| Nowadays, the disposal and comprehensive utilization of waste activated sludge(WAS)has become a global focus, due to industrial and municipal wastewatertreatment plants produce large amounts of WAS. Based on the lysis of microbial cell is akey step in the process of sludge digest, sludge lysis method provides a new direction ofresource utilization of sludge.In this article, the feasibility of thermophilic micro-aerobicconditions to improve the performance of waste activated sludge lysis was explored.The study was carried out from the following aspects: the conditions of pretreatmentand analysis of microbial community. The degradation of microbial cell protein wascombined with analysis of microbial community to study the lysis efficiency andmechanism of thermophilic micro-aerobic pretreatment to sludge.At first, the aeration rate and temperature parameters of affecting sludge lysis wererespectively optimized. The experiment group reactor was aerated gradiently, and theoptimized aeration pattern was obtained. The reaction temperature was furtheroptimized, and the Escherichia coli were selected as a type strain to simulate thepretreatment experiment. The SDS-polyacrylamide gel electrophoresis (SDS-PAGE)was applied to observe protein degradation of Escherichia coli before and afterpretreatment. According to the optimized patterns condition, the activated sludge andEscherichia coli were respectively scanned by scanning electron microscopic (SEM) toobserve the effect of thermophilic micro-aerobic pretreatment conditions to structureand morphology of microbes.The result of study shows that the pretreatment effect of experiment group wasobvious when the aeration rate was0.07vvm at70℃for24h. The sludge lysis of thehigh concentration of organic matters such as protein and total sugar was shown. Thiswas benefit to the lysis of waste sludge, and the biodegradability of waste activatedsludge was obviously enhanced. Protein was detected in supernatant after theEscherichia coli were pretreated in thermophilic micro-aerobic conditions. And the cellwalls of Escherichia coli were cracked, and it further proveds that thermophilicmicro-aerobic pretreatment for lysis of waste sludge was favorable. This could promotemacromolecule organic matters through cell walls, and they were used as nutrients byacid-producing micro-organism. Based on the results of scanning by SEM, the effect ofwaste sludge pretreated in thermophilic micro-aerobic conditions on the lysis andhydrolysis of microbial cell&zoogloea was obvious. The concentrations of organicmatters such as protein and carbohydrate were significantly increased.Anaerobic fermentation for WAS that was pre-treatmented with thermophilicmicro-aeration method was studied, and using denaturing gradient gel electrophoresis(DGGE) technique to analysis of microbial community characteristics. The result showed that acid-producing ability was exhibited by the WAS disposed of thermophilicmicro-aeration，acid production reached3149mg COD/L when the WAS was processedby thermophilic micro-aeration for96h, especially acetic acid increased by50%of totalproduction, it can be used as the substrate for further using. PCR-DGGE analysisshowed that Microbial diversity within the system was influenced by differentpretreatment conditions. Microbial community in the pretreated WAS quickly adjustedto adapt to environmental changes during anaerobic acidogenic fermentation. Microbialspecies such as rhodocyclus、β-proteobacteria bloomed, which played a major role inthe Anaerobic reactor. This is important for the explanation for the efficient acidproduction during the anaerobic fermentation of WASIn conclusion， through the analysis of WAS pre-treatment in thermophilicmicro-aerobic method and the improvement of sludge digestion,it provides a new ideafor applying and sludge resource recovery. |
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