Study On Optimization And Application Of Biocarriers For AoB And AnAoB In MBBR Process

Due to its low energy consumption and high treatment efficiency,combined with no demand of external organic carbon,autotrophic nitrogen removal process has a great application prospect.Serious sludge loss and long startup time exist in the operation of autotrophic nitrogen removal process.In this study,the biofilm formation experiments of various commercial biocarriers were carried out.Biocarriers suitable for biofilm formation of ammonia-oxidizing bacteria and anaerobic ammonium-oxidizing bacteria were separately screened out.It could provide a technical reference for the selection of biocarriers in the engineering application of autotrophic nitrogen removal process.After that,coagulation-anaerobic digestion-ammonia oxidation?MBBR?-anaerobic ammonium oxidation?denitrification,MBBR?process was used in treating municipal sludge plate-and-frame press filtrate,and the operation effect of this process was analyzed.That could provide reference experience for engineering application.The main results and conclusions are as follows:?1?The conversion efficiency of NH₄⁺-N in the reactor of ammonia-oxidizing bacteria was improved obviously after adding biocarriers.When hydraulic retention time was 0.5 days and the concentration of NH₄⁺-N in the influent of the reactor was 600-700 mg/L,the conversion efficiency of NH₄⁺-N could be stabilized between 52%and 61%.Nitrosomonas was the genus of ammonia-oxidizing bacteria.AQ1 polyurethane cubic biocarrier was the most suitable biocarrier for biofilm formation by this ammonia-oxidizing bacteria.The ammonia oxidation rate of matured biofilm was 0.81±0.08 mg N/?L·h?and the biofilm biomass was 0.87±0.14 mg VSS.For AQ1 biocarrier,the effect of biofilm formation by ammonia-oxidizing bacteria was similar to that by anaerobic ammonium-oxidizing bacteria.?2?The total nitrogen removal efficiency of anaerobic ammonium-oxidizing bacteria reactor was greatly improved after adding biocarriers.When the hydraulic residence time was0.5 days and the total nitrogen concentration in the reactor influent was 600-700 mg/L,the total nitrogen removal efficiency of the reactor could be stabilized between 86%and 91%.The genus of anaerobic ammonium-oxidizing bacteria was Candidatus Kuenenia.K3 annular biocarrier?made of polyethylene or polypropylene?was the most suitable biocarrier for the formation of biofilm by this anaerobic ammonium-oxidizing bacteria.The anaerobic ammonium oxidation rate of matured biofilm could reach 3.27±0.10 mg N/?L·h?,and the biofilm biomass was 2.74±0.40 mg VSS.For K3 biocarrier,the effect of biofilm formation by anaerobic ammonium-oxidizing bacteria was better than that by ammonia-oxidizing bacteria.The reason was that the content of extracellular polymeric substances secreted by anaerobic ammonium-oxidizing bacteria was higher than that of ammonia-oxidizing bacteria,and extracellular polymeric substances play an important role in biofilm formation.?3?The effluent of municipal sludge plate-and-frame press filtrate treated by coagulation-anaerobic digestion-ammonia oxidation?MBBR?-anaerobic ammonium oxidation?denitrification,MBBR?process could meet the requirements of the relevant standards.Among them,the equivalent FeCl₃ dosage of the wastewater coagulation was 200 mg/L,the maximum COD removal rate of anaerobic digestion EGSB reactor could reach 3.94 kg COD m^-3d^-1,and the maximum nitrogen removal rate of the ammonia oxidation-anaerobic ammonium oxidation?denitrification?MBBR could reach 0.25 kg N m^-3d^-1.