Study On The Cleaner Production Of Itaconic Acid

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.