有机硅胶载体影响纤维素厌氧消化产甲烷潜能研究

Effects of Organic Silica Gel on Methane Production Potential of Cellulose through Anaerobic Digestion

摘要:

在厌氧消化体系中投加载体,能为厌氧微生物提供空间结构和物质基础,进而促进微生物定向增殖与群落生态稳定,提升产沼气潜力。然而,在选择新型载体材料时,需先评估其毒性影响对产甲烷过程的潜在抑制作用。本研究通过分批补料发酵模式,考察了AB硅胶5种不同添加量(2%、5%、10%、15%、20% )对纤维素降解产甲烷过程的影响,以评估该AB硅胶作为载体材料的可行性。结果表明,添加AB硅胶导致CH4产量显著降低,其中2%的添加量对产甲烷的抑制作用最强,3轮试验中累积CH4产量降幅分别达41.3%、31.8%、31.1%。优势水解细菌Bacillota(厚壁菌门)的相对丰度从69.7%下降至57.9% ,Synergistota(互养菌门)的相对丰度从10.8%增加至15.7% ,Methanosarcina(甲烷八叠球菌属)和Methanoculleus(甲烷袋状菌属)的相对丰度分别从15.4%和2.4%下降至10.0%和1.4%。不同于典型的化学抑制,试验过程中并未观测到末期挥发性脂肪酸的积累和pH值的失稳,表明抑制作用可能并非源于产甲烷菌群的中毒,而可能因为有机硅胶填充了部分体积,阻碍了微生物与纤维素的接触,导致部分纤维素未被降解。采用3轮试验结束后的剩余发酵液进行比产甲烷活性测试,结果显示,AB硅胶对发酵液比产甲烷活性的半抑制浓度(IC50)为1.8% ,该临界浓度为AB硅胶载体投加阈值设计提供参考。

Abstract:

The addition of carriers to anaerobic digestion (AD) systems to provide spatial structures and colonization sites for microorganisms, thereby enhancing community stability and biogas potential, is a focal point of current research. However, when selecting novel carrier materials, it is imperative to first evaluate their toxicological impacts and potential inhibitory effects on the methanogenic process. Through a fed-batch fermentation mode, the effects of AB silicone at five different dosage concentrations (2% , 5% , 10% , 15% , and 20%) on the cellulose degradation and methanogenesis process were investigated, to evaluate the feasibility of utilizing this AB silicone as a carrier material. The results demonstrated that the addition of AB silicone led to a significant decrease in the CH4 yield, with the 2% dosage exhibiting the most pronounced inhibitory effect on methanogenesis. Across the three consecutive experimental rounds, the cumulative CH4 production was decreased by 41.3% , 31.8% , and 31.1% , respectively. The relative abundance of the dominant hydrolytic bacteria Bacillota (Firmicutes) was decreased from 69.7% to 57.9% , whereas that of Synergistota was increased from 10.8% to 15.7%. Furthermore, the relative abundances of Methanosarcina and Methanoculleus declined from 15.4% and 2.4% to 10.0% and 1.4%, respectively. Distinct from typical chemical inhibition, neither terminal accumulation of volatile fatty acids (VFAs) nor pH instability was observed during the experiment, indicating that the inhibitory effect likely did not stem from toxicity to the methanogenic consortia, but possibly because the organic silicone filled a portion of the volume, hindering the contact between microorganisms and cellulose, which led to a portion of the cellulose remaining undegraded. Specific methanogenic activity ( SMA) assays conducted on the residual fermentation digestate after the three rounds of experiments revealed that the half-maximal inhibitory concentration (IC50) of AB silicone on the SMA was 1.8%.