游离酶固定化及其水解污泥效果研究
发布时间：2018-12-24 06:44
【摘要】：随着城市化进程的发展和人民生活水平的不断提高,对水的需求量也一直呈加速上升趋势,污水处理厂的工作负荷越来越大,产生的剩余污泥也越来越多。剩余污泥的含水率很高,因此污泥脱水是处理污泥中的一道重要环节。降低污泥中的EPS含量,破坏其絮体结构,释放其中的有机质和水分,将对提高污泥的脱水性能起到积极的作用。固定化酶具有易回收、易储藏、可降低成本等优势,但游离酶的活性很容易受到反应体系中的p H、温度、离子浓度等因素的影响,可能会使部分游离酶失活,导致固定化酶酶活降低。目前主流的酶固定化载体有氧化石墨烯、壳聚糖、高分子聚合物,凝胶载体,多孔活性炭,纳米金刚石、介孔氧化硅以及玻璃珠等。但是这些载体在回收上存在困难,需要通过离心、沉降等复杂操作。因此,本研究中选用磁性材料作为载体,增强固定化酶的可回收性。但直接使用磁性Fe3O4细颗粒很难实现对生物分子高效稳定的固定。故还需要在磁性颗粒表面包覆纤维素,这样一方面改善了细颗粒的分散性和相容性;另一方面改变了细颗粒的表面活性,增加了可供交联的活性基团。本课题选用纤维素基磁性纳米颗粒作为载体,以戊二醛作为交联剂,利用醛基与蛋白质中的氨基能够通过耦合实现稳定交联,制作可磁力回收的固定碱性蛋白酶和α-淀粉酶酶,实现酶的回收,降低酶水解污泥的生产成本。通过考察固定化酶在不同条件下的酶活性和酶固载率来考察fe3o4的固载效果。之后通过比较污泥水解前后的cod、nh4+-n、还原糖、vss、tss等多项指标来考察其水解污泥的实际效果。具体研究内容如下:(1)使用水热合成法制备微米级的磁性fe3o4颗粒,并在其表面包覆纤维素以增加可交联的活性基团。将制备好的磁性颗粒作为固载酶的载体。通过vsm、sem、xrd等方法,对磁性fe3o4颗粒进行表征。结果表明所制备的fe3o4为粒径在0.8-4μm之间,球形圆滑,具有超顺磁性的磁性细颗粒。(2)以磁性颗粒为载体,用戊二醛交联法分别制备固定化碱性蛋白酶和固定化淀粉酶。结果表明在温度为25℃,ph值为8,酶用量为600μl,戊二醛浓度为2%,交联时间4h,吸附时间1h,固定化碱性蛋白酶和淀粉酶拥有最佳的酶活68.71%和67.51%。(3)将在最佳条件下制备的固定化酶用于催化水解剩余污泥。通过检测scod/tcod、vss去除率、氨氮浓度变化和还原性糖浓度变化等指标,研究固定化酶对污泥的催化水解效果。结果在使用碱性蛋白酶催化水解后,scod/tcod比值上升了19.1%,vss去除率为27.4%,还原性糖浓度上升了26.7mg·g-1,氨氮浓度上升了58.4 mg·L~(-1);在使用碱性蛋白酶催化水解后SCOD/TCOD比值上升了25.4%,VSS去除率为35.3%,还原性糖浓度上升了37.3mg·L~(-1),氨氮浓度上升了60.2 mg·L~(-1)。
[Abstract]:With the development of urbanization and the improvement of people's living standard, the demand for water has been increasing rapidly. The working load of sewage treatment plant is increasing, and the excess sludge produced is more and more. The water content of excess sludge is very high, so sludge dewatering is an important link in sludge treatment. Reducing the content of EPS, destroying the floc structure and releasing organic matter and moisture in sludge will play a positive role in improving the dewatering performance of sludge. The immobilized enzyme has the advantages of easy recovery, easy storage and low cost. However, the activity of free enzyme is easily affected by the factors such as pH, temperature and ion concentration in the reaction system, which may result in partial inactivation of free enzyme. The enzyme activity of immobilized enzyme was decreased. At present, the main enzyme immobilized carriers are graphene oxide, chitosan, polymer, gel carrier, porous activated carbon, nanocrystalline diamond, mesoporous silica and glass beads. However, these carriers are difficult to recover and need complex operations such as centrifugation and sedimentation. Therefore, magnetic materials were chosen as carrier in this study to enhance the recoverability of immobilized enzymes. But it is difficult to immobilize biomolecules efficiently and stably with magnetic Fe3O4 particles directly. Therefore, it is necessary to coat cellulose on the surface of magnetic particles, which not only improves the dispersion and compatibility of fine particles, but also changes the surface activity of fine particles and increases the active groups available for crosslinking. In this paper, cellulose based magnetic nanoparticles were chosen as carrier, glutaraldehyde as crosslinking agent, and aldehyde group and amino group in protein were used to realize stable crosslinking by coupling. Magnetic recovery of fixed alkaline protease and 伪 -amylase was made to realize the recovery of enzyme and reduce the production cost of enzymatic hydrolysis sludge. The immobilization effect of fe3o4 was studied by studying the enzyme activity and immobilized rate of immobilized enzyme under different conditions. After that, cod,nh4-n, reducing sugar, vss,tss and other indexes before and after sludge hydrolysis were compared to investigate the actual effect of sludge hydrolysis. The main contents are as follows: (1) Micron magnetic fe3o4 particles were prepared by hydrothermal synthesis and coated with cellulose to increase cross-linking active groups. The prepared magnetic particles were used as the carrier of the enzyme. Magnetic fe3o4 particles were characterized by vsm,sem,xrd. The results show that the prepared fe3o4 is a fine magnetic particle with spherical and smooth spherical size ranging from 0.8-4 渭 m. (2) the magnetic particle is used as the carrier. Immobilized alkaline protease and immobilized amylase were prepared by glutaraldehyde crosslinking method. The results showed that the temperature was 25 鈩，
本文编号：2390280
[Abstract]:With the development of urbanization and the improvement of people's living standard, the demand for water has been increasing rapidly. The working load of sewage treatment plant is increasing, and the excess sludge produced is more and more. The water content of excess sludge is very high, so sludge dewatering is an important link in sludge treatment. Reducing the content of EPS, destroying the floc structure and releasing organic matter and moisture in sludge will play a positive role in improving the dewatering performance of sludge. The immobilized enzyme has the advantages of easy recovery, easy storage and low cost. However, the activity of free enzyme is easily affected by the factors such as pH, temperature and ion concentration in the reaction system, which may result in partial inactivation of free enzyme. The enzyme activity of immobilized enzyme was decreased. At present, the main enzyme immobilized carriers are graphene oxide, chitosan, polymer, gel carrier, porous activated carbon, nanocrystalline diamond, mesoporous silica and glass beads. However, these carriers are difficult to recover and need complex operations such as centrifugation and sedimentation. Therefore, magnetic materials were chosen as carrier in this study to enhance the recoverability of immobilized enzymes. But it is difficult to immobilize biomolecules efficiently and stably with magnetic Fe3O4 particles directly. Therefore, it is necessary to coat cellulose on the surface of magnetic particles, which not only improves the dispersion and compatibility of fine particles, but also changes the surface activity of fine particles and increases the active groups available for crosslinking. In this paper, cellulose based magnetic nanoparticles were chosen as carrier, glutaraldehyde as crosslinking agent, and aldehyde group and amino group in protein were used to realize stable crosslinking by coupling. Magnetic recovery of fixed alkaline protease and 伪 -amylase was made to realize the recovery of enzyme and reduce the production cost of enzymatic hydrolysis sludge. The immobilization effect of fe3o4 was studied by studying the enzyme activity and immobilized rate of immobilized enzyme under different conditions. After that, cod,nh4-n, reducing sugar, vss,tss and other indexes before and after sludge hydrolysis were compared to investigate the actual effect of sludge hydrolysis. The main contents are as follows: (1) Micron magnetic fe3o4 particles were prepared by hydrothermal synthesis and coated with cellulose to increase cross-linking active groups. The prepared magnetic particles were used as the carrier of the enzyme. Magnetic fe3o4 particles were characterized by vsm,sem,xrd. The results show that the prepared fe3o4 is a fine magnetic particle with spherical and smooth spherical size ranging from 0.8-4 渭 m. (2) the magnetic particle is used as the carrier. Immobilized alkaline protease and immobilized amylase were prepared by glutaraldehyde crosslinking method. The results showed that the temperature was 25 鈩，
本文编号：2390280
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