碱—热低温预处理改善剩余污泥厌氧消化效能的研究

发布时间：2018-03-21 13:21

  本文选题：剩余污泥　切入点：碱-热低温预处理　出处：《西安理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着我国城镇基础设施的不断完善,城镇污水处理厂污水处理率显著提高,二级生化过程产生的剩余污泥量也大幅增加。对污泥进行厌氧消化处置,将污泥中的有机质转化成能量物质进行再生利用,是未来污水处理厂实现可持续运行的关键。但受剩余污泥胞外结构和细胞的细胞壁难以破壁水解的影响,致使污泥水解发酵过程缓慢,在一定的时间内产气效率低下,有机质最终的利用率低,不仅制约了污泥厌氧消化技术的推广实施,还影响消化后污泥的最终处置。通过污泥预处理技术破坏剩余污泥的胞外结构,加速细胞破壁水解,可有效改善污泥厌氧消化效能。本课题采用碱-热低温热水解预处理技术,以药剂和热能消耗量最小为条件,获得污泥碱-热低温预处理的最优参数,以使在加速细胞破壁水解的同时节约预处理能耗;开展污泥厌氧消化生物化学甲烷势(Biochemical Mathane Potential,BMP)实验,探讨碱-热低温预处理提高污泥厌氧消化产气效率的程度及实践应用的可行性。获得的研究结果如下:1、通过正交实验,确定了碱-热预处理的最佳运行参数。污泥在不同水热温度(70℃、80℃、90℃)、不同水热时间(7h、8h、9h)、不同碱剂量(0.025、0.05、0.075g/gTSNaOH)预处理条件下,进行正交实验,在药剂与热能消耗量最小的条件下,SCOD溶出率、上清液中蛋白质、碳水化合物的浓度达到最大时,获得了碱-热预处理最佳运行条件为水热温度为70℃、NaOH剂量为0.025g/gTS、水热时间为8h;污泥经预处理,VSS/TS平均从57.5%下降到45.9%,VSS去除率约为12%,污泥的沉降性能最好,SV为55.3%。2、水热温度及NaOH剂量对污泥的破解程度影响显著。实验结果表明:随着水热温度的升高(从50℃升高到100℃),污泥絮体和细胞的破碎程度增加显著,SCOD、蛋白质和碳水化合物的溶出和释放量分别增加了 6.5倍、4.5倍和36.9倍,且在70℃左右时,溶出和释放速率显著增加;释放出的物质的分子量随温度升高呈逐步降低趋势,在水热温度为70℃以上时,污泥热解产物中小分子量物质所占比重较大,这有助于后续厌氧消化反应的进行。随着碱剂量的增加,从污泥中溶出的SCOD、蛋白质、碳水化合物和总磷的含量不断增大;当NaOH的剂量大于0.05g/gTS时,蛋白质和总磷的含量急剧增加,说明此时大部分细胞的细胞壁发生了破裂,使大量的细胞物质释放出来,而当NaOH的剂量在0-0.05g/gTS时,仅发生了污泥细胞外部的絮体离散和解体及小部分细胞的破解。3、经碱-热预处理后的污泥及上清液,厌氧消化效能得到较大改善。污泥经碱热预处理和厌氧消化处理(15d)后,污泥混合液和上清液VSS的去除率分别为31%和37%,比原污泥分别高出15%和21%;甲烷产率分别为154.29mLCH4/gVSS和55.14mLCH4/gVSS,比原污泥分别高出6.6倍和1.7倍。
[Abstract]:With the continuous improvement of urban infrastructure in China, the sewage treatment rate of urban sewage treatment plant has been significantly increased, and the excess sludge produced by the secondary biochemical process has also increased significantly. Converting organic matter from sludge into energy material for regeneration is the key to realize sustainable operation of sewage treatment plant in the future. However, it is difficult to hydrolyze the cell wall by the extracellular structure of excess sludge and cell wall. The process of sludge hydrolysis and fermentation is slow, the efficiency of gas production is low and the utilization rate of organic matter is low, which not only restricts the popularization and implementation of sludge anaerobic digestion technology. It also affects the final disposal of sludge after digestion. By using sludge pretreatment technology to destroy the extracellular structure of excess sludge and accelerate cell wall breaking hydrolysis, the anaerobic digestion efficiency of sludge can be effectively improved. The optimum parameters of alkali-thermo-low temperature pretreatment of sludge were obtained under the condition of minimal consumption of medicament and heat energy, in order to accelerate cell wall breaking hydrolysis and save energy consumption of pretreatment, the sludge anaerobic digestion of biochemical methane potential Biochemical Mathane potential (BMP) experiment was carried out. This paper discusses the degree of improving the efficiency of anaerobic digestion of sludge and the feasibility of practical application of alkali-thermo-low temperature pretreatment. The results obtained are as follows: 1, through orthogonal experiment, The optimum operation parameters of alkali-thermal pretreatment were determined. The orthogonal experiments were carried out under the conditions of different hydrothermal temperature 70 鈩，

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