【摘要】：隨著城市化進(jìn)程的發(fā)展和人民生活水平的不斷提高,對(duì)水的需求量也一直呈加速上升趨勢(shì),污水處理廠(chǎng)的工作負(fù)荷越來(lái)越大,產(chǎn)生的剩余污泥也越來(lái)越多。剩余污泥的含水率很高,因此污泥脫水是處理污泥中的一道重要環(huán)節(jié)。降低污泥中的EPS含量,破壞其絮體結(jié)構(gòu),釋放其中的有機(jī)質(zhì)和水分,將對(duì)提高污泥的脫水性能起到積極的作用。固定化酶具有易回收、易儲(chǔ)藏、可降低成本等優(yōu)勢(shì),但游離酶的活性很容易受到反應(yīng)體系中的p H、溫度、離子濃度等因素的影響,可能會(huì)使部分游離酶失活,導(dǎo)致固定化酶酶活降低。目前主流的酶固定化載體有氧化石墨烯、殼聚糖、高分子聚合物,凝膠載體,多孔活性炭,納米金剛石、介孔氧化硅以及玻璃珠等。但是這些載體在回收上存在困難,需要通過(guò)離心、沉降等復(fù)雜操作。因此,本研究中選用磁性材料作為載體,增強(qiáng)固定化酶的可回收性。但直接使用磁性Fe3O4細(xì)顆粒很難實(shí)現(xiàn)對(duì)生物分子高效穩(wěn)定的固定。故還需要在磁性顆粒表面包覆纖維素,這樣一方面改善了細(xì)顆粒的分散性和相容性;另一方面改變了細(xì)顆粒的表面活性,增加了可供交聯(lián)的活性基團(tuán)。本課題選用纖維素基磁性納米顆粒作為載體,以戊二醛作為交聯(lián)劑,利用醛基與蛋白質(zhì)中的氨基能夠通過(guò)耦合實(shí)現(xiàn)穩(wěn)定交聯(lián),制作可磁力回收的固定堿性蛋白酶和α-淀粉酶酶,實(shí)現(xiàn)酶的回收,降低酶水解污泥的生產(chǎn)成本。通過(guò)考察固定化酶在不同條件下的酶活性和酶固載率來(lái)考察fe3o4的固載效果。之后通過(guò)比較污泥水解前后的cod、nh4+-n、還原糖、vss、tss等多項(xiàng)指標(biāo)來(lái)考察其水解污泥的實(shí)際效果。具體研究?jī)?nèi)容如下:(1)使用水熱合成法制備微米級(jí)的磁性fe3o4顆粒,并在其表面包覆纖維素以增加可交聯(lián)的活性基團(tuán)。將制備好的磁性顆粒作為固載酶的載體。通過(guò)vsm、sem、xrd等方法,對(duì)磁性fe3o4顆粒進(jìn)行表征。結(jié)果表明所制備的fe3o4為粒徑在0.8-4μm之間,球形圓滑,具有超順磁性的磁性細(xì)顆粒。(2)以磁性顆粒為載體,用戊二醛交聯(lián)法分別制備固定化堿性蛋白酶和固定化淀粉酶。結(jié)果表明在溫度為25℃,ph值為8,酶用量為600μl,戊二醛濃度為2%,交聯(lián)時(shí)間4h,吸附時(shí)間1h,固定化堿性蛋白酶和淀粉酶擁有最佳的酶活68.71%和67.51%。(3)將在最佳條件下制備的固定化酶用于催化水解剩余污泥。通過(guò)檢測(cè)scod/tcod、vss去除率、氨氮濃度變化和還原性糖濃度變化等指標(biāo),研究固定化酶對(duì)污泥的催化水解效果。結(jié)果在使用堿性蛋白酶催化水解后,scod/tcod比值上升了19.1%,vss去除率為27.4%,還原性糖濃度上升了26.7mg·g-1,氨氮濃度上升了58.4 mg·L~(-1);在使用堿性蛋白酶催化水解后SCOD/TCOD比值上升了25.4%,VSS去除率為35.3%,還原性糖濃度上升了37.3mg·L~(-1),氨氮濃度上升了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 偽 -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，

本文編號(hào)：2390280