Fixing collapsed dry anaerobic digestion system of kitchen waste caused by severe VFAs accumulation

Jiongke Wang, Xiaoyu Tang, Hongnan Yang, Qi Zhao, Heng Wang, Liangwei Deng and Wenguo Wang

Renewable Energy, 2024, vol. 237, issue PA

Abstract: Severe inhibition by volatile fatty acids (VFAs) frequently occurs during the dry anaerobic digestion of kitchen waste at high organic load rate (OLR), leading to decreased biogas production and even the collapse of the anaerobic digestion system. In this study, VFAs accumulation was significantly reduced by adding powder-activated carbon (PAC) or alkaline additives (AA), thus restoring the collapsed system to a stable operating state. With the addition of PAC or AA, the maximal OLR reached 11.14 g VS/(L·d), which was 30 % higher than observed without any additives (control group), while the VFAs concentration was maintained below 3000 mg/L. At this OLR, the volumetric biogas production rate stabilized at 5.1 L/(L·d) in the presence of PAC and AA, while that of the control group gradually decreased to zero. The VFAs concentration with PAC addition was 86 % lower than that of the control group, possibly because PAC might stimulate the formation of direct interspecies electron transfer between syntrophic bacteria and methanogens (Methanosarcina), thereby promoting VFAs degradation. The addition of AA, which resulted in a 95 % decrease in ammonia-nitrogen concentration, can provide a good growth environment for the microorganisms involved in acidogenesis and hydrogenotrophic methanogenesis.

Keywords: Organic load rate; Volatile fatty acids; Ammonia inhibition; Direct interspecies electron transfer (search for similar items in EconPapers)
Date: 2024
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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:237:y:2024:i:pa:s0960148124016574

DOI: 10.1016/j.renene.2024.121589

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