【作者】 赵维纳；

【导师】 李小明；

【作者基本信息】 湖南大学 ， 环境工程， 2008， 硕士

【摘要】 随着城市废水处理量的增加,下水道接管率的提高和活性污泥(AS)系统的扩建,产生大量无法避免的污泥,新生剩余污泥的减量化及资源化的研究成为国际新趋势。根据生物处理工艺中影响剩余污泥产生的可能途径,将污泥减量技术分为降低细菌合成量的解偶联技术、增强微生物利用二次基质进行隐性生长的各种溶胞技术,介绍了各种技术的研究现状,并比较了减量效果和优缺点。基于微生物隐性生长的生物嗜热酶溶解(S-TE)技术,该技术经济高效、安全,而且能耗低、易于运行控制,结合后续工艺不仅可以实现污泥的“零排放”,还可同时实现废水的高效生物降解或沼气产能的增加,应用前景良好。研究了S-TE预处理对剩余污泥溶解和各化学组分变化的影响。在剩余污泥中接种含混合嗜热菌的驯化种泥,通过实验运行,考察了不同温度下污泥固体有机物的溶解变化情况。结果表明,接种嗜热菌相对于不接种试验更促进了污泥悬浮固体的溶解。接种最适宜的温度为65℃,该温度下,56h内TSS和VSS溶解率最大可达31.94%和48.04%,而不接种条件下最大溶解率仅为19.69%和28.82%。微曝气条件下接种后的SCOD得到累积,65℃、72h时出现SCOD最大值4699mg/L,有利于厌氧消化。由于接种混合嗜热菌促进了蛋白质的溶解,蛋白质和氨氮含量先升后缓慢降低,说明S-TE过程中蛋白质的溶解和氨氮浓度的变化均为动态平衡的结果。本论文研究了含混合嗜热菌的不同种泥/处理污泥比例下的污泥中固体有机物溶解效率的变化,同时监测了在此条件下各个反应器中的酶活性的变化曲线,最后,为了更好的反映在污泥系统中固体有机物受到嗜热菌种泥影响的程度并对污泥固体有机物溶解的动力学进行了初步的探讨。实验结果表明,不同种泥/处理污泥比例下,对污泥中固体有机物溶解的促进程度有所不同,且污泥溶解速率也有所不同。当种泥/处理污泥比例为3时,VSS溶解率达到最大值60.5%。此外,不同种泥/处理污泥比例条件下VSS和TSS溶解过程在初始阶段(t=12h)都符合一级反应动力学模型。本文对S-TE污泥溶解受到溶解氧因素的影响也进行了探讨,DO=1mg/L为实验条件下最佳溶解氧浓度,而当DO浓度增大,VSS去除率反而降低。分析其可能的原因,也许是因为单纯的加大曝气量,不仅不能使氧转移效率提高,反而会起到散热的作用,使得系统温度降低,达不到嗜热菌对温度的要求,从而对VSS的去除不利。更多还原

【Abstract】 With the increase of amount of municipal wastewater and sewer-laid rates and expansion of active sludge (AS) system, it brings about large amount of sludge and generates a new international tendency of sludge minimization and resource utilization. According to production principle of excess activated sludge in biological treatment process, the possible approaches for sludge reduction may be based on there aspects: uncoupling metabolism, cryptic growth enhanced through cell lysis. Relevant research works were reviewed, and characteristics of each technology were compared. Compared with other sludge solubilization technology such as ozone oxidation, chlorine oxidation, thermal hydrolysis, acid, alkali, mechanical, ultrasonic and enzymatic directly pretreatment, solubilization by thermophilic enzyme(S-TE) based on microbial cryptic growth is more cost-effective and safer as well as lower energy cost and easier operation. Combined with the following process, S-TE not only can realize sludge "zero discharge", but simultaneously realize high effective wastewater biodegradation or enhancement of biogas production.The influence of S-TE (Solubilization by Thermophilic Enzyme) pretreatment on excess sludge characteristics and changes of chemical components was investigated. The domesticated seed sludge containing mixed thermophilic bacterium was inoculated in excess sludge, and the solubilization of solid organic substance under different temperature was examined by way of batch operation. The results show that thermophilic bacterium promoted the dissolution of sludge, and the optimum temperature for thermophilic enzyme solubilization was 65℃, in which the solubilization rate of total suspended solid (TSS) and volatile suspended solid (VSS) reached 31.94% and 48.04% within 56h, which were improved by 7.57% and 6.87% than that without inoculation. The maximal soluble chemical oxygen demand (SCOD) can be reached at 4699 mg/L at 65℃, 72h, which would be beneficial to the further anaerobic digestion process. On account of the inoculation of mixed thermophilic accelerating dissolve of protein, the protein and ammonia concentration raise a lot and then fall slowness, which make out that homeostasis of protein dissolving and ammonia concentrations was exists in S-TE process.The influence of different DS/FS(DS:digested sludge; FS:feed sludge) ratio was also investigated in this study.The impact of the ration was evaluated with respect to its capability for removal of the total suspended solids(TSS) and volatile suspended solids(VSS). The DS/FS ratio 3 results in the maximum VSS 60.5%. The increase of the DS/FS ratio associated with increased in VSS and TSS destruction, respectively. The protease activity was caculated to suggest the ability of thermophilic bacteria in the sludge treatment to degradation of organic solids. Assuming pseudo-first-order kinetics, it was shown that while organic solid destruction rate constants (k) are inversely related to DS/FS ratio.The effect of the dissolve of dissolved oxygen (DO) on the excess sludge solubilization by the S-TE technology is studied in this paper. The optimical DO is 1mg/L for the sludge solubilization in the experiment. And the removal rate of the VSS is decrease when the DO increased. The most capable reason for this is, the simply increase of the aeration, not only can not improve the excharge of the dissolved oxygen (DO), but also push the heat into the air. This process leads to a decrease of the temperature. Thus, the temperature can’t meet the need of the thermophilic bacteria and as a result of the solids solution rate decrease.更多还原