Simultaneous biomethanisation of endogenous and imported CO2 in organically loaded anaerobic digesters
Simultaneous biomethanisation of endogenous and imported CO2 in organically loaded anaerobic digesters
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DOI：
10.1016/j.apenergy.2019.04.058
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发表时间：
2019-08
期刊：
影响因子：
11.2
通讯作者：
Bing Tao;Anna M. Alessi;Yue Zhang;J. Chong;S. Heaven;C. Banks
中科院分区：
文献类型：
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作者：
Bing Tao;Anna M. Alessi;Yue Zhang;J. Chong;S. Heaven;C. Banks
原位生物甲烷化通过直接向厌氧消化池注入H_2将沼气中的CO_2减少为CH_4，但体积甲烷产量(VMP)受到有机负荷的限制。异地生物甲基化，即将气体底物喂入纯或混合的产氢产甲烷菌培养物中，可提供更高的VMP，但需要额外的反应器和必需养分的供应。这项工作在一种新的混合应用中结合了这两种方法，实现了在接受补充沼气的有机负荷厌氧消化池中同时进行原位和非原位生物甲基化。传统的搅拌式沼气池首先对添加H_2进行驯化，沼气甲烷含量从50%提高到95%，VMP从0.86提高到1.51 L L−1天−1，中等负荷3 g有机物需氧量/L每天(g CODorgL−1天−1)。然后加入外部生产的沼气，以演示内源和进口二氧化碳的同时生物甲基化。这在不影响有机底物降解的情况下，进一步提高了VMP值至2.76VMP L L−1day−1。CO2的原位还原可以通过减少碳酸氢盐的缓冲来改变消化池的pH：组合工艺在pH 8.0左右、顶空CO2含量为3~5%时稳定运行。微生物群落分析表明，这一过程是由细菌合养醋酸酯氧化和高度丰富的水基因营养产甲烷古菌(高达97%的古菌种群)介导的。这一办法提供了改造单一沼气池以供注氢的机会，以从其他几个沼气池转换和升级沼气，通过利用现有基础设施和废物衍生的原料养分同时进行沼气升级和沼气发电，最大限度地减少资本和运营成本。
In-situ biomethanisation reduces the CO2in biogas to CH4via direct H2injection into an anaerobic digester, but volumetric methane production (VMP) is limited by organic loading. Ex-situ biomethanisation, where gaseous substrates are fed to pure or mixed cultures of hydrogenotrophic methanogens, offers higher VMP but requires an additional reactor and supply of essential nutrients. This work combined the two approaches in a novel hybrid application achieving simultaneous in-situ and ex-situ biomethanisation within an organically-loaded anaerobic digester receiving supplementary biogas. Conventional stirred-tank digesters were first acclimated to H2addition, increasing biogas methane content from 50% to 95% and VMP from 0.86 to 1.51 L L−1day−1at a moderate loading rate of 3 g organic chemical oxygen demand per L per day (g CODorgL−1day−1). Externally-produced biogas was then added to demonstrate simultaneous biomethanisation of endogenous and imported CO2. This further increased VMP to 2.76 L L−1day−1without affecting organic substrate degradation. In-situ CO2reduction can alter digester pH by reducing bicarbonate buffering: the combined process operated stably at around pH 8.0 with 3–5% CO2in the headspace. Microbial community analysis indicated the process was mediated by bacterial syntrophic acetate oxidation and highly enriched hydrogenotrophic methanogenic archaea (up to 97% of the archaeal population). This approach presents the opportunity to retrofit a single digester for H2injection to convert and upgrade biogas from several others, minimising capital and operating costs by utilising both existing infrastructure and waste-derived feedstock nutrients for simultaneous biogas upgrading and power-to-methane.