| Low-concentration methane is the main form of methane emission,which has the characteristics of low concentration,difficult to use and large displacement.For low-concentration methane treated by unorganized discharge,such as partial landfill gas and coal mine ventilation,biofilter（BF）can effectively reduce the environmental risk and greenhouse effect caused by low-concentration methane.In this paper,using the sources of landfill leachate were enrichment culture methane oxidation,use short-term training to get good start running non-biological packing of liquid oxygen biological filter,methane methane removal efficiency of biological filter and its influencing factors,on the basis of the concentration of the landfill methane on actual life biological filter has carried on the preliminary estimates and design.The research aims to optimize the short-term cultivation method of methane-oxidizing microorganisms,explore the BF start-up and influencing factors of pure abiotic filler,provide practical operational parameters of methane biofilters with engineering application value,enrich the selection of low-concentration methane biological treatment engineering,and provide reference for the application guidance of low-concentration methane emission reduction engineering.This paper mainly draws the following conclusions:（1）The vials batch culture test showed that landfill leachate could be used as the source of methanooxidizing bacteria.The cumulative methanooxidizing rate of 5 days showed that the culture effect of regulating pond leachate as the source of methanooxidizing bacteria was better than that of biochemical pond leachate.The optimum culture conditions were obtained from the Mixed Methanotrohic Consortia（MMCs）,in which the leachate was incubated at 37.5℃and the inoculation amount was 2/45.The maximum methane oxidation under the optimal conditions is 40.97 g CH4/（m3·d）.The continuous long-term culture experiment of vials lasted for 57 days,and the results showed that the stable methane oxidation effect could be maintained in a long time under the condition of ensuring the supply of nutrient elements in the culture system,and the long-term culture of bacterial liquid was feasible.（2）The methane oxidation biofilter can be effectively started by spraying the non-biological filler with the methanooxidizing bacteria liquid cultured for 2 days.The experimental results showed that the methane oxidation rate fluctuated obviously during the start-up process,and the maximum methane oxidation rate reached 25%during the 7th to 9th day,with an average methane oxidation rate of 6.56～7.06 g/（m3·h）.Biofilms produced during startup are pink or orange,and the effect of biofilm hanging is better in the area with stable bacterial fluid flowing through.The experimental results show that the methanooxidizing biofilter can be activated by adding the methanooxidizing bacterial solution of short-term culture.（3）Empty bed residence time（EBRT）is an important parameter affecting methane oxidation effect of biofilters.At 4.095 L BF filter bed volume,in different EBRT stages,when the EBRT is shortened from 178 min to 54 min,the average methane oxidation rates of each stage are 10.86,8.76,13.20,13.64 and 13.07 g/（m3·h）,respectively.The mean methane oxidation rate was 13.3±0.28 g/（m3·h）.The experimental results show that within the selected range of EBRT,the methane oxidation rate increases slightly with the shortening of EBRT.（4）The impact of impact load on methane oxidation effect of biofilter is simulated by increasing methane intake flow rate.The results show that the methane oxidation rate increases sharply to 26.18 g/（m3·h）during the impact load,BF turns to negative methane oxidation effect within 1.5 days after the impact load,and lasts for 2.5 days.Then part of the methane oxidation effect recovers,and the highest value is 11.94 g/（m3·h）.The mean value was 4.92 g/（m3·h）,lower than the normal 13.3±0.28 g/（m3·h）.According to the research results,although the impact load will reduce the methane oxidation rate of BF,BF has a certain tolerance to it.（5）Preliminary design of methane oxidation biofilter to escape landfill gas is carried out for actual domestic waste landfill site.For the sealed landfill with 58.4×104 t/a and 90%methane collection efficiency,the unorganized release flux of methane from landfill gas was estimated to be about 5.02 g/（m2·d）,and the BF volume of the designed landfill site was 20L/m2.When treating 100 m2 of unorganized landfill gas methane with BF with an inlet rate of 337.3 m3/h and methane oxidation rate of 13.3 g/（m3·h）,it is recommended that the site size of BF be 2 m3（1 mW×1 mL×2 mH）with 1.66 m3 of packing material. |
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