暗河式厌氧反应器处理养猪废水特性及动力学模型研究

发布时间：2018-06-30 20:17

本文选题：暗河厌氧反应器 + 发酵　；参考：《华中科技大学》2016年博士论文

【摘要】：由于养殖废水具有废水量大、有机物质浓度高,及含有丰富的氮磷等营养物质,对水体构成了严重的危害,并制约了养殖业的进一步发展。养殖废水的处理问题成为了目前亟需解决的迫切问题。本文采用暗河式厌氧发酵反应器处理养殖废水,利用废水自身的重力形成一个自上而下的流动体系,解决了原料流态化连续进料出料的关键技术：并利用自身的堆肥系统在堆肥过程中产生的热量为反应器加热保温,保证厌氧反应在中温的温度范围内进行：同时针对厌氧反应的不稳定性,提出了厌氧消化反应过程的监控指标使得能够及时掌握厌氧反应的状态,为大规模处理养殖废水及生产沼气铺平了道路。围绕该工艺的构建,本文展开了以下工作：(1)以春夏秋冬为时间点,分析了堆肥系统对于反应器的保温效果。结果表明,堆肥系统为反应器能够起到很好的保温效果。反应器春夏秋冬四季的平均温度分别可以达到25.2℃,34.6℃,25.6℃和19.3℃。即使在冬天,反应器的最低温度可以达到15.7℃。同时分析了对比了几种不同加热方式的成本,发现堆肥加热方式的成本最低。(2)对暗河式厌氧反应器的最佳运行条件进行了研究,考察了不同的污泥接种率、不同的有机负荷及水力停留时间对厌氧消化产气率、气体成分、有机物去除率的影响,并分析了厌氧消化过程中间产物挥发性脂肪酸、氢气及硫化氢的变化,以及氢气和硫化氢对于厌氧消化过程的影响。实验结果表明,随着接种比和负荷的提升,厌氧反应过程出现了抑制作用,从而导致了产气量和有机物去除率的下降。最佳的污泥接量为35%,最佳的负荷为5.3 gCOD/L,水力停留时间为25天。此时,日平均产气量为26.7 L,最大产气速率为4.96 L/L.d,有机物去除率达到79.10%。(3)以ADM1模型为基础,加入氢气、硫化氢及pH值三种抑制因子,建立了底物降解模型、中间产物生成模型及产气量模型,同时分析了COD、乙酸、丙酸和丁酸对于各个动力学参数的敏感度以及氢气、硫化氢及pH值对于厌氧消化过程的影响。最后比较了氢气、硫化氢及pH值三种因子对于厌氧消化过程的影响大小。结果表明,该模型能够很好的预测厌氧消化过程底物的降解及沼气产气量,同时发现随着负荷的提高,厌氧消化出现了抑制因素,具体体现在氢气和硫化氢浓度的提高。通过k值发现,在最佳的负荷条件下,其有机物的降解速率(km_COD)最大。随着负荷的升高,氢气和硫化氢浓度也随着升高,从而影响了微生物的活性,降低了底物降解速度。从ka、kb和kp的变化可以看出乙酸、丙酸和丁酸转化成甲烷的顺序是丙酸丁酸乙酸。不同负荷条件下的fa值为7.5 (4.2 g/L),6.4 (5.3 g/L),2.0 (7.0 g/L) 4.5 (9.0 g/L);fb值为1.3 (4.2 g/L),1.9 (5.3 g/L),1.2 (7.0 g/L) 1.0 (9.0 g/L);fp值为1.0 (4.2 g/L),2.1 (5.3 g/L),3.3 (7.0 g/L) 2.3 (9.0 g/L);而从fa、fb、fp、的变化,可以看出长链的脂肪酸首先被转化成乙酸,其次是丁酸,最后是丙酸。通过敏感度分析发现,初始的有机物浓度即有机负荷的变化是最影响上述几个变量的因子,这与实验结果一致。(4)针对厌氧消化过程的不稳定性,以葡萄糖、蛋白质、脂类物质及实际的废水模拟负荷扰动实验,分析了厌氧消化系统负荷受到冲击时,产气量、气体成分、pH、总挥发性脂肪酸、单个的挥发性脂肪酸、氢气及硫化氢的变化,以反应速度、监测手段及敏感程度作为选择监控指标的标准。结果表明,反应器在稳态运行的条件下,沼气产量为26.7±3.5 L/d,甲烷含量为62.1%±3.5%,氢气和硫化氢的浓度分别为5±1.5ppm和1000±50 ppm,乙酸、丙酸和丁酸的浓度为5.1±1.5 mg/L、6.5±1.2 mg/L和9.5±1.3 mg/L,总的挥发性脂肪酸的浓度为4.8±1.5mg/L, pH值在6.8-7.05之间。当系统受到负荷冲击时,氢气、硫化氢、产气量、丁酸、总的挥发性脂肪酸对负荷冲击表现出积极的反应,而气体成分、pH、乙酸和丙酸的变化则不明显。几种物质对负荷冲击的响应顺序为：氢气硫化氢丁酸TVFA产气量。但由于丁酸及TVFA监测手段的复杂性及产气量的响应滞后性,最终选择氢气和硫化氢作为厌氧消化过程的监控指标。(5)最后分析了系统的环境效益、能量平衡及经济效益。结果表明,暗河式沼气反应器由于利用自身堆肥产生的热量为反应器保温,与其他的加热方式相比,可以至少节约5倍的能源。此外,由堆肥产生的额外经济效益也十分明显。
[Abstract]:Because of the large amount of waste water, high concentration of organic matter and rich nitrogen and phosphorus, aquaculture wastewater constitutes a serious harm to the water body and restricts the further development of the aquaculture industry. The treatment of aquaculture wastewater has become an urgent problem to be solved at present. This paper uses a dark river anaerobic fermentation reactor to treat culture. Wastewater, using the gravity of the wastewater to form a top-down flow system, solves the key technology for the continuous feeding of raw materials in the flow state of the raw material: the heat produced by its own composting system during the composting process is heated for the reactor to ensure that the anaerobic reaction is carried out in the temperature range of the medium temperature and at the same time against the anaerobic reaction. In response to the instability, the monitoring index of anaerobic digestion process has been put forward to enable the state of anaerobic reaction to be mastered in time, which paved the way for large-scale treatment of aquaculture wastewater and biogas production. Following the construction of this process, the following work has been carried out in this paper: (1) to analyze the composting system for the reactor in spring, summer and winter. The results show that the composting system can have good thermal insulation effect for the reactor. The average temperature of the reactor in spring summer, autumn and winter can reach 25.2, 34.6, 25.6 and 19.3. Even in winter, the minimum temperature of the reactor can reach 15.7. At the same time, the cost of several different heating modes is analyzed and compared. The cost of the current compost heating method is the lowest. (2) the optimum operating conditions of the dark river anaerobic reactor are studied. The different sludge inoculation rate, the different organic load and the hydraulic retention time on the anaerobic digestion and gas production rate, the gas composition and the organic matter removal rate are investigated, and the volatility of the intermediate product in the anaerobic digestion process is analyzed. The changes in fatty acids, hydrogen and hydrogen sulfide, and the effect of hydrogen and hydrogen sulfide on the anaerobic digestion process. Experimental results show that the anaerobic reaction process has a inhibition effect with the inoculation ratio and the increase of load, which leads to the decrease of gas production and organic matter removal rate. The optimum sludge connection is 35% and the optimum load is 5.3 gCOD/. L, the hydraulic retention time is 25 days. At this time, the daily average gas production rate is 26.7 L, the maximum gas production rate is 4.96 L/L.d, the organic matter removal rate is 79.10%. (3) based on ADM1 model, adding hydrogen, hydrogen sulfide and pH value three inhibitory factors, the substrate degradation model, the intermediate product generation model and the gas production model, and the analysis of COD, acetic acid, are established. The sensitivity of propionic acid and butyric acid to various kinetic parameters and the effect of hydrogen, hydrogen sulfide and pH on the anaerobic digestion process. Finally, the effects of three factors such as hydrogen, hydrogen sulfide and pH value on the anaerobic digestion process are compared. The results show that the model can pretest the degradation of substrate and biogas production in the anaerobic digestion process. At the same time, it was found that the anaerobic digestion was inhibited with the increase of the load, which was embodied in the increase of hydrogen and hydrogen sulfide concentration. The K value was found that the degradation rate of organic compounds (km_COD) was the largest under the optimal load condition. As the load increased, the hydrogen and hydrogen sulfide concentration also increased, thus affecting the microorganism. Activity, reducing the rate of substrate degradation. From the changes of Ka, KB and KP, it can be seen that the order of acetic acid, propionic acid and butyric acid into methane is butyric acid propionate acetic acid. The FA value of different load conditions is 7.5 (4.2 g/L), 6.4 (5.3 g/L), 2 (7 g/L) 4.5 (9 g/L), FB value 1.3 (4.2 g/L), 1.9 (5.3 g/L), 1.2 (7 g/L)); 1.2 (7 g/L); For 1 (4.2 g/L), 2.1 (5.3 g/L), 3.3 (7 g/L) 2.3 (9 g/L), and from the changes of FA, FB, FP, it can be seen that the long chain fatty acids are first converted into acetic acid, followed by butyric acid, and finally propionic acid. By sensitivity analysis, the initial organic concentration, that is, the change of organic load is the most influential factor of the above variables, which is the experiment with the experiment. 4. (4) according to the instability of anaerobic digestion process, with glucose, protein, lipid materials and actual wastewater simulated load disturbance experiments, the changes of gas production, gas composition, pH, total volatile fatty acids, single volatile fatty acids, hydrogen and hydrogen sulfide were analyzed when the load of anaerobic digestion system was impacted. Degree, monitoring means and sensitivity are the criteria for selecting monitoring indexes. The results show that the biogas production of the reactor is 26.7 + 3.5 L/d, methane content is 62.1% + 3.5%, hydrogen and hydrogen sulfide are 5 + 1.5ppm and 1000 + 50 ppm respectively, and the concentration of acetic acid, propionic acid and butyric acid is 5.1 + 1.5 mg/L, 6.5 + 1.2 mg/L and 9.5. 1.3 mg/L, the total concentration of volatile fatty acids is 4.8 + 1.5mg/L, and the pH value is between 6.8-7.05. When the system is subjected to load shock, hydrogen, hydrogen sulfide, gas production, butyric acid, and total volatile fatty acids have a positive reaction to the load impact, while the changes of gas components, pH, acetic acid and propionic acid are not obvious. The response sequence is: hydrogen sulfide butyric acid TVFA gas production. But due to the complexity of butyric acid and TVFA monitoring means and the response lag of gas production, the final selection of hydrogen and hydrogen sulfide as the monitoring index of the anaerobic digestion process. (5) finally, the environmental benefits, energy balance and economic benefits of the system were analyzed. The results showed that the dark river type biogas was reversed. The heater can save at least 5 times as much energy as other heating methods because of the heat generated by its own compost. In addition, the additional economic benefits from the composting are also obvious.
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：X713

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