硫化氢对填埋场生物炭改性覆土的甲烷氧化的影响

填埋场覆土中甲烷氧化菌的生物氧化作用,是填埋场CH4最主要的自然减排途径,但通常传统的覆土材料CH4氧化能力并不足.生物炭可用于强化填埋场覆土的CH4氧化性能,同时,填埋气中的硫化氢(H2S)也易被生物炭吸附转化,可能为CH4氧化带来潜在影响,需要进一步探究和揭示.在前期实验基础上,设计了一种生物炭改性覆土材料,接种富...

EFFECT OF HYDROGEN SUFIDE ON METHANE OXIDATION OF BIOCHAR-AMENDED LANDFILL COVER SOIL

Biological oxidation of methane(CH₄) by CH₄-oxidizing bacteria in landfill cover soil(LCS) is the most important natural way to reduce CH₄ emission at landfills; however, the CH₄ oxidation capacity of the traditional LCS is usually insufficient. Studies showed that biochar can be used to enhance the CH₄ oxidation performance of LCS. Simultaneously, biochar also presents good adsorption and conversion of hydrogen sulfide(H₂S) in landfill gas, owning potential impact on CH₄ oxidation, which needs to be further investigated and revealed. Based on previous experiments, this study designed and adopted a biochar-amended LCS, inoculated it with enriched methane-oxidizing bacteria solution, and then carried out four-cycle CH₄ oxidation incubation experiments under four H₂S concentration conditions(0, 0.01%, 0.025% and 0.1% by volume). The results showed that as H₂S concentration increased, the CH₄ oxidation capacity first decreased, then increased, and finally decreased. Under 0.01% H₂S, CH₄ oxidation decreased slightly by 11.5%; while under 0.025% H₂S, CH₄ oxidation increased by 17.0%. However, 0.1% H₂S obviously inhibited CH₄ oxidation and reduced it by 28.8%. Combining the results of CH₄ oxidation and the changes in the physical and chemical properties of the soil, it was inferred that the increase of CH₄ oxidation capacity was attributed to the positive stimulation of methane monooxygenase at a low concentration of H₂S around 0.025%. While high H₂S concentration exhibited a significant inhibition of CH₄ oxidation, due to its microbial toxicity and possible oxygen competition during the adsorption and oxidation process.