| With the increasing development of society and economy the nitrogen pollution in the wastewater ismore and more serious, while a large number of nitrogenous wastewater break the nitrogen cycle of natureand the harm can not be ignored. The nitrogen pollutants which comes from domestic waste water,industrial and agricultural wastewater is continuously increasing with the impovement of people’s livingstandard and the development of industry and agricutculture. NH+4-N is the main form of the nitrogenpollution has posed a great threat to human health and the environment. Faced with this situation, thedevelopment and application of cost-effective wastewater biological nitrogen removal technology is inurgent need.The integration of autotrophic denitrification is including two processes, nitrosification and anammox.Nitrosification means to accumulate NO2-by controlling operating conditions; anammox use the NO2-which is produced by nitrosification as electron acceptor, and transform the remaining NH+4into N2toachieve the purpose of removing nitrogen from water bodies. Compared with the traditional biologicaldenitrification process this process can save the vast majority of both oxygen consumption and energyconsumption, meanwhile it can reduce the operating costs and space, cut down the sludge production, ingeneral it has many advantages. The accumulation of NO2-is a key step in this experiment, and the core ofthe integration of autotrophic denitrification is anammox process.In this study, self-designed autotrophic denitrification reactor was used to start and recover theintegration of autotrophic denitrification reactor. And its influencing factors were studied when the reactoroperating stably. The main conclusions are as follows:(1) When water temperature was (33±1)℃, pH7.6-8.0, DO0.51mg/L-2.1mg/L, hydraulic retentiontime (HRT) maintained7h, the reactor run143d and finally start-up successfully. The self-designedautotrophic denitrification reactor was inoculated with anammox bacteria, after143d of acclimatizationtraining in three phases, controlling the operating conditions of the reactor with proper commissioning thereactor eventually started successfully. When the reactor operating stably, the ammonia removal rate reach more than80%, and the total nitrogen removal rate up to66%at the same time. In addition, the nitrogenremoval load of the reactor top to0.28kg/m3d.(2) The integration of autotrophic denitrification reactor was stopped for about two months, but thereactor can recover it’s activity after two stages with low loading rate of18days recovery training. Thesuccessful started integration reactor was using low concentrations strategy for recovery and thetemperature was controlled at33±1℃, the pH was adjusted to7.8to8.0, HRT maintained at5h. Underthis situation the reactor restored stability fast and NH+4-N, TN can reach high removal rate, ammoniaremoval rate can reach97%and total nitrogen removal rate steady at70%.(3) Operating characteristics. In this study, with the study of the operating characteristics of theintegration of autotrophic denitrification reactor， that the optimal dissolved oxygen range to operate thereactor is2mg/L to3mg/L and the optimum hydraulic retention time is5h is confirmed，as well as theinfluence of organic matter on the reactor operation process and the recovery rate.Influent DO concentration will affect the effect of the integration of denitrification reactor either toohigh or too low. When DO concentration is too low, the degree of nitrification will not be enough, resultingin insufficient anammox electron acceptor and poor nitrogen removal. When DO concentration is too high,nitrifying bacteria grows superior to the nitrification bacteria and most influent ammonia is converted tonitrate, resulting in inhibition of anammox reaction and a too high effluent nitrate nitrogen content. Thus,the ammonia and total nitrogen removal were substantially reduced.The impact from COD to reactor showed that a small amount of organic matter in the water performsnot much influence on the activity of bacteria, and a lot of organic matter will cause changes in thedominant species in the reactor, thereby undermining the effective composition of flora of the integration ofdenitrification reactor, which will cause that nitrogen removal significantly deteriorated. When COD reachs150mg/L, denitrification reactor loses activity. Under the condition of zero COD, the reaction rate can be5%/d to recover denitrogenation effect.The nitrogen removal effect of the integration of autotrophic denitrification reactor will vary withchanges in the fluctuation of HRT.If HRT is too long, it will promote the growth and reproduction ofnitrifying bacteria, resulting in the inhibition of nitrification bacteria, but too short HRT would lead tounfavorablity for anammox bacteria to survive beccause the era period of anammox bacteria is relatively long. Therefore,5h is the best HRT, when the reactor operates normally with ammonia removal efficiencyreaching80%and total nitrogen removal rate over70%... |
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