餐厨垃圾产氢产丁醇阶梯发酵过程机制解析

The market competitiveness of biohydrogen and biobutanol which played as energy carrier could be improved if food waste and other municipal solid wastes (MSW) be applied as the feedstock. From our previous research, food waste could be decomposed rapidly by the two strains of Bacillus sp. and Yokenella sp. screened from anaerobic activated sludge for hydrogen production. However, nearly half of the organics was left in the acidic wastewater in the form of acetate and butyrate. In this project, the step fermentation of food waste for hydrogen and butanol production was proposed and its mechanism was deeply analyzed. Based on the synergistic effect of the two strains, food waste was rapidly decomposed for hydrogen production. Moreover, the accumulation of acetate and butyrate was strengthened by regulating environmental factors. Thus the response mechanism of hydrogenogen to environmental factors and metabolite was revealed. The higher yield butanol-producing microbe was screened from the nature world, and its genus was identified by morphological observation and 16S rDNA sequencing. The screened butanol-producing bacteria were then utilized for acid wastewater treatment for butanol production. In addition, the variation of metabolite during butanol fermentation process was analyzed by gas chromatography, mass spectrometry and other methods. Based on the numerical analysis, the growth and inhibition models of butanol-producing microbe were established. Finally, the growth regularity of butanol-producing microbe in the acid wastewater and its response mechanism to butanol accumulation were expounded. This project could provide scientific basis for further development of MSW and low cost production of biobutanol.

采用餐厨垃圾等市政固体废弃物为原料能够提高生物氢气和丁醇作为能源载体的市场竞争力。前期从厌氧活性污泥分离出的Bacillus sp.和Yokenella sp.产氢菌能够快速降解餐厨垃圾产氢，但仍有近一半的有机质以乙酸和丁酸的形式残留在废水中。本项目提出构建餐厨垃圾产氢产丁醇阶梯发酵系统并深入解析其发酵机制。基于两株产氢菌的协调作用快速降解餐厨垃圾产氢，通过环境理化因子调控定向强化乙酸和丁酸生成，揭示A、B产氢菌相互协调机制及其对代谢产物累积响应机制。从自然界中筛选高产丁醇功能菌，通过形态学观察和16S rDNA测序等技术鉴定其种属，并将其用于产氢酸性废水丁醇转化。采用色谱、质谱等手段分析丁醇发酵过程代谢产物变化，基于数值分析建立丁醇菌生长与抑制模型，阐明丁醇菌在产氢酸性废水中生长规律及其对丁醇累积响应机制。项目的完成将为市政固体废弃物深入开发和生物丁醇低成本生产提供科学依据。

采用餐厨垃圾为原料生产氢气和丁醇能够降低生物质能源的原料成本，提高能源燃料的经济性能。项目研究了餐厨垃圾预处理、生物产氢和生物丁醇发酵性能。从碱处理后活性污泥分离出的两株产氢菌均为杆状细菌，分别为Enterobacter cancerogeous HG6 2A和Enterobacter homaechei 83。对两株产氢菌的混合发酵性能进行了研究，研究结果表明混合发酵能够明显提高氢气得率，两株产氢菌混合发酵能够克服单菌发酵时的缺陷，两株菌的协同作用是混菌发酵性能提高的原因。从自然界筛选到的NG1311、NG132和CC三种产丁醇菌株发酵7%玉米醪结果表明，NG1311丁醇产量最高，丙酮和丁醇产量分别为0.6和0.8 g/L。研究了不同的餐厨垃圾预处理方法，超声-热处理法是餐厨垃圾预处理最佳方法。通过C. acetobutylicum CICC8009和C. acetobutylicum CICC8012混合发酵可预处理后的餐厨垃圾丁醇产量，混合发酵的最佳比例为7:3，对应的丁醇产量为3.1 g/L；油醇萃取条件下，丁醇产量可提高至23.3 g/L，提高了665%，油醇将水相中的丁酸和丁醇及时萃取，减轻了丁酸和丁醇对丁醇菌的抑制作用，是丁醇产量提高的主要原因。项目研究为生物氢气和生物丁醇的低成本开发提供了科学依据。