Operation Characteristics Of Microbubble-aerated Biological Fluidized Bed Reactor

Microbubbles are usually tiny bubbles with a diameter of less than 50 ?m.Microbubble aeration technology has higher gas-liquid mass transfer efficiency compared with the traditional aeration method,and has the potential application advantage in wastewater treatment.Aerobic biological fluidized bed has the characteristics of high biological activity,good mass transfer and high treatment efficiency.The SPG membrane microbubble aerated biological fluidized bed reactor was used for the treatment of simulated domestic wastewater in this study.The carriers used in the microbubble aeration biological fluidized bed reactor were compared.The effects of organic loading and nitrogen load on the performance of microbubble aeration biological fluidized bed reactor were investigated.The results show that under the same conditions,the carbon fiber carrier had better performance.The COD removal rate and the removal load tends to be stable at 20 d in the biological fluidized bed reactor filled with carbon fiber carrier,and the corresponding t removal rate and the removal load were 90% and 0.75 kg/(m3.d).The removal rate and removal load of ammonia nitrogen were 35% and 0.11 kg/(m3.d),respectively.The biofilm growth rate of the biological fluidized bed filled with carbon fiber filler was faster,and the biomass was stable at 0.90 g/L after 20 d.During the operation of microbubble aeration biological fluidized bed reactor with carbon fiber carrier,DO concentration decreased with the increase of organic loading,but the pollutant removal efficiency changed little.The removal rate of COD was stable at about 80%,and the removal load was as high as 3.53 kg/(m3.d).The removal rates of ammonia nitrogen and TN were 45% and 43%,respectively.The nitrogen removal was inefficient because of high organic loading,low DO concentration and the longer time of nitrification bacteria formation.The total activity of biofilm,aerobic activity and nitrification activity decreased continuously with the increase of organic loading.There was no change in the composition of extracellular polymeric substances,but the content was changed.With the increasing of nitrogen loading,DO concentration decreased,but COD removal efficiency was stable.The removal rate and the removal load were 85% and 0.85 kg/(m3.d).The ammonia nitrogen and TN removal rate decreased,but both removal load gradually increased up to 0.09 kg/(m3.d).The nitrogen mainly removed by simultaneous nitrification and denitrification process when DO concentration was high.In addition,the nitrogen mainly removed by short-cut nitrification and denitrification.The aerobic decomposition activity of biofilm was good and stable,the activity of ammonia oxidation increased,and the activity of nitrite decreased gradually.There was no change in the composition of extracellular polymeric substances,but the content was changed.