Study On Under Normal Temperature Pnematic UASB Reactor Processing City Life Sewage Performance

With the rapid development of industry and agriculture in our country and theincrease of population, the shortage of resources and energy become more and moreserious. The degradation of water environmental and the shortage of energy havebecome the two major problems which restrict the continuous development of ourcountry.As the wastewater treatment technology which not only save energy but alsoproduce energy, anaerobic biological treatment technology provides a effective waywhich conform to the principles of continuous development. The experiment whichcombined with the advantages and disadvantages of UASB reactor researched thepneumatic UASB reactor. The advantages of reactors include that as follows: shortstart-up time under normal temperature; low financial investment; low processingcosts, well adaptability to the fluctuations of the concentration of COD_Cr; high gasproduction, and so on.It is suitable for the applicable to the low-cost small townswhich have low water quality requirements and irrigated.The article research the pneumatic UASB reactor which adopted the biogasgenerated from the circulation to finish stirring. The mass transfer efficiency and theability of stirring are much better than the ordinary UASB reactor.The experiment use the sewage of Qingdao technological university, and theexperiment lasts for126days. It studies include in under the room temperatureconditions,the treatment efficiency of the pneumatic UASB reactor on the lowconcentration sewage of the city; the influence of Temperature, pH value, VFA value,volume load （VLR）, and other technological conditions on the pneumatic UASBoperation condition, which concluded the best process conditions that UASB reactordeal with the low concentration city life sewage; the sewage treatment efficiencyinfluence of change the mode of agitation （every day start the pump three times, andeach lasts30minutes）; when the Volume Load reach5.0kgCOD_Cr/（m³·d）, thencontinue increase the load, study the maximum volume load of this reactor;meanwhile ammonia nitrogen removal efficiency and the morphology of sludge were studied in this paper.The results of experiments are listed as follows:1. The time of reactor which start-up under normal temperature use only51d,far more than the ordinary UASB start-up time （ordinary UASB reactor is commonly3⁶months）. The main reason is that the reactor sludge bed area has the high gasrising velocity which not only have a good selection to the sludge, but also improvethe mass transfer efficiency between the sewage and sludge.2. The system which runs stably have a good adaptability to the sewage COD_Crconcentrations fluctuate good adaptability. When the reactor stability in5.0kgCOD_Cr/（m³·d）, the concentration of sewage from³36to808mg/L, the COD_Crconcentration of the treated water keep in120mg/L,and the water COD_Crremovalrate steady at80%or more.3. The effect of COD_Crremoval is good. When the Volume Load reached5.0kgCOD_Cr/（m³·d）, the COD_Crremoval rate of low concentration sewage at more than80%,the COD_Crconcentration of the treated water keep in120mg/L.To a simpleanaerobic treatment system, from the test result we can see that, the treatment effectof COD_Cris well.4. The effluent ammonia nitrogen （NH+4-N） of the reactor is larger than water,and the COD_Crconcentration of the system effluent is low. The anaerobic reactors hasa good effect on killing the viral microorganisms, and the effluent in line with therural irrigation water requirements.5. In the treatment of sanitary sewage does not exist the factor of addingalkalinity which has a strong influence on the process of treat with high concentrationof wastewater. This is because the sewage has a low concentration, and produces lessVFA, in general, the effluent VFA in450mg/L or less.At the same time because thematrix has a good biochemical conversion, the converted VFA can immediately betransformed into biogas, emissions to the outside world.So the VFA which can causepH lower is not enough to overcome the original pH buffer system which had existed.to ensure the pH of the water stability.