| With the increasing amount of waste disposal in China's landfills,the odors released by the decomposition of waste organic matters lead to NIMBY?Not In My Back Yard?,which hinders the normal construction and operation of MSW?Municipal Solid Waste?disposal facilities.As a kind of disorganized air pollution source,the traditional physical-chemical or biological deodorization methods are no longer applicable for landfill odors.In this work,a simple,low-cost,efficient and stable in-situ deodorization technology for landfill odors was discussed,i.e.,a new type of functional covering layer for landfills was prepared by combining physical-chemical adsorption and biodegradation to remove the odors in situ.The main conclusions are as follows:?1?The functional covering material prepared from aged refuse and sludge carbon with a certain material mass ratio and water content had a significant physical-chemical adsorption effect both on individual and mixed odors.In the adsorption experiments of individual odor,the maximum absolute removal amount of NH3,H2S and toluene can reach1.39×10-5,6.33×10-6 and 4.88×10-6 mg/g,respectively.There was no obvious synergistic inhibition in the physical-chemical adsorption of mixed odors,and the maximum absolute removal amount of NH3,H2S and toluene can reach 1.42×10-5,8.08×10-6 and 4.42×10-6 mg/g,respectively.?2?Microbes from aged refuse?AR?,composting?CP?,anaerobic sludge?AS?and sludge based carbon?SC?were screened and domesticated to improve the removal efficiency and stability of biodegradation process.Results showed the reduction of theory odor concentration were 24%,40%,70%and 58%in terms of CP,SC,AR and AS,respectively.In the best-performing MC-AR,the biodegradation amount of NH3,H2S and toluene were 4.84×10-5,3.72×10-5 and 0.80×10-5 mg/mL.If only the individual odors were considered in MC-AR,the higher biodegradation amount of8.32×10-5,6.38×10-5 and 2.00×10-5 mg/mL in terms of NH3,H2S and toluene were obtained,respectively.There was an obvious competitive inhibition effect among the components of mixed odors.?3?Through the analysis of liquid phase metabolites in MC-AR,the possible transformation pathways of three odors were proposed,namely NH3 was converted into NH4+and NO3-,H2S was biodegraded as S and SO42-,and toluene was decomposed as CO2.Pseudomonas was found to be higher in contents with the value of 42.53%,and after 24 h odors biodegradation the dominant species changed to Burkholderia with the relative abundance of 34.43%.?4?The functional covering layer was prepared by mixing the covering materials with the microbial liquid with the mass ratio of 4:1.It was found that the removal rate of each gas was negatively correlated with inlet gas concentration and temperature,and positively correlated with the thickness of covering layer.The removal rate of NH3,H2S and toluenen were 96.48%,87.60%and 91.57%,respectively,when the thickness of covering layer was 60 cm and the temperature was 40?with the inlet gas concentration of 25,10 and 0.10 mg/m3.?5?The microbial community structure changed obviously before and after column experiments,and the microbial diversity in covering soil was significantly increased by the introduction of odors.The microorganisms with relatively high contents in the covering soil were Thiobacillus,Acidobacteria,Bacillus and Pseudomonas,etc.And the relative abundance of Thiobacillus increased from 11.90%to 26.77%after the introduction of odors. |
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