气体循环方式对餐厨废水厌氧消化沼气生物提纯的影响

Effects of gas recirculation mode on biogas biological upgrading by anaerobic digestion of kitchen wastewater

本研究对餐厨废水进行厌氧消化处理,并利用纳米零价铁供氢及嗜氢产甲烷菌的代谢作用来提高CH_(4)含量,以实现沼气异位生物提纯。实验中比较了单向式、往复式、循环式3种气体循环方式对厌氧消化-沼气提纯耦合系统的影响。结果表明:3种气体循环方式均可提高CH_(4)含量,其中循环式可获得最大甲烷含量为93.87%,累积沼气(CH_(4))产量为167.44(157.18)mL·g^(-1)(以VS计);纳米零价铁可降低沼气提纯体系内ORP,气体循环促进了COD和VFAs的降解,CO_(2)循环有利于维持体系内酸碱平衡,富氢值表明H_(2)传质效率显著提高。微生物群落结构分析结果表明,产甲烷菌类型已向氢营养型产甲烷菌演替,Methanobacterium和Methanolinea相对丰度最大。以上研究结果表明,基于纳米零价铁供氢的沼气异位提纯和气体循环可以提升厌氧消化性能,提高CH_(4)含量。

In this study,the anaerobic digestion was used to treat the kitchen wastewater,and the CH_(4) content increased through the combined way of hydrogen supplied from nano zero-valent iron(nZVI)dissolution and metabolism effect of hydrogenotrophic methanogens,the ex-situ biological upgrading of biogas was achieved.The effect of three gas recirculation modes named one-direction-flow,reciprocating-flow and circulating-flow on the anaerobic digestion-biogas biological upgrading systems were compared in this experiment.The results showed that all three gas recirculation modes could increase CH_(4) content,of which circulating-flow mode could produce the maximum methane content of 93.87%,the corresponding cumulative biogas(CH_(4))yield was 167.44(157.18)mL·g^(-1)(VS basis).nZVI addition could decrease the ORP in biogas upgrading system,gas recirculation promoted the degradation of COD and VFAs,CO_(2) recirculation maintained the balance of acidbase,the value of hydrogen enrichment indicated that the mass transfer efficiency of H2 increased significantly.The microbial community analysis showed that the methanogenic microorganisms transformed to hydrogenotrophic methanogens,in which the highest relative abundances were Methanobacterium and Methanolinea.The above results indicated that based on the hydrogen supply by nZVI method,the biogas exsitu biological upgrading and gas recirculation could improve the anaerobic digestion performance and CH_(4) content.