生物炭填埋场土壤覆盖层的甲烷减排性能和生物特征

覆盖土的组分与甲烷生物氧化潜力效率密切相关.将水稻秸秆生物炭与填埋场覆盖层土壤以一定的比例混合后填充入覆盖层模拟柱,形成生物炭土壤覆盖层模拟柱(RB),同时设置土壤覆盖层模拟柱(RS)为对照组,考察生物炭的添加对覆盖层的甲烷减排性能和生物特征的影响.结果表明:RB的甲烷减排性能提升较快,第81d时进气中99%的甲烷已被去除,RS在第95d时才达到99.16%的甲烷减排率;RS上、中、下3层的优势甲烷氧化细菌(MOB)为Methylocaldum,而RB的上层和中层为Methylobacter,下层则为Methylocaldum.至试验末期时,RS在上、中、下3层的总MOB相对丰度分别为9.05%、5.95%和42.12%,RB则分别为50.81%、42.67%和31.41%.同时在RS和RB中均检测出厌氧甲烷氧化古菌.由此表明生物炭的添加改变了填埋场土壤覆盖层的菌属分布,促进了MOB的生长,提高了甲烷减排性能.

Methane emission reduction and biological characteristics induced by the landfill cover soil amended with biochar

The components of cover soil are closely associated with the methane bio-oxident potential efficiency. Therefore, a landfill cover soil amended with biochar (RB) with a conventional cover soil(RS) as a control, was designed to investigate the influences on the CH₄ mitigation potential as well as the microbial characteristics in this work. The results indicated that the addition of the biochar into the soil enabled to facilitate the CH₄ mitigation potential. Notably, about 99.00% of the methane in the inlet of RB was removed on the 81th day, while the methane reduction rate of RS reached 99.16% on the 95th day. Furthermore, the methane-oxidizing bacteria (MOB), Methylocaldum was observed dominantly in all the layers of the RS, while Methylobacter was dominant in the upper and middle layers of RB and Methylocaldum in the lower layer. The corresponding abundances of the total MOB were 9.05%, 5.95% and 42.12% in the upper, middle and lower layers of RS, respectively, and 50.81%, 42.67% and 31.41% in the RB, respectively. In brief, biochar amended in the bio-cover undoubtedly improve the methane emission reduction performance through the acceleration of the growth of MOB and optimizing the distribution of bacteria in the landfill cover layer.