonia Oxidation process（DEAMOX）.Exploring the key control measures for the high efficient and stable operation of the process that use sulfide（Autotrophic）and（Heterotrophic）p-cresol as denitrifying electron donors.At the same time,high-throughput sequencing technology was used to analyze the changes of microbial community structure during the experiment,and the key microorganisms of the process were identified,which provided theoretical and technical references for the industrial utilization of anammox oxidation.The affect of change nitrite concentration for start-up process and the affect of change S^2-/NO₃^-for operation process were investigated,In the study of autotrophic denitrifying ammonia oxidation process.Experimental results show:（1）The autotrophic denitrifying ammonia oxidation can be achieved by gradually reducing the manner of influent nitrite.The influent nitrite concentration was reduced from 50 mg/L to 0 mg/L under the conditions of 50 mg/L,50mg/L and 76 mg/L of influent sulfide,ammonia nitrogen and nitrate concentration,respectively.The removal rates of ammonia nitrogen and nitrate were changed from 98%and 30%to 78%and 73%,respectively.The autotrophic denitrifying ammonia oxidation process was started successfully,and the overall nitrogen removal effect was well.（2）The change of S^2-/NO₃^-has a significant effect on the effluent morphology of sulfide,nitrate and ammonia nitrogen removal rate.The accumulation of S⁰ was observed in the effluent along with the the influent S^2-/NO₃^-increased,when S^2-/NO₃^-is 1:1 the cumulative amount was up to 70%,and the removal rate of nitrate showed an upward trend,which increased from the initial 61%to 99%;while the removal rate of ammonia nitrogen showed a gradual decline,with the four stages being 98%,90%,70%and 42%respectively.（3）High-throughput sequencing results showed that the sludge microbial richness was higher,the main sulphur autotrophic denitrifying microorganisms is Thiobacillus,Denittrasoma,the main anaerobic ammonia oxidizing microorganism is Candidatus-Kuenenia,their presence guarantees the operation of the autotrophic DEAMOX process.In the study of heterotrophic denitrifying ammonia oxidation process,the feasibility of gradually reducing the influent nitrite to start the process was explored,and the effects of influent substrate concentration and HRT on the stable operation of the process were investigated.The experimental results show:（1）The heterotrophic denitrifying ammonia oxidation can be achieved by gradually reducing the manner of influent nitrite.The removal rates of ammonia nitrogen and nitrate vary from 100%and 10%to 80%and 85%,respectively,during the process of reducing the influent nitrite concentration from 90 mg/L to 0 mg/L,when the influent nitrate,p-cresol and ammonia nitrogen are 53 mg/L,55 mg/L and 66 mg/L,respectively,explain the feasibility of heterotrophic denitrifying ammonia oxidation process.（2）When the influent nitrate,p-cresol and ammonia nitrogen were increased from 53mg/L,55mg/L and 66mg/L to 73mg/L,75mg/L and 91mg/L,the removal rates of the three pollutants varied from 85%,95%,and 80%to 97%,97%,and 70%,respectively;When HRT was reduced from 12h to 4h,the removal rates of the three pollutants were changed from 95%,94%,and 90%to 98%,93%,and 45%,respectively.Indicating that anammox bacteria are more sensitive to changes in operating conditions than denitrifying bacteria.（3）High-throughput sequencing results showed that the main microbial levels of microorganisms were Chloroflexi,Acidobacteria,Proteobacteria,Bacteroidetes,Planctomycetes,Chlorobi.The main anammox bacteria are Brocadiaceae.The main denitrifying denitrifying bacteria are Anaerolineaceae,Caldilineaceae,Comamonadaceae,et al.Their presence guarantees the operation of the heterotrophic DEAMOX process.