蔬菜类废物两相厌氧消化水解酸化相颗粒降解规律

研究蔬菜类废物两相厌氧消化过程中水解酸化液物化性质随水解时间的变化情况,结合总有机碳(TOC)、溶解性有机碳(DOC)、颗粒粒径和溶解性有机物(DOM)分子量的分析,探讨了蔬菜类废物水解酸化过程中TOC溶出和颗粒降解之间的关系,分析了水解酸化相颗粒物降解规律.实验结果表明,蔬菜类废物水解过程可以分成两个阶段:易水解的颗粒物在前5d迅速水解,TOC浓度迅速升高,在第5d达到最大值4920mg/L,水解产生颗粒态物质的二次平均直径从第1d的58.38μm降至第5d的4.64μm,有机物快速溶出,DOC/TOC比值在第4d达到最大值85%,该水解过程可用Contois模型模拟;第5d后,难水解颗粒物质的缓慢水解起主导作用,颗粒态物质的二次平均直径从4.64μm开始逐渐增大,并稳定在8.97~10.68μm范围内,TOC和DOC溶出率逐渐降低,且DOC溶出率小于TOC溶出率.大分子溶解性有机物的降解也主要集中在水解过程的前5d,水解第1d产生的大分子DOM(1.6×109~1.9×109Da)到第5d已经全部降解成分子量在5×104~4×106Da的DOM;第5d过后,DOM的分子量分布情况并未发生较大变化.表明蔬菜类废物两相厌氧消化工艺过程中水解时间可缩短为5d.

Particle hydrolysis during the two-phase anaerobic digestion of vegetable waste

During the two-phase anaerobic digestion process of vegetable waste, changes of hydrolytic acidification liquid’s physical-chemical properties were investigated. The relationship among dissolution of total organic carbon (TOC), dissolved organic carbon (DOC) and particulate degradation was discussed. The mechanism of particle hydrolysis acidification was assessed by combining the trend of TOC, DOC, particle size distribution and molecular weight evolution. The experiment results showed that, the hydrolysis process of vegetable waste could be divided into two stages. In the first five days, particulates with high degree of hydrolysis began to hydrolyze quickly. The TOC value rose rapidly, reaching the maximum of 4920mg/L in the fifth day. The quadratic mean diameter of particulates generated from hydrolysis dropped from 58.38 μm in the first day to 4.64 μm in the fifth day. Furthermore, organic matter dissolved rapidly, with a maximum of 85% DOC/TOC ratio. This process could be simulated by Contois hydrolysis model. After the fifth day, the slow hydrolysis of difficult recalcitrantly-hydrolyzed particulate played a dominant role. The quadratic mean diameter of particulates began to increase gradually then stabilized in the range of 8.97~10.68 μm. The dissolution rate of TOC and DOC gradually decreased. DOC dissolution rate was less than the TOC dissolution rate. The distribution diagram of dissolved organic matter (DOM) showed that the degradation of macromolecule DOM mainly concentrated in the first 5days. All of the macromolecule DOM with molecular weight between 1.6×109~1.9×109Da degraded to DOM between 5×104~4×106Da. The distribution of DOM changed a little after the 5th day. It was recommended that hydrolysis time could be shortened to 5 days during a two-phase anaerobic digestion of vegetable waste.