微曝气条件下S-TE剩余污泥溶解性研究

Study on Eexcess Sludge Solubilization in S-TE Process Under Microaeration

研究了微曝气、不同温度条件下S-TE预处理对剩余污泥溶解和各种化学组分变化的影响.结果表明,S-TE污泥溶解存在2种反应(酶催化反应和热解反应)和2个过程:嗜热菌胞外酶(主要为蛋白酶和淀粉酶)首先解聚污泥胶团,进而溶解细菌的细胞壁,水解胞内有机物质.接种嗜热菌Bacillus stearothermophilussp.AT06-1比不接种促进了污泥悬浮固体的溶解,接种条件下最适宜的溶解温度为65℃,此温度下,污泥VSS和TSS溶解率相对于不接种试验提高程度最大,2 d时VSS、TSS溶解率分别达到34.09%和24.16%,比不接种试验同期分别提高了7.57%和6.87%;微曝气条件下SCOD和VFA得到累积,最大累积量达到4 531 mg/L和2 319 mg/L,有利于厌氧消化;此时蛋白酶活性提高也最大.污泥溶解产生的蛋白质被蛋白酶水解,蛋白质浓度先升高后降低.

The effect of S-TE （solubilization by thermophilic enzyme） pretreatment on excess sludge solubilization and changes of chemical components under microaeration and different temperatures was investigated. The results showed that, two reaction mechanisms of enzyme- catalyzed reaction and thermal-hydrolyzed reaction were involved in the S-TE process, which began with depolymerization of sludge floes by exoenzymes including proteases and amylases, followed by cell-walls and organic matters disintegration and hydrolyzation. The solubiozation process with thermophilic bacteria Bacillus stearothermophilus sp. AT06-1 addition was enhanced compared with the control （ the process without the bacteria）. Under the optimum temperature （65 ℃ ）, the solubilization rate of total suspended solid （TSS） and volatile suspended solid （VSS） reached 34.09 % and 24.16 % within 2 days respectively, 7.57 % and 6.87 % higher than the control. The results also revealed that under microaeration operation, the maximal soluble chemical oxygen demand （SCOD） of 4 531 mg/L and volatile fatty acid （VFA） of 2 319 mg/L were obtained, which would be beneficial to the followed anaerobic digestion process. At the same time the activity of protease was dramatically promoted. The protein released from the sludge was hydrolyzed, resulting in an increase of protein concentration at the early stage of the experiment and then a decrease at the later period.