Start-up Of Anaerobic Ammonia Oxidation And Microbial Community In ASBR

With the development of modern industry and the improvement of people's living standards, a great deal of nitrogen wastewater had been produced and discharged, caused serious pollution of water environment. Although traditional physicochemical and biochemical treatment methods can remove nitrogen from wastewater,there are still some problems need to deal with, for example, complex technological requirements, high cost, the secondary pollution, difficult to treat of low carbon and high ammonia nitrogen wastewater,and so on. Therefore, explore new denitrification theory and develop new denitrification technologies are imperative. Anaerobic ammonia oxidation reaction is the most economic and effective technology for denitrification because of free requirement of organic carbon source and oxygen, short nitrogen transform way, especially suitable for low carbon and high ammonia nitrogen wastewater treatment. However, the ANAMMOX bacteria grow slowly and are difficult to enrich, and, in the practice of the waste water treatment, the inhibitory in the wastewater will also affect the activity of anaerobic ammonia oxidation bacteria, causing reactor start-up difficulties. Therefore, to understand the characteristics of anaerobic ammonia oxidation start-up has important significance for the development of anaerobic ammonia oxidation process.In this paper, the characteristics of anaerobic ammonia oxidation start-up in different pH conditions by 9 test apparatus feed with simulate low carbon and high ammonia nitrogen wastewater and the influence of temperature on the anaerobic ammonia oxidation was investigated. And then, two ASBR inoculated anaerobic granular sludge and concentrated sludge respectively, named R1, R2, were constructed to explore the characteristics of anaerobic ammonia oxidation start-up in ASBR and to investigate the performance of ASBR running under different influent load, DO and organic matter. Finally, the biological population structure and community succession in R1, R2 were investigate to understand the biological treatment mechanism of this process.The results show that the test of P1, P2 and P3 can successful start-up of anaerobic ammonia oxidation in 90 d, 66 d and 69 d, respectively. After 120 d, 99 d, 117 d, ammonianitrogen and nitrate removal rate reached 90%, total nitrogen removal rate reached 60%.The FA and FNA concentration of 0.90~2.19mg/L and 0.00214~0.00537mg/L respectively, is considered the most appropriate concentration to promote the anaerobic ammonia oxidation. The start-up time of P2 is shorted than P1 and P3, therefore, the condition of pH = 7.5 ~ 7.9 is the most suitable for start-up of anaerobic ammonia oxidation. The results of influence of temperature of 30 ?, 20 ? and 10 ? on anaerobic ammonia oxidation showed that the optimum temperature of anaerobic ammonia oxidation reaction is 30 ?.The reactor R1, R2 can successful start-up anaerobic ammonia oxidation after reaction in106 d and 91 d respectively. The ammonia nitrogen, nitrate nitrogen removal rate can achieve above 90%, the removal rate of total nitrogen in R1 is about 50-60%. The removal rate of total nitrogen in R2 is about 45-55%.After running of four mouths, the filamentous bacteria and chain bacteria to be being washed out gradually, and spherical bacteria and bacillus bacteria become dominant species.The average coefficient of sludge production is 0.26 mol/mol in R1 and 0.218 mol/mol in R2,suggest that anaerobic granular sludge is more suitable as inoculation sludge for start-up anaerobic ammonia oxidation.The ammonia nitrogen and nitrate concentration in influent is 25-53 mg/L and 34-71mg/L in reactor R1 respectively. The removal rate of the ammonia nitrogen and nitrate is over90%, total nitrogen removal rate is in 50-60%. When the ammonia nitrogen and nitrate concentration in influent increased to 67-72 mg/L and 92-102 mg/L, the removal rate of ammonia nitrogen and nitrate is about 89-93%, 84-91%, the removal rate of total nitrogen is about 60%.When the influent without deoxidization treatment, the activity of nitrifying bacteria will recover in the reactor, the anaerobic ammonia oxidation bacteria will be restrained, the total nitrogen removal rate reduced to 40%-50%. If the influent deal with deoxidization process,anaerobic ammonia oxidation bacteria will recover activity, the total nitrogen removal rate is about 65%; water deoxidization contributes to total nitrogen removal, improve the efficiency of anaerobic ammonia oxidation reaction.With the COD concentration of 120 mg/L, the ammonia and nitrate concentration in influent raised to 67-78 mg/L and 92-102 mg/L respectively, the removal rate of ammonianitrogen and nitrate were 95% and 96%, respectively as well as the total nitrogen removal rate is about 70%. The collaborative symbiosis phenomenon of denitrifying bacteria and anaerobic ammonia oxidation bacteria appeared in the reactor.The PCR- DGGE analysis and sequencing results show that, with long time running of two reactors under the anaerobic environment, the biological population structure and community succession pattern have great changes in the reactor R1 and R2. The characteristic of microbial similarity gradually reduced with the running time as well as the species diversity index decreases. The diversity of microbial population in R1 reduced from 2.82 to2.82, while the reactor diversity of microbial populations in reaction R2 reduced from 3.26 to3.26. With the operation of the reactor, the population of microbial has gradually reducing,some of the aerobic and heterotrophic bacteria to be washed out gradually, and some new anaerobic bacteria appeared at the same time. The dominant population in the two the reactors is Proteobacteria.