基于pH值调控的厌氧酸化产物分布及微生物群落特征研究

摘要

Two-phase anaerobic digestion (AD) process has been adopted by many researchers as a potential alternative to the traditional single-phase AD process,to alleviate the acid accumulation problem,particularly when easily biodegradable organic solid wastes such as the fruit and vegetable waste and food waste were used as the feedstock.In order to further improve the efficiency and stability of the two-phase AD process,the distribution of anaerobic acidification products was studied under different pH value (4.0,5.0,and 6.0) conditions.Moreover,at the end of the experiment,the microbial communities in the reactors were analyzed and compared.The results showed that pH control could significantly improve the acidification rates of the reactors.At pH values of 5.0 and 6.0,the acidification rates were higher than 70％.The acidification products under the pH value of 5.0 mainly consisted of ethanol,lactic acid and acetic acid.A lot of propionic acid (about 50％ of the total acid production) was observed under the pH value of 6.0.Therefore,the pH value controlled at 5.0 can be expected as the preferred condition for the acidification phase of organic solid wastes.Lactobacillus (8.9％),Prevotella (32.0％),Bifudobacterium (22.4％),Clostridium (22.3％) and Sporolactobacillus (11.4％) were found to be the dominant microorganisms at pH value of 5.0,whose metabolic pathways were well consistent with the mentioned distribution of acidification products.%针对果蔬和餐厨垃圾等易降解有机固体废弃物厌氧消化过程的酸化问题,国内外学者通常采用两相厌氧工艺替代传统的单相厌氧工艺.为进一步提高两相厌氧工艺的高效性和稳定性,文章考察了不同pH值(4.0,5.0和6.0)条件下有机物厌氧酸化产物分布情况和调控效应;并对稳定形成的产酸微生物群落结构进行了分析.结果表明,pH值控制能明显提高反应器酸化率;pH值为5.0和6.0时反应器酸化率较高,其最高值均超过70％,前者酸化产物以乙醇、乳酸和乙酸为主,后者则出现有大量丙酸(约占总产酸量50％),因此,pH值控制为5.0有望作为有机物产酸相的优选条件.pH值为5.0时形成的优势水解酸化菌属主要有Lactobacillus(8.9％),Prevotella(32.0％),Bifidobacterium (22.4％),Clostridium(22.3％)和Sporolactobacillus(11.4％),且优势菌属的典型代谢途径与实验过程中产物分布特征具有很好的一致性.