机械搅拌切割预处理强化污泥发酵产酸性能研究

Improving volatile fatty acids production in sludgefermentation by mechanical cutting pretreatment

针对传统污泥发酵产酸工艺污泥停留时间长、效率低的问题,本文提出一种基于机械搅拌切割作用的污泥预处理技术,研究机械预处理对剩余污泥发酵产酸效果的影响.研究结果表明,机械预处理可实现絮体破碎与细菌破壁溶胞作用,搅拌切割强度为21000 r/min(预处理1)和35000 r/min(预处理2)时,污泥平均粒径由66.7μm降低至21.9μm和16.4μm,污泥破碎程度分别达到10.9%和16.9%.机械预处理可显著提高污泥发酵产酸效果,且随着机械破碎强度的增加,溶解性有机物(SCOD)和挥发性脂肪酸(VFAs)的产量显著提高.发酵第6 d时,SCOD和VFAs产量达到最大,预处理2组SCOD与VFAs最大浓度为5102 mg/L和3469 mg/L,与对照组相比分别提高96.2%和93%.高通量测序结果表明,机械预处理会影响发酵系统微生物种群结构,Firmicutes是发酵系统中的优势种群,在预处理1与预处理2组中的相对丰度分别为88.33%和96.54%,明显高于对照组(84.38%),从而有提高了系统SCOD与VFAs的产量.

In order to solve the problems of long sludge retention time and low efficiency in traditional sludge fermentation process,a new sludge pretreatment technology based on the mechanical stirring was proposed in this study.The effect of mechanical pretreatment on excess sludge fermentation was investigated.The results showed that mechanical pretreatment promoted the sludge flocs disintegration and cell lysis.When the mechanical stirring intensity was 21000 r/min(pretreatment-1)and 35000 r/min(pretreatment-2),the sludge particle size decreased from 66.7μm to 21.9μm and 16.4μm,and sludge disintegration degree was 10.9%and 16.9%,respectively.The sludge fermentation was improved by mechanical pretreatment,the yield of soluble chemical oxygen demand(SCOD)and volatile fatty acids(VFAs)was significantly increased with the increasing of mechanical stirring intensity.The yield of SCOD and VFAs reached the maximum,when sludge retention time was 6 d.The maximum concentration of SCOD and VFAs were 5102 and 3469 mg/L in pretreatment-2 group,which were 96.2%and 93%higher than those of the control group.The high-throughput sequencing analysis showed that microbial community composition was influenced by mechanical pretreatment.Firmicutes is the dominant bacteria in the fermentation system.The relative abundance of Firmicutes in the pretreatment-1 and pretreatment-2 was 88.33%and 96.54%,respectively,which was significantly higher than that of the control group(84.38%),thus increased the yield of SCOD and VFAs.