剩余污泥厌氧发酵产物利用与光谱分析

发布时间：2018-08-28 08:53

【摘要】：目前城市污水厂剩余污泥厌氧发酵液资源化利用是环境领域研究的热点问题之一,剩余污泥发酵过程中产生大量的有机物(如蛋白质,糖类,挥发性脂肪酸)以及氨氮和正磷酸盐。发酵液中获得的VFA可作为城市污水厂生物反硝化脱氮的碳源,然而发酵液中含有高浓度的氮磷,若不去除直接投加到污水处理构筑物,会增大污水处理负荷,影响生物脱氮效率。因此本文通过对发酵液中氮磷进行回收以及将VFA作为污水处理反硝化碳源,从而实现发酵液的资源化利用。首先,本实验采用蔗糖模拟废水来研究有机物的厌氧发酵过程,研究有机负荷冲击下对厌氧产甲烷过程VFA积累的影响,并结合平行因子法对厌氧产甲烷发酵液光谱进行解析,确定有机负荷冲击下发酵液中荧光物质的变化以及VFA的积累情况。结果表明:正常运行状态下反应器的荧光物质为蛋白质、辅酶NADH、辅酶F420。当反应器的底物浓度突然增加时,反应器出水的荧光光谱亦发生改变,辅酶F420荧光强度显著降低,反应器出水中的荧光组分以色氨酸、酪氨酸和辅酶NADH为主,表明产甲烷反应受到了抑制。底物浓度增加后,反应器出水的COD和残余底物的蔗糖浓度先显著增加后逐渐减少,VFA浓度先增加后趋于平稳,稳定后反应器的VFA浓度维持在360mg/L左右。原因是反应器受到外界冲击负荷的影响,产甲烷过程受到抑制,无法将COD和VFA降解,待抑制解除后产甲烷能力恢复,COD浓度和糖的浓度减少,VFA浓度趋于平稳。其次,通过比较加碱和未加碱条件,对剩余污泥发酵过程中细胞物质的释放特性进行表征,同时将发酵产物中氮磷以鸟粪石形式进行回收,研究pH、P/N、Mg/P对鸟粪石形成的影响,确定最佳的工艺条件。结果发现:碱性剩余污泥发酵过程中释放的有机物明显高于未加碱条件下的剩余污泥厌氧发酵释放的有机物,且两反应器发酵液的VFA浓度分别在第6d和第7d达到最大值,最大值分别为470mg/L和248mg/L,因此生物反硝化实验可选择第6d发酵液作为生物反硝化脱氮碳源。氮磷回收实验中,当p H=10,P/N=1.1,Mg/P=1.5;此时同时回收氮磷效率相对较高,氮和磷的回收率分别为94.3%和88.1%,88.0%和78.0%,89.9%和78.2%。碱性剩余污泥发酵液氮磷回收后,其发酵液的性质与厌氧产甲烷反应器发酵液性质基本相似,因此以鸟粪石形式回收氮磷后可作为外加碳源投加到氧化沟反应器。最后,通过添加不同种类的碳源(葡萄糖和发酵液)与未加碳源时(空白组)作比较,研究反应器氮和COD的变化来确定选择既经济又有效的外加碳源,并对不同工况下反应器运行状态进行光谱表征。结果表明:添加外加碳源氧化沟工艺脱氮效果比空白对照组脱氮效果明显提高,其中TN去除率平均为85.0%,较空白组提高27.1%。不同外加碳源比较,相同浓度下投加剩余污泥发酵液比葡萄糖作为外加碳源脱氮效果好,其中发酵液为碳源时TN的平均去除率比葡萄糖作为碳源,TN去除率提高7.2%。当发酵液浓度COD为150mg/L,反应器的脱氮效率和COD去除率均较高,此时TN和COD的去除率为82.8%和89.4%。与空白对照组相比,添加适量的外加碳源后,出水荧光峰没有发生改变,荧光强度基本与空白对照组相似,说明明添加一定量的反硝化外加碳源后,出水有机物浓度并没有明显的提高,有机物的去除率没有受到明显影响。
[Abstract]:At present, the utilization of anaerobic fermentation broth from municipal wastewater treatment plant is one of the hotspots in environmental research. A large number of organic compounds (such as proteins, carbohydrates, volatile fatty acids) and ammonia nitrogen and orthophosphate are produced during the fermentation of excess sludge. However, the fermentation broth contains a high concentration of nitrogen and phosphorus. If the nitrogen and phosphorus are not removed and directly added to the sewage treatment structure, the sewage treatment load will be increased and the biological nitrogen removal efficiency will be affected. Sucrose simulated wastewater was used to study the anaerobic fermentation process of organic matter. The effect of organic loading on VFA accumulation in anaerobic methanogenic process was studied. The spectra of anaerobic methanogenic fermentation broth were analyzed by parallel factor method to determine the fluorescent substances and VFA accumulation in the fermentation broth under organic loading. The results showed that the fluorescent substances of the reactor were protein, coenzyme NADH and coenzyme F420. When the substrate concentration of the reactor suddenly increased, the fluorescence spectra of the effluent of the reactor also changed. The fluorescence intensity of coenzyme F420 decreased significantly. The main fluorescent components in the effluent of the reactor were tryptophan, tyrosine and coenzyme NADH, indicating the production of tryptophan, tyrosine and coenz With the increase of substrate concentration, COD and sucrose concentration of the effluent increased significantly first and then decreased gradually, VFA concentration increased first and then stabilized. After stabilization, the VFA concentration of the reactor was maintained at about 360mg/L. COD and VFA could not be degraded. After the inhibition was removed, the methanogenesis ability was restored, the concentration of COD and sugar decreased, and the concentration of VFA tended to be stable. Secondly, the release characteristics of cell substances during the fermentation of excess sludge were characterized by comparing the alkali and non-alkali conditions, and the nitrogen and phosphorus in the fermentation products were recovered in the form of bird manure. The effects of pH, P/N, Mg/P on the formation of bird manure stone were studied, and the optimum technological conditions were determined. In the experiment of nitrogen and phosphorus recovery, when p H=10, P/N=1.1 and Mg/P=1.5, the efficiency of nitrogen and phosphorus recovery was relatively high, and the recovery rates of nitrogen and phosphorus were 94.3% and 88.1%, 88.0% and 78.0%, 89.9% and 78.2% respectively. After recovery, the properties of the fermentation broth are similar to those of the anaerobic methanogenic reactor, so nitrogen and phosphorus can be recovered in the form of bird manure and added to the oxidation ditch reactor as an additional carbon source. The results showed that the denitrification effect of adding carbon source oxidation ditch process was significantly higher than that of blank control group, and the TN removal rate was 85.0% on average, 27.1% higher than that of blank control group. Compared with glucose as carbon source, the removal rate of TN was 7.2% higher when the fermentation broth was used as carbon source. When the concentration of COD was 150 mg/L, the removal efficiency of nitrogen and COD were both higher, and the removal rate of TN and COD was 82. 8% and 89.4%. Compared with the blank control group, the fluorescence peak of effluent did not change after adding appropriate amount of carbon source, and the fluorescence intensity was similar to the blank control group. It showed that the organic matter concentration of effluent did not increase significantly after adding a certain amount of denitrification and carbon source, and the removal rate of organic matter was not affected significantly.
【学位授予单位】：安徽建筑大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X703

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