为研究木质生物炭对厌氧发酵产甲烷性能的影响,以玉米秸秆、牛粪作为发酵底物,以灌木生物炭、杨木生物炭、混合木屑生物炭作为添加剂,通过控制生物炭的种类、粒径以及灰分含量等关键因素,进行了批式厌氧发酵强化试验.结果表明:生物炭对厌氧发酵系统有重要影响,且粒径越小,产气能力越强.其中,杨木生物炭对厌氧发酵系统影响最大,不仅提升了厌氧发酵系统的甲烷累积产量(4.9％)、最大甲烷日产率(15.0％)以及水解速率(15.6％),也缩短了发酵延滞期.此外,杨木生物炭的灰分含量对厌氧发酵也有重要影响.当灰分含量为2.6 g·L-1时,对厌氧发酵系统影响最大,在提升厌氧发酵系统的缓冲能力、最大甲烷日产率(14.4％)的同时,也缩短了延滞期(11.8％),灰分含量过高或过低均不利于系统产甲烷.

利用AMPTS全自动甲烷潜力测试系统、First-Order水解模型、修正的Gompertz 和logistic模型,在了解生物炭各理化特性的基础上,通过对厌氧发酵的水解速率、产甲烷潜力及最大甲烷产率等进行拟合和对比分析,研究木屑生物炭对序批式湿法厌氧发酵的影响规律.结果表明:木屑生物炭对序批式厌氧发酵前期的底物水解速率、甲烷产率及累积甲烷产量均有着显著的影响,其中木屑生物炭对水解速率的影响强于果木生物炭和活性炭,较椰壳生物炭弱,且提升厌氧发酵系统的缓冲能力较椰壳生物炭和活性炭强.木屑生物炭对厌氧发酵的强化作用与生物炭粒径成负相关,当粒径＜0.5 mm 时强化效果最好,提高水解速率33.93％,提升最大产甲烷速率约19.32％,缩短延滞期约51.28％.

Microbial electrolysis cell (MEC) has emerged as the promising technology for COD removal as well as bioenergy recovery during the treatment of bio-refractory wastewaters. This study mainly focused on wood vinegar (the by-product from biomass pyrolysis) treatment via MEC technology with two typical biochars (coconut shell biochar and shrub biochar) as the carriers of microorganisms in anode chamber. Results indicated that MECs with coconut shell biochar had an obvious beneficial effect for treating wood vinegar, with COD removal reached up to 71.4%. GC-MS analysis showed that furfurals present in the wood vinegar were thoroughly degraded after MEC treatment. One interesting finding is that hydrocarbons accounted for a large portion of the compounds in the effluent, which may be the comprehensive result of complex organic reactions, including decarboxylation reactions, dehydration reaction, etc. The dominant microbial populations in MEC with biochar anode mainly included Geobacter, Macellibacteroides, Oscillibacter, Sedimentibacter, Comamonas, and Lachnoclostridium. This study demonstrated that pyrolysis biochar could be incorporated as a high-efficiency MEC anode material, and MECs with the inclusion of biochar could provide a feasible way for the treatment of recalcitrant wood vinegar.

近年来,由于水热液化技术可以将高含水率的生物质直接转化为生物原油而极具潜力,引起了人们的广泛关注.该文综述了生物质水热液化研究的最新进展,简述了生物质水热液化的产物分离流程,着重分析了水热液化4种产物(生物原油、水相产物、固体残渣和气体)的产物特性及其利用方式.在4项产物中,生物原油可作为燃料或者从中提炼高附加值产品,水热液化水相可以进行微藻养殖、经厌氧发酵产甲烷或者利用微生物电解池产生氢气等,固体残渣通过进一步处理后可作为生物炭使用,气相产物可作为温室的气体肥料.另外,该文总结了生物质中关键元素在水热液化产物中的分布规律,展望了水热液化技术未来研究方向,以期能为生物质水热液化研究提供参考与借鉴.

The composition of biogas produced by anaerobic digestion (AD) is typically not ideal due to high CO2 content. In the study, cottonwood biochar was used as an enhanced mediator for the continuously stirred tank reactor AD of cornstalk. The effects of substrate loading and biochar dosage on biogas composition, volatile fatty acids (VFAs), NH3-N, and microbial community characteristics were systematically explored. The results showed that the highest volumetric biogas production rate with biochar was 1.40 L/L/d, at the same time, the CO2 content in the biogas decreased by 5.90%, while the CH4 content increased by 7.40%, compared with the values in AD without biochar. Moreover, VFAs were degraded effectively, in particular, the propionic acid concentration decreased by 55.7%. Besides, microbial abundance had positive correlations with environmental parameters. This study could provide valuable information for both the elucidation of strengthening mechanisms of biochar and further large-scale engineering application.

Anaerobic digestion (AD) is commonly used to treat biowastes, however, there are challenges in AD such as low methane yield, intermediate inhibition, and system instability. In this study, the effects of typical biochars on methane yield and microbial variation for AD with straw and cow manure were explored. The results indicated that cumulative methane yield with coconut shell biochar was higher than that without a biochar (319.44 vs. 282.77 mL/g VS). Interestingly, AD with biochars had a secondary methane yield peak, whereas control groups did not show this phenomenon. A suitable dosage (e.g., straw biochar of 2%) improved cumulative methane yield, but excessive addition (4%) could inhibit AD. AD system with biochar was more helpful for the growth of acetoclastic methanogens rather than hydrogenotrophic methanogens. The study demonstrated biochar can indeed enhance AD performance, and microbial community analyses could supply valuable information to elucidate the mechanism of enhancement.

厌氧发酵是中国有机废弃物处理的重要技术途径,但利用厌氧发酵技术在高负荷条件下处理有机废弃物过程中,因有机酸、氨氮等抑制性物质作用,易导致厌氧发酵运行不稳定,处理效率不高等问题.生物炭是生物质材料在无氧或缺氧条件下经高温热解形成的多孔径碳质材料,具有比表面积高,孔隙结构复杂,表面活性基团丰富和导电性强等特性,并被广泛用于厌氧发酵技术研究.近年来国内外研究表明,生物炭能有效强化厌氧发酵,提高厌氧发酵过程中有机废弃物的处理效率.然而,对于生物炭强化厌氧发酵技术途径,目前仍未见系统的梳理和报道.该文对生物炭材料的化学组成、孔隙结构、表面官能团关键因素及生物炭强化厌氧发酵技术的重要途径进行了系统分析和归纳,从生物炭材料的理化性质出发,阐述了生物炭对于厌氧发酵技术的强化效果及强化途径,强化途径主要包括:提升系统缓冲能力、微生物载体作用和强化电子传递等,在此基础上提出了今后生物炭强化有机废弃物厌氧发酵技术的重点研究内容和方向,为开发厌氧发酵强化技术提供指导.