To Select Anaerobic Process To Deal With Different C/N Wastewater And Reaserch Mechanism Of These Anaerobic Process

Industrial wastewaters always contain abundant refractory organic polymers and highorganic loads, which make that it is hard to achieve the desired treatment effect by singleaerobic biological treatment process. Anaerobic biotechnology is wide used in the treatmentof industrial wastewaters for its effectively degradation ability when treat high concentratedrefractory organic polymers,and low energy consumption. But traditional anaerobictechniques have the following three disadvantages:slow growth of anaerobic microorganismsresulted in the slow speed of start-up of the anaerobic reactor; hydrolysis acidification rate ofthe wastewater which has high concentration of refractory pollutants was slow,the processthat is propionic cid or butyric acid and so on converted to acetate had been affected byenvironmental factors easlly,because of excessive accumulation of ending acidic products inthis process which could take strong inhibition to the methanogens, leaded the anaerobicsystem to collapse; Anaerobic treatment have low nitrogen removal rate when the influentcontain high concentration nitrogen, often need addition of advanced treatment to removenitrogen after anaerobic treatment process,this resulted in longer wastewater treatment process,and much more investment and operating costs. This paper focuses on solves the threedisadvantages of the anaerobic treatment process, deal with different C/N wastewater as aresearch object, explore what is the best anaerobic process when treated different C/N ratioinfluent to achieve the following objectives: to avoid anaerobic reactor acidification and inorder to strengthen the anaerobic treatment effect;also achieve methanogenesis anddenitrification in a single reactor,in order to expand the anaerobic treatment field. Thisresearch mainly includes the following aspects: looking for some ways of quick start-up ofanaerobic reactor; explore the optimal anaerobic process to treat different C/N influent andstudy the mechanism.Low-intensity ultrasound could speed up the start-up process. The start-up of the ICanaerobic reactor by the granular sludge which had been treated by the low-intensityultrasound needed seven days, while the control group needed10days. Low-intensityultrasound increased COD removal efficiency of the IC anaerobic reactor, and made it withhigher gas production rate and the maximum methane-producing activity.There are different fermentation types under different C/N ratio,it found that when initialinfluent C/N ratio were12,56or156, acid-type fermentation can be found, when the initialinfluent C/N was200, ethanol-type fermentation can be found,these type fermentation caneffectively avoid the acidification of thedreactor,and there were the highest methane production rate and the effluent COD removal efficiency under ethanol-type fermentation;when the C/N ratio was56, the extracellular polymeric substances achieved maximum,different C/N ratio leaded characteristics of granular sludge surface to change, there had acertain impact on sludge settleability under different C/N ratio. Observed the culture ofanaerobic granular sludge which were under different C/N ratio from scanning electronmicroscope, found some changes taken place about the surface characteristics of microbialcommunities.Use IC anaerobic reactor and mature anaerobic granular sludge as seed sludge toacclimate sludge coupled with simultaneous methanogcnesis and denitrincation. glucose ascarbon source and sodium nitrate as nitrogen source of influent, COD/NO₃^-ratio was10, theinfluent carbon and nitrogen load were not changed and to gradually reduce the hydraulicretention time to domesticate anaerobic granular sludge, lasted30days to complete thedomestication, to achieved that IC anaerobic reactor coupled with simultaneousmethanogcnesis and denitrincation. In the experiment, the effluent COD removal efficiencywas more than95%,nitrogen removal efficiency was96%after25days; measured stableeffluent,found ammonia nitrogen which concentration was2mg/L, this anaerobic processbe called DNRA process; to detect the gas component, methane accounted for53%, nitrogenaccounted for47%. When COD/NO₃^-was2,4,8,10or16, the effluent COD removel ratioincreased first and then have a downward trend.When COD/NO₃^-was2, carbon source wasnot enough, the denitrification process had occurrenced, but methanogenesis was not befound, gas component was not detected methane; When COD/NO3–was4, COD removalefficiency was only84%; When COD/NO3–was8,10or16, COD removal rates were89%,95.1%,94.9%.When COD/NO3–was4,8or10,there was good removal efficiency ofnitrogen,acchived95%, When COD/NO3–was8,10or16,the enfluent was detected to theammonia nitrogen, this process was called DNRA process.Anaerobic granular sludge with simultaneous denitrification and producing methane hasobviously recovery function on the acidification caused by the propionic acid accumulation.When the acidification degree caused by the propionic acid were basic no acidification, mildacidification, moderate acidification and severe acidification, the COD removal rate of theanaerobic reaction bottle reached91.5%,87.9%,84.89%and81.05%, respectively. Wheneasing moderate and severe acidification, the best COD/NO₃^-values were8and6.