| The acceleration of industrial,agricultural development and urbanization led to the excess nitrogen emissions,which not only cause great environment pollution problem,but also threat human health.How to control the nitrogen pollution has become a major issue to solve for the contemporary researchers.The traditional biological denitrification technology is widely used.However,there are many problems such as high capital cost,large covering areas,long process and not too mature operation control technology.In the new biological nitrogen removal technology,anaerobic ammonium oxidation(ANAMMOX)process has broken the basic nitrification and denitrification theory of the traditional biological denitrification technology,which becomes a recognized economic,efficient,environmental friendly and sustainable denitrification pathway.However,there are a lot of problems to be faced on applying anaerobic ammonium oxidation to the actual sewage treatment project.For instance,the anaerobic ammonium oxidation bacterium(AnAOB)grows slowly,sludge concentration is difficult to further improve and the denitrification effect is easy to be affected by environment.These issues seriously restrict the development of ANAMMOX denitrification technology.Our research used the single stage nitrogen removal using anammox and partial nitritation(SNAP)reactor which effective volume was 80L.The biofilm packing was fixed in the reactor and it started up by adding seed sludge with anammox activity,the object of experimental processing was artificial simulation of ammonia nitrogen sewage with a concentration of 50～2000mg/L.The effects of temperature,pH,oxidation reduction potential(ORP)and other factors on the denitrification performance of the reactor were studied by continuous flow method.Also,the species in microbial community structure and sludge in the nitrogen loading rate(NLR)of 2kg-N/m3/d were analyzed.After starting,the experiment proceeds load,resistance to concentration,alkalinity,temperature and re-start the reactor experiment were finished,The main results were as follows:(1)The nitrification sludge and the anaerobic ammonium oxidation sludge were mixed as seed sludge according to a ratio of 1:5 which inoculation concentration is 0.7g/L.The influent ammonia concentration was 50～500mg/L,aeration on 0.2L/min,dissolved oxygen(DO)on 0.1～4mg/L,temperature on 30～32℃,pH=7.2～7.4,hydraulic retention time(HRT)was 10h.After 63 days on operation,the ammonia nitrogen removal rate could reach to 80%or more,and total nitrogen removal rate could reach to 70%or more,nitrogen loading rate could reach to 1.42kg-N/m3/d,nitrogen removal rate could reach to 1.0kg-N/m3/d.(2)The concentration experiment started after a 900mg/L influent ammonia concentration was stable operation.Keep the water influent concentration between 80～140L/d,temperature on 30～32℃,pH=7.2～7.4,DO on 2～6mg/L,oxidation reduction potential was between 70～110mv.Then the ammonia concentration raised gradually to 2000mg/L for one month.The results showed that the nitrogen removal rate was maintained at 1.5～2.0kg-N/m3/d and total nitrogen removal rate could reach to 85%.However,the effluent was not stable due to reactor on the long-term and high load operation,two-stage SNAP reactor in series mode was considered to apply to the actual project.(3)The three temperature experiments conclude:the activity of anaerobic ammonium oxidation was the highest at 30℃ and the lowest at 10℃.Moreover,the removal rate of ammonia nitrogen showed a decreasing trend in the same temperature with the increase of the reactor nitrogen load.The ORP of three influent ammonia concentrations was analyzed,it could be obtained that when the influent ammonia concentration was 500mg/L and 1000m g/L,the ratio of the actual nitrate nitrogen and the theoretical nitrate nitrogen fluctuated at 1,but when the influent ammonia concentration was 2000mg/L,the ratio was almost all higher than 1,the highest reach to 2.3.It indicaed that with high ammonia concentration,the reactor aeration was relatively large promote the growth of nitrite oxidizing bacteria(NOB),so that a large number of nitrate accumulated.(4)The results on high throughput sequencing showed that the structure of microbial community was stable during start-up to stabilization in anaerobic ammonium oxidation reactor.Eight bacteria phylum were detected,and from the start to 2kg-N/m3/d high-load operation,Planctomycetes and Proteobacteria were the main bacteria phylum of which with denitrification function,respectively occupied 72.03%,78.60%and 52.42%in samples 1#,2#and 3#.The predominant bacteria specie was Candidatus Kuenenia which could withstand high Ammonia nitrogen concentration of Planctomycetes.The content of this kind of bacteria specie was about 40%in the upper part and the lower part of the reactor. |
PDF Full Text Request