Study on the Efficiency of the Synchronous Alkali-ultrasonic Pretreatment of the Low Organic Matter Sludge and its Influence on the Microbial Population in the Anaerobic Digestion System

To solve the problem of the low anaerobic digestion efficiency of the minimal organic matter sludge, the study proposes the synchronous alkali-ultrasonic pretreatment technology of the low organic sludge. The research results show that the collaboration between alkali and ultrasonic has significant effects on pretreatment efficiency. The pretreatment efficiency of the sorts is as follows: synchronous alkaliultrasonic treatment > alkali-ultrasonic stepwise treatment > ultrasonic-alkali stepwise treatment > ultrasonic treatment > alkali treatment. The synchronous alkali-ultrasonic treatment system has strong processing effectiveness. Compared with the control group (the raw sludge), the concentrations of the supernatant SCOD and VFAs of the low organic matter sludge after the pretreatment increases by 15.4 times and 59.64 times respectively, and the supernatant that is easily biodegradable organic matter increases by 19.1%. The gas production after alkali-ultrasonic synchronous pretreatment of the anaerobic digestion system of the sludge increases 58% higher than the control group (without pretreatment ). The results of the high-throughput sequencing of 16S rRNA in the anaerobic digestion system of the sludge, at the genus level, show that the dominant functional bacteria in the system mainly includes vadinHA17, Peptoclostridium, Peptostreptococcaceae, Tissierella, Syntrophomonas, Synergistaceae and Aminobacterium. The dominant functional bacteria genera in the systematic archaea group mainly include Methanosaeta (70.33%), Unclassified (2.74%), Methanosarcina (15.49%), Methanobacterium (5.31%), Methanospirillum (2.18%), ARC26 (1.04%), Methanobrevibacter (1.62%). The abundance of functional bacteria at the genus level was higher than that in the control group.