【作者】 李丕武；

【导师】 陈西广；

【作者基本信息】 中国海洋大学 ， 海洋生物学， 2008， 博士

【摘要】 根据现有衣康酸生产的现状和我国清洁生产相关的法律法规,建立了衣康酸清洁生产的指标评价体系,并以此为依据对现有衣康酸生产的工艺首次从清洁生产的角度进行了系统的研究,找出现有工艺中存在的问题,分析问题产生的原因,并提出衣康酸清洁生产工艺改进的方案,本研究沿着先从实验室研究规模入手得到相关的基础数据,再以此为依据逐步扩大实验规模直至在大规模生产中取得应用,通过三年的研究与实践,其中的多项研究成果已经在生产中得到应用,并取得了良好的效果。具体研究结果如下:1、衣康酸清洁生产的必要性《中华人民共和国清洁生产促进法》对清洁生产的定义为:“不断采取改进设计、使用清洁的能源和原料、采用先进的工艺技术与设备、改善管理、综合利用等措施,从源头削减污染,提高资源利用效率,减少或者避免生产、服务和产品使用过程中污染物的产生和排放,以减轻或者消除对人类健康和环境的危害。”从中可以看出,清洁生产是循环经济在企业层次的具体体现,它已不是单纯的环保技术问题,而是谋求解决人类社会和自然和谐共存的大问题。国外清洁生产的实践证明了清洁生产作为污染防治战略的重要手段,是对传统的末端治理手段的根本变革。我国的资源利用率与发达国家相距甚远,高消耗是造成重污染的根源,也成为制约工业生产经济效益的基本原因。我国衣康酸规模化生产始于20世纪90年代初,随着衣康酸产能的不断提高,企业的竞争日趋激烈,改进工艺、降低成本成为衣康酸生产企业实施清洁生产工艺改造的内部动力;从宏观角度考虑,开展清洁生产,推进节能降耗符合目前国家倡导的循环经济、可持续发展的精神,这成为从外部推动企业进行衣康酸的清洁生产的动因;由于衣康酸产品绝大部分出口,国外衣康酸用户在考查衣康酸产品的质量的同时也对越来越多地关注到产品的生产过程是否符合清洁生产的要求,因此,从客户要求的角度考虑,开展衣康酸的清洁生产也迫在眉睫。我国的生物化工行业在节能降耗方面一直缺乏比较系统的研究,尽管衣康酸工业化生产在我国开展较晚,但目前采用的生产工艺中仍是借鉴传统发酵产业的操作单元,没有从节能降耗、原料的最有效利用及废物综合治理等清洁生产角度开展深入地研究,因此需要对现有衣康酸生产工艺的全过程进行系统的研究,使现有工艺水平有一个大的提升,概括地讲需要解决提高原料的利用率、降低产品的能耗、减少废水及废渣的排放并对产生的污染物进行综合治理三个层面的问题。2、衣康酸清洁生产评价体系的建立清洁生产评价体系是评价企业清洁生产的重要基础,对于推动可持续发展战略的实施具有重要的意义。目前国内清洁生产评价方法不够完善和规范,尤其在生物化工领域一直没有系统的清洁生产评价体系的建立,因此,本研究参照已有的其它行业的清洁生产评价体系的规范,结合衣康酸生产工艺的现状,建立衣康酸清洁生产的评价体系,为生物化工领域清洁生产的规范化提供依据。衣康酸清洁生产体系分成原材料指标、资源指标、污染物产生指标及产品指标四个方面共十五个单项指标。为了便于实施,建立各单项指标与不同的生产操作单元的联系,将衣康酸生产全过程分成糖化、发酵、提取、菌渣综合利用及衣康酸母液综合治理五个部分进行研究。3、衣康酸生产糖化工艺的改进.衣康酸生产中的淀粉制糖已经采用了双酶法制糖工艺,尽管现有工艺的水解程度可以达到98%以上,但从衣康酸发酵的结果来看,还有进一步改进的必要。由于生产中每次衣康酸发酵结束时,发酵液中总会有至少的残还原糖存在,这部分糖的存在,一方面降低了原料的利用率,另一方面会降低母液中衣康酸的提取率,增加污水治理的负荷。本研究依据脱支酶对淀粉分子的作用原理,对现有的糖化工艺进行改进,使发酵液中残糖的含量明显降低,有利于母液中衣康酸的提取,同时还缩短了糖化周期。4、衣康酸生产发酵工艺的改进发酵工序是衣康酸生产的关键,这一步实现了由原料向衣康酸的转化,生产菌株是完成这一步骤的主体。衣康酸生产菌为土曲霉(Aspergillus terreus),采用深层发酵培养方式。实现衣康酸发酵清洁生产工艺改进,关键是菌种水平的提高。本研究对衣康酸生产菌进行了过多步定向诱变,发酵产酸水平提高5%,发酵周期缩短了20小时,转化率提高3%以上;此外,对衣康酸发酵培养基配方进行了调整,降低了无机盐的加量,既减少了原材料的消耗,又减轻了后提取脱盐的负荷。5、衣康酸生产提取工艺的改进衣康酸的提取过程就是从发酵液中分离出各种杂质,最终得到精制衣康酸的过程,由一系列的操作单元组成,决定着衣康酸最终收率的高低。本研究从操作工艺和生产设备两方面对提出衣康酸提取工艺的清洁生产改进方案。改进了离子交换工艺,提高了母液质量并减轻了杂质阴离子对管道、设备的腐蚀;提出了浓缩冷凝水的回收和二次利用,大大降低了新水的消耗;活性炭的二次使用方案,可提高活性炭的使用效率,降低炭渣的总排放量;三效浓缩设备的应用使蒸汽消耗明显下降;真空转鼓过滤和卧螺式离心机的使用改善了生产操作的连续性,降低了工人的劳动强度;将膜过滤设备应用于衣康酸的提取中,对提高产品的质量起到了显著的改善作用。6、衣康酸发酵废菌丝体的综合利用菌丝体是衣康酸生产中固体废渣的主要来源,占发酵液的2%(W/V),由于适口性差,不能直接作为动物饲料,当前主要处理方式是锅炉烧掉或在空场堆放,对厂区环境造成严重污染。本研究从废菌体的化学成分分析入手,借鉴国内外的其它发酵行业的废菌体利用的经验,找出衣康酸废菌丝体的综合利用的途径。利用回收的树脂再生酸、碱从菌丝体中分离出甲壳素和菌体蛋白,提高的菌体的综合效益。7、衣康酸提取母液的综合治理方案由于衣康酸的提取采用的是重结晶法,因此,生产过程中会产生大量的母液,母液中除了含有衣康酸外,还含有残糖、无机离子及少量小分子胶质物质等,这些成分的浓度相对较高,抑制了母液中衣康酸的结晶和提取,导致这部分母液只能排放,不仅使衣康酸的提取率降低,也加重了污水处理的负荷。根据衣康酸母液的特点,本研究提出新的综合治理方案,首先采用离子交换树脂法使母液中的还原糖与衣康酸分离,再对树脂吸附的衣康酸洗脱后结晶提取,而含糖较多的流出液使用耐酸酵母处理,消耗其中的还原糖等,得到的菌体可作为蛋白饲料出售。8、本研究衣康酸清洁生产工艺的指标评价总结本研究对整个衣康酸各生产环节的清洁工艺改进方案,以年产5000吨衣康酸生产规模为例,按照先前建立的衣康酸清洁生产指标评价体系的要求,对原有衣康酸生产工艺和改进后的衣康酸清洁生产工艺进行了评分,累计分值分别为51.8和75.2分,这表明,原有衣康酸生产工艺从清洁生产角度考核属于相对落后行业,按照本研究清洁生产方案进行改进后,可使企业的清洁生产水平达到中等偏上的行列。更多还原

【Abstract】 In this study, an index evaluation system of itaconic acid (IA) was established according to the current situation of IA and the correlative laws in China. For the first time, a complete research on the IA production from this point of view was carried out, finding out the problems in the process of IA production, and then the project was advanced. All the research were begun with the data from laboratory and escalated to the industry scale. During the past three years, some of the work were applied successfully to industry. The details were shown below:1、The importance of the cleaner production of IA“The accelerate law of cleaner production of China”give the define of cleaner production as: to improve on design continuously, use cleaner energy and resource, use advanced technique and equipment, amend management and reuse method, cut the pollution from the headstream, enhance the efficiency of resource, reduce or avoid the drainages in the course of production, decrease the damage to people’s health and environment. It can be seen that the cleaner production is the embodiment of recycle economy in corporation level. It is not only belong to the issue of environment production but also to the exist of people and nature harmoniously. It has been testified from other country’s practice that the cleaner production is an important method to prevent pollution, it is far different from end repair. The reason for the low efficiency of resource in our country is high consume, which has prevent the development of industry. The industrial production of IA in our country was begun from 1990s, with the increase of production, the competition between company become fury. They have to improve their techniques in order to decrease the cost; In macro point of view, the cleaner production accord with the demand of our country’s policy of recycle economy, this can also push the step of cleaner production from outside of the company; For most IA is exported, overseas customer are taking more attention to the IA cleaner production and the IA company have to progress their cleaner production for this reason. For the lack of complete research of reducing energy and resource consume in the field of biochemistry in our country and many process used for reference from the conventional fermentation industry, no research on the process of IA was carried to reduce energy and resource consume and increase the efficiency of resource and say nothing of comprehensive treatment of castoff, even as the IA industry began more later than many other conventional fermentation industry. So it is urgent need to study the IA process with the point of view of cleaner production, in brief, including three aspects: increasing the efficiency of resource, reducing the energy consume, avoiding and treating with the drainage.2 The establishment of the index evaluation system of cleaner production of IAThe index evaluation system is an important means to evaluate the cleaner production of company and to promote the strategy of continually development. Currently, the evaluation of internal cleaner production is not complete and standard, especially in biochemical industry, in this study we refer to the criterion in other field and establish the evaluation system of cleaner production taking into account of the IA production. Our study would provide a pattern of cleaner production in the field of biochemistry.The cleaner production system of IA is divided into four aspects: the raw material index, the resource index, the drainage index and the product index. The amount of single index is fifteen. We found the relationship between the single index and the different steps of the IA process, including five parts as: saccharification, fermentation, recovery, comprehensive utilization of mycelium and the treat with mother liquor.3 The improvement of saccharification of IA processThe method for the corn starch catalyzing is a dual-enzyme. Although the scale of catalyzing is higher than 98%, more study has to be carried out when it is utilized into IA fermentation. When the fermentation was ceased each time, there always about 5～10g/l reducing sugar in the fermentation broth, which not only reduced the efficiency of feedstock, but also prevent the recovery of IA from the mother liquor. In this study, the debranch enzyme was used in the saccharification. As a result, the residue sugar of fermentation broth decreased distinctly. Further more, the time of saccharification was shortened.4 The improvement of fermentation of IA processFermentation is a key step of IA production, it realize the transform from sugar to IA, the important role of fermentation is the strain(Aspergillus terreus) for IA production. The strain is cultivate with the submerged fermentation method. To improve the quality of the strain, several site directed mutagenesis was used. As a result, the amount of IA in fermentation broth raised about 5%, the time of fermentation was shortened 20 hours, the yield of IA increased 3%; further, we controlled the composition of fermentation medium, reducing the amount of inorganic salts.5 The improvement of recovery method of IA processThe recovery process of IA is composed of several separation steps, it determines the ratio of IA recovery. In this study, we bring the improvement project on the recovery process and equipment. A more efficiency ion exchange process was advanced to lighten the corrosion of pipe and equipment. The evaporated water from condensation step was collected and reused to saving the water consume. The active carbon was also used twice. Triple effect evaporation can reduce the consume of steam obviously. The usage of the vacuum rotation drum filter and horizontal centrifuge enhance the continuity of operation and ease the labor force. Membrane filtration is also used to polish up the quality of IA product.6 The comprehensive utilization of myceliumThe amount of mycelium is very large among solid waste residue, it is about 2%(W/V) to fermentation broth. Because of the bad smell, it can’t be used as feedstuff for animal directly, it is burn out in boiler or picked up in the barnyard, which bring badly effect to the environment. In this study, we analyzed the compound of mycelium and used for reference of other researchers, a path of comprehensive utilization was proposed. We can get chitin and protein from the mycelium using the waste alkali and waste hydrochloric acid, so as to enhance its comprehensive benefits.7 The project of the comprehensive treatment of the mother liquorFor the reason of recrystallization, a large amount of mother liquor were produced with the production of IA, except for IA, it also contain residua sugar, mineral and colloid, which could prevent the recovery of IA crystal. The drainage of the mother liquor would not only reduce the extraction of IA but also increase the load of sewerage treatment. So a comprehensive treatment was proposed in this study. Firstly, the residua sugar and IA was separated by ion exchange, secondly, the IA absorb by the resin was washed out to recovery the IA, the residua mother liquor was treated with yeast to consume the residua sugar in it. The yeast should be collected at last for sale as feedstuff.8 The index evaluation of cleaner production of IA to this studyCompared the conventional and progressed process of IA production with the example of the scale of production of IA 5000t/y, the grades were 51.8 and 75.2, respectively. It indicate that the progressed process can raise the cleaner production of IA process to a higher level.更多还原