环氧丙烷皂化废水活性污泥菌群利用污泥水解液合成PHA的研究

发布时间：2018-03-08 02:32

本文选题：活性污泥　切入点：挥发性脂肪酸(VFAs)　出处：《济南大学》2016年硕士论文　论文类型：学位论文

【摘要】：利用活性污泥中的混合菌群,以污泥厌氧酸化产生的水解酸化液作为培养基,生产生物可降解材料----聚羟基脂肪酸酯(PHA),对于工业生产产生的难处理的具有高盐度、高pH值等性质的污泥的减量化、资源化利用以及降低PHA合成成本并实现PHA的大规模生产具有重要意义。本论文首先探索了污泥厌氧消化产生水解酸化液的成分及含量。由于VFAs(挥发性脂肪酸)含量偏低,为保证研究环氧丙烷(PO)皂化废水活性污泥PHA的积累规律的稳定性与可靠性,后续实验中采用了模拟污泥水解酸化液作为基质,PO皂化废水活性污泥作为菌种,揭示了PO皂化废水活性污泥合成PHA与VFAs类型及消耗量间的关系,并探究了活性污泥菌群中PHA合成相关基因phaC与PHA积累的相关性。利用厌氧消化的方法,本论文分别探索了污泥在不同温度不同pH值条件下所产生的水解酸化液的VFAs种类、含量及其比例。所得到的VFAs主要为乙酸、丙酸、正丁酸三种,在最佳的条件(pH为5、温度为37°C)时,乙酸最高产量约为470 mg/L;三种VFAs的比例约为2:1:1。为进一步研究PO皂化废水活性污泥PHA的积累规律,采用了含有四种不同VFAs比例的模拟污泥酸化液作为基质,以PO皂化废水活性污泥作为菌种,进行小试生产PHA。结果表明:在乙酸:丙酸:正丁酸=2:1:1的条件下,PHA产量及VFAs消耗速率处于最佳水平,其中PHA的产量可达污泥干重的24.2%。之后采用最佳比例配制模拟酸化液,在反应器中进行批式发酵,结果表明:在16 h时PHA产量达到最大值,约为污泥干重的25.0%;通过单体比例分析,偶数碳原子数的VFAs有利于3HB的合成,奇数碳原子数的VFAs有利于3HV的合成。利用实时荧光定量PCR,发现了PO皂化废水活性污泥生产PHA的产量与phaC的表达量呈正相关性。本论文的研究工作将为实验室实现规模化生产PHA奠定基础,同时对于通过PHA生产过程中补料的控制获得高产PHA以及PHA合酶的活性研究等都具有一定的参考价值。
[Abstract]:Using mixed bacteria in activated sludge and hydrolytic acidizing liquid produced by anaerobic acidification of sludge as the medium, the biodegradable material, polyhydroxyfatty acid ester (PHAA), is produced with high salinity for the difficult treatment produced by industrial production. Reduction of sludge with high pH value and other properties, It is of great significance to reuse PHA and reduce the cost of synthesis and realize the large-scale production of PHA. In this paper, the composition and content of hydrolytic acidification solution produced by anaerobic digestion of sludge were explored. In order to ensure the stability and reliability of PHA accumulation in saponification wastewater of propylene oxide (PO) saponification wastewater, simulative sludge hydrolysate acidification solution was used as substrate for the subsequent experiment. The relationship between the type and consumption of PHA and VFAs in activated sludge synthesis from PO saponification wastewater was revealed, and the correlation between phaC and PHA accumulation of PHA biosynthesis gene in activated sludge flora was explored. The anaerobic digestion method was used. In this paper, the VFAs type, content and proportion of hydrolytic acidifier produced by sludge at different temperature and pH were studied. The VFAs obtained was mainly acetic acid, propionic acid, n-butyric acid. Under the optimum conditions of pH 5 and temperature 37 掳C, the maximum yield of acetic acid was about 470 mg / L and the ratio of three kinds of VFAs was about 2: 1: 1.In order to further study the accumulation of PHA in activated sludge of PO saponification wastewater, The simulated sludge acidification solution with four different VFAs ratios was used as the substrate, and the activated sludge from PO saponification wastewater was used as the strain. The results showed that under the condition of acetic acid: propionic acid: n-butyric acid 2: 1: 1, the yield and VFAs consumption rate of PHA were at the optimum level, and the output of PHA could reach 24.2wt of the dry weight of sludge, and then the simulated acidizing liquid was prepared in the best proportion. Batch fermentation was carried out in the reactor. The results showed that the PHA yield reached the maximum value at 16 h, which was about 25.0% of the sludge dry weight, and the even carbon atom number VFAs was favorable to the synthesis of 3HB by monomer ratio analysis. VFAs with odd number of carbon atoms is propitious to the synthesis of 3HV. By using real-time fluorescence quantitative PCRs, it is found that the yield of PHA produced by activated sludge from PO saponification wastewater is positively correlated with the expression of phaC. The research work in this paper will be realized in laboratory. Lay the foundation for large-scale production of PHA, At the same time, it has certain reference value for obtaining high yield PHA and studying the activity of PHA synthase through the control of feedstock in the process of PHA production.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X703;X172

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