二价铁离子对厌氧发酵及好氧生物脱氮过程的影响

发布时间：2018-07-21 14:44

【摘要】：厌氧生物发酵和好氧生物脱氮均为废水生物处理技术中重要的部分,目前各大污废水处理厂处理原水时大多离不开这两种工艺。随着科技的进步,这两种工艺日趋成熟,但在处理效率上还是需要提高。铁作为活性污泥中微量元素的一种,在微生物细胞内起不可替代的作用。铁元素是微生物细胞内酶的活性中心,是维持细胞稳态的重要元素,促进微生物进行新陈代谢。因此研究铁在废水生物处理中的作用有重要的现实意义。本研究分别采用厌氧发酵反应器和好氧生物反应器进行外加铁源的对照实验。反应器进水均由实验室人工配制,对反应器的运行进行合理调控。厌氧发酵生物处理实验在进水中持续外加二价铁盐,以不同的二价铁离子浓度和蔗糖浓度调整反应器的运行条件,对反应器在各个状态下的理化指标的变化进行检测和分析,并结合荧光光谱图与指标的变化趋势加以验证,探究铁对厌氧发酵过程的影响。好氧生物脱氮实验进行两个阶段,以有、无碳源为区分条件。反应器均接种驯化成熟的好氧污泥,通过改变二价铁浓度,研究铁对硝化反硝化作用的影响,通过测定有关氮元素的指标对脱氮效果进行研究分析,另外通过对污泥粒径的检测考察好氧污泥颗粒化的进程。本研究得到的结论如下:(1)在厌氧发酵的条件下,实验组的出水COD由加入前的438.15 mg·L~(-1)降为332.79 mg·L~(-1),COD去除率由原来的86.3%上升到89.6%,出水糖浓度从15mg·L~(-1)降为2.5 mg·L~(-1)左右。随着进水蔗糖浓度的升高以及Fe~(2+)浓度的降低,出水COD有一定程度上的升高。(2)Fe~(2+)的加入使得反应器的出水p H升高,加铁后的反应器发生厌氧发酵崩溃的时间比未加铁的推迟了11 d。实验进行80 d和124 d(停止外加铁源)的污泥测定的铁含量,分别为24772.6 mg·kg~(-1)和16096.9 mg·kg~(-1),说明持续外加铁源使得铁元素在活性污泥中大量积累;而反应器出水的铁含量始终不超过1 mg·L~(-1)。(3)Fe~(2+)的加入对降解脂肪酸有一定的影响,抑制了生成乙酸的渠道,而丙酸开始大量积累。Fe~(2+)具有一定的絮凝性,可降低水体中SS的浓度。光学显微镜下的厌氧污泥颗粒,加铁生长的颗粒比未加铁的颗粒大,说明二价铁促进厌氧污泥的颗粒化。(4)通过三维荧光的方法,解析出投加铁源的出水含有四种荧光物质:色氨酸、酪氨酸、辅酶F_(420)、类富里酸。各荧光基团的变化情况与理化指标能够一一对应。综合以上结论可知,Fe~(2+)的加入对UASB降解底物蔗糖有促进作用。(5)SBR反应器添加有机碳源乙酸钠进行好氧生物脱氮,Fe~(2+)的加入使得降解氨氮的效率有所提高,硝酸盐氮的生成量也有所增加,但是铁离子的促进作用并不明显。SBR反应器的COD降解效率较高,达到80%以上,且实验组的去除率比对照组的高。说明Fe~(2+)促进有机物的去除。光学显微镜观察发现,实验组的污泥形态比对照组的污泥形态大,说明二价铁促进好氧污泥的颗粒化。(6)无有机碳源的条件下,当进水Fe~(2+)浓度为0.002 mg·L~(-1)、0.5 mg·L~(-1)、1mg·L~(-1)时,氨氮转化率分别为98.4%、99%、99.2%,反应器的总氮去除率分别为37.5%、37.3%、37.6%,Fe~(2+)对总氮的影响不大。亚硝酸盐氮和硝酸盐氮在生成量上也有少许增加,但从总体来看,Fe~(2+)的影响不甚明显。外加Fe~(2+)后,出水的Zeta电位比进水的电位低,且进出水的电位差变大。Zeta电位越低,说明活性污泥的絮凝效果好,该结论在污泥粒径的测定中得到了证实。随着Fe~(2+)浓度的增大,相应条件下的颗粒污泥D50也逐步增加。
[Abstract]:Anaerobic biological fermentation and aerobic biological denitrification are both important parts of the biological treatment technology of wastewater. At present, most of the wastewater treatment plants are mostly inseparable from these two processes. With the progress of science and technology, these two processes are becoming more mature, but the efficiency of treatment still needs to be improved. Iron is a kind of trace element in activated sludge. It plays an irreplaceable role in microbial cells. Iron is the active center of the enzyme in the microorganism cell, is an important element to maintain the homeostasis of the cell, and promotes the metabolism of the microorganism. Therefore, it is of great practical significance to study the role of iron in the biological treatment of wastewater. A controlled experiment on the iron source was carried out in the reactor. The influent of the reactor was artificially prepared by the laboratory, and the operation of the reactor was reasonably regulated. The anaerobic fermentation biological treatment experiment continued to add two valent iron salt to the influent, and adjusted the operating conditions of the counter with different concentration of two valence iron ions and the concentration of sucrose, and the reactor was in various states. The changes of physical and chemical indexes were detected and analyzed, and the influence of iron on the anaerobic fermentation process was examined in combination with the change trend of fluorescence spectra and indexes. The aerobic biological denitrification experiment was carried out in two stages, with the presence of carbon free source as the distinguishing condition. The reactor was inoculated and domesticated aerobic sludge, and the concentration of two iron was changed by changing the concentration of iron. The effect of iron on nitrification and denitrification was studied and the effect of nitrogen removal was studied and analyzed. In addition, the process of aerobic sludge granulation was examined by the detection of the particle size of the sludge. The results of this study were as follows: (1) under the anaerobic fermentation conditions, the effluent COD of the experimental group was 438.15 mg. L~ before joining. 1) reduced to 332.79 mg. L~ (-1), the removal rate of COD increased from 86.3% to 89.6%, and the effluent sugar concentration was reduced from 15mg to L~ (-1) to 2.5 mg. L~ (-1). With the increase of sucrose concentration and the decrease of Fe~ (2+) concentration, the effluent had a certain degree of increase. (2) the addition of the effluent to the reactor increased the effluent and the reaction after iron added. The time of anaerobic fermentation to collapse was delayed by 11 D. experiments to carry out the iron content of 80 D and 124 D (stop the iron source). The iron content was 24772.6 mg. Kg~ (-1) and 16096.9 mg. Kg~ (-1), indicating that the iron content was accumulated in the activated sludge, and the iron content of the reactor effluent was always not. The addition of 1 mg. L~ (-1). (3) the addition of Fe~ (2+) has a certain effect on the degradation of fatty acids, which inhibits the channel of producing acetic acid, and propionic acid begins to accumulate a large amount of.Fe~ (2+) with a certain flocculation, which can reduce the concentration of SS in the water body. The anaerobic sludge grains under the optical microscope are larger than those without iron, indicating two valence iron. Promote the granulation of anaerobic sludge. (4) through the three-dimensional fluorescence method, it is found that the effluent of the iron source contains four kinds of fluorescent substances: tryptophan, tyrosine, coenzyme F_ (420), and fulvic acid. The changes of the fluorescent groups and the physical and chemical indexes can correspond to one by one. The conclusion is that the addition of Fe~ (2+) to the UASB degradation substrate sucrose (5) SBR reactor added organic carbon source of sodium acetate for aerobic biological denitrification. The addition of Fe~ (2+) increased the efficiency of ammonia nitrogen degradation and increased the production of nitrate nitrogen, but the promoting effect of iron ions was not obvious in the COD reduction efficiency of the.SBR reactor, reaching more than 80%, and the ratio of removal rate of the experimental group was more than that of the experimental group. The height of the control group showed that Fe~ (2+) promoted the removal of organic matter. The optical microscope observed that the sludge form of the experimental group was larger than that of the control group, indicating that the two valence iron promoted the granulation of aerobic sludge. (6) when the concentration of the influent Fe~ (2+) was 0.002 mg. L~ (-1), 0.5 mg. L~ (-1), 1mg L~, the transformation of ammonia nitrogen The total nitrogen removal rates were 98.4%, 99% and 99.2% respectively. The total nitrogen removal rates of the reactor were 37.5%, 37.3%, 37.6%, and Fe~ (2+) had little effect on the total nitrogen. The nitrite nitrogen and nitrate nitrogen had a little increase in the amount of production, but in general, the effect of Fe~ (2+) was not obvious. After adding Fe~ (2+), the Zeta potential of the effluent was lower than that of the water, and in and out of water. The lower the potential difference, the lower the.Zeta potential, which indicates that the flocculation effect of activated sludge is good. This conclusion has been proved in the determination of the size of the sludge. With the increase of the concentration of Fe~ (2+), the granular sludge D50 under the corresponding conditions is also gradually increased.
【学位授予单位】：安徽建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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