蠕虫反应器减量剩余活性污泥系统的CFD模拟、优化设计及经济性评价

发布时间：2018-06-13 10:15

本文选题：数值模拟 + 蠕虫反应器　；参考：《内蒙古工业大学》2017年硕士论文

【摘要】：随着我国人口的增加和经济的发展,剩余污泥的产量逐年增加,污泥处理的费用已经成为污水处理领域的瓶颈,近年来,基于微型动物捕食作用的污泥减量技术从源头上减少污泥产量,具有纯生态、无二次污染等优点,越来越受到重视。但目前蠕虫反应器的稳定性无法保证,而影响蠕虫生长的主要因素是反应器内部流场的变化和溶解氧的分布,因此,本文采用数值模拟与试验验证相结合的方法,研究蠕虫反应器内不同曝气量及蠕虫投放位置对污泥减量效果的影响,并与常规污泥处理处置方法对比,进行经济性分析评价。利用ANSYS FLUENT 16.0提供的欧拉两相流模型和标准k-ε湍流模型,对蠕虫反应器内部速度场、含气率以及湍流强度等分布进行了数值模拟分析,得到了蠕虫在反应器内的最优投放位置且曝气量约为0.2m3/h时,污泥减量效果最好。构建以序批式反应器(SBR)为主体工艺并联合蠕虫减量反应器的生活污水处理系统,对上述模拟结果进行试验验证;试验结果表明,污泥减量率(以质量计)最高时为23%,此时反应器内蠕虫投放在最优位置且曝气量约为0.2m3/h,验证了模拟结果的可靠性;进一步通过响应曲面法(BBD分析法)对蠕虫减量污泥效果的三个影响因素(曝气量、蠕虫投放位置、减量污泥浓度)进行试验分析,结果与理论最优值吻合良好,佐证了数值模拟结果的可靠性。以最优工况(曝气量0.2m3/h、蠕虫最优投放位置P2)运行SBR-蠕虫减量污泥反应器系统,与SBR-常规污泥处理工艺系统进行经济性对比分析。蠕虫摄食污泥释放的氨氮和总磷回流到SBR反应器导致总氮、总磷增加了4%、12%,相应地造成SBR污水处理系统每日处理费用增加约130.076元/m3水;经蠕虫摄食后的剩余污泥脱水性能提高,后续常规污泥处理的消化池、污泥脱水、污泥干化设备费用明显减少。有蠕虫减量的污泥处理较无蠕虫减量的污泥处理总基建费用节省了约19万元/t污泥,每日运行费用节省了4.6元/t污泥;除此之外,每日产生的蠕虫可创造经济价值约为460元/t污泥,这完全可以抵消掉有蠕虫减量时SBR污水处理系统所增加的处理费用。因此,利用蠕虫进行污泥减量从经济上是可行的,更重要的是其可以实现生态循环,具有良好的应用前景。
[Abstract]:With the increase of population and economic development in China, the output of excess sludge is increasing year by year, and the cost of sludge treatment has become the bottleneck in the field of sewage treatment. Sludge reduction technology based on predation of microfauna has been paid more and more attention because of its advantages of reducing sludge production from source, having the advantages of pure ecology and no secondary pollution. However, the stability of helminth reactor cannot be guaranteed at present, and the main factors affecting worm growth are the variation of flow field and the distribution of dissolved oxygen in the reactor. Therefore, the method of numerical simulation and experimental verification is used in this paper. The effect of different aeration amount and worm position on sludge reduction in helminth reactor was studied, and compared with conventional sludge treatment and disposal methods, economic analysis and evaluation were carried out. Using the Euler two-phase flow model and the standard k- 蔚 turbulence model provided by ANSYS fluent 16.0, the velocity field, gas holdup and turbulence intensity in the helminth reactor were numerically simulated and analyzed. The best sludge reduction effect was obtained when the optimal placement of worm in the reactor and the aeration rate was about 0.2m3/h. A domestic wastewater treatment system with sequencing batch reactor (SBR) as the main process and a worm decrement reactor as the main process was constructed, and the above simulation results were tested and verified. The sludge reduction rate is 23 when the sludge reduction rate is the highest, and the worm in the reactor is placed in the optimal position and the aeration rate is about 0.2 m3 / h, which verifies the reliability of the simulation results. Three factors (aeration rate, worm position, sludge concentration) of worm sludge reduction were analyzed by response surface method (BBD analysis). The results are in good agreement with the theoretical optimal value. The reliability of the numerical simulation results is verified. SBR- worm sludge reduction reactor system was operated under the optimal operating conditions (aeration rate 0.2 m3 / h, worm optimal placement position P2), and compared with SBR- conventional sludge treatment process system. The return of ammonia nitrogen and total phosphorus released by worm feed sludge to SBR reactor led to total nitrogen, total phosphorus increased by 4% and 12%, which resulted in the increase of daily treatment cost of SBR sewage treatment system by about 130.076 yuan / m ~ 3 of water, and the dewatering performance of surplus sludge after worm feeding was improved. The cost of sludge dewatering and sludge drying equipment in the digesting tank of conventional sludge treatment was obviously reduced. The total infrastructure cost of treating sludge with worm reduction is about 190000 yuan / t compared with the total infrastructure cost of non-worm reduction sludge treatment, and the daily operating cost is 4.6 yuan / t sludge savings; in addition, The daily production of worms can create an economic value of about 460 yuan / t of sludge, which can completely offset the increased treatment cost of SBR sewage treatment system with worm reduction. Therefore, it is economically feasible to use worm to reduce sludge, and more importantly, it can realize ecological cycle, which has a good application prospect.
【学位授予单位】：内蒙古工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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