Xu Jie, Lin Hongjian, Sheng Kuichuan
School of City and Architecture Engineering, Zaozhuang University, Zaozhuang, China.
College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, China.
Front Microbiol. 2021 Apr 12;12:622235. doi: 10.3389/fmicb.2021.622235. eCollection 2021.
Proper disposal and utilization of dead pig carcasses are problems of public concern. The combination of hydrothermal pretreatment (HTP) and anaerobic digestion is a promising method to treat these wastes, provided that digestion inhibition is reduced. For this reason, the aim of this work was to investigate the optimal HTP temperature (140-180°C) for biogas production during anaerobic digestion of dead pigs in batch systems. In addition, the effects of hydrochar addition (6 g/L) on anaerobic digestion of pork products after HTP in continuous stirred tank reactors (CSTR) were determined. According to the results, 90% of lipids and 10% of proteins present in the pork were decomposed by HTP. In addition, the highest chemical oxygen demand (COD) concentration in liquid products (LP) reached 192.6 g/L, and it was obtained after 170°C HTP. The biogas potential from the solid residue (SR) and LP was up to 478 mL/g-VS and 398 mL/g-COD, respectively. A temperature of 170°C was suitable for pork HTP, which promoted the practical biogas yield because of the synergistic effect between proteins and lipids. Ammonia inhibition was reduced by the addition of hydrochar to the CSTR during co-digestion of SR and LP, maximum ammonia concentration tolerated by methanogens increased from 2.68 to 3.38 g/L. This improved total biogas yield and degradation rate of substrates, reaching values of 28.62 and 36.06%, respectively. The acetate content in volatile fatty acids (VFA) may be used as an index that reflects the degree of methanogenesis of the system. The results of the present work may also provide guidance for the digestion of feedstock with high protein and lipid content.
病死猪尸体的妥善处置和利用是公众关注的问题。热预处理（HTP）与厌氧消化相结合是处理这些废弃物的一种很有前景的方法，前提是减少消化抑制。因此，本研究的目的是在间歇系统中研究病死猪厌氧消化过程中产生沼气的最佳HTP温度（140 - 180°C）。此外，还测定了在连续搅拌釜式反应器（CSTR）中添加水热炭（6 g/L）对HTP后猪肉产品厌氧消化的影响。结果表明，HTP分解了猪肉中90%的脂质和10%的蛋白质。此外，液体产物（LP）中最高化学需氧量（COD）浓度达到192.6 g/L，这是在170°C HTP后获得的。固体残渣（SR）和LP的沼气潜力分别高达478 mL/g-VS和398 mL/g-COD。170°C的温度适合猪肉的HTP，由于蛋白质和脂质之间的协同作用，促进了实际沼气产量。在SR和LP共消化过程中，向CSTR中添加水热炭可降低氨抑制，产甲烷菌耐受的最大氨浓度从2.68 g/L提高到3.38 g/L。这提高了底物的总沼气产量和降解率，分别达到28.62%和36.06%。挥发性脂肪酸（VFA）中的乙酸含量可作为反映系统甲烷生成程度的指标。本研究结果也可为高蛋白和脂质含量原料的消化提供指导。
