KR19990000420A - Low-pollution snow removing agent using organic waste and lime and its manufacturing method - Google Patents

Abstract

The present invention relates to a method for preparing calcium magnesium salt (CMO) of an organic acid as a new snow removing agent for reducing the environmental pollution by the currently used snow removing agent NaCl and CaCl ₂ .

CMO is a chemical compound consisting of a mixed salt of Ca, Mg, acetic acid and propionic acid, and is a new low-pollution snow remover with ice-like effect similar to salt and much less corrosive. However, since the current production cost is high and the mass production is not made, in the present invention, in order to reduce the production cost of the CMO, sugar or fermentable by hydrolysis is generated from the organic waste, and the organic acid is produced after fermentation of bacteria, or Ca or The objective was to develop a process for preparing mixed salts by reacting with calcite containing Mg. In addition, it is possible to further reduce costs by mass production of organic acids in a short time using a continuous fermentation process.

Diluted organic waste containing food waste, food factory sludge, dairy factory sludge, livestock meal, by-products generated after processing agricultural products, sawdust, wood chips, starch, fiber, hemicellulose, lactose, sulfuric acid, hydrofluoric acid, acetic acid, etc. Fermentable sugars such as glucose and xylose are produced by hydrolysis using enzymes such as acids, amylases and cellulase as catalysts. Fermentation process including batch fermentation, fed-batch culture fermentation, continuous fermentation, cell recirculation continuous fermentation, and fixed cell fermentation using organic acid-producing bacteria Propionibacterium acidipropionici or Clostridium thermoaceticum with sugar produced by hydrolysis as carbon source After producing acetic acid and propionic acid through, the organic acid diluted in the fermenter is concentrated by a liquid-liquid separation process using trioctylphosphine oxide (TOPO) or trioctylamine as a solvent, or membrane separation process by ultrafiltration or reverse osmosis.

CMO, a mixed salt, is formed by adding calcium and magnesium containing lime, such as sludge produced during the production of hydrated lime, quicklime, and soda ash, and sludge produced after water purification in a water treatment plant To produce a low pollution snow removal agent.

Description

Low-pollution snow removing agent using organic waste and lime and its manufacturing method

The present invention relates to a method for preparing calcium magnesium salt of organic acid (CMO), which is a low pollution snow removal agent from organic waste and calcification using physicochemical and biological methods.

Organic wastes such as food waste, livestock manure, and by-products generated during processing of food and forest products are collected in small units around the source and used for livestock feed or composted and re-introduced into the farmland. However, the collection process is not scientific, so the complete collection is not made, and part of it is discharged to sewage, so that it is permeated into rivers or groundwater and contaminates various water resources. In addition, many of them are left unattended on the ground for the maturation of compost, which is damaging the surrounding landscape and causes various environmental pollution problems such as damaging the neighboring settlements by the odor. As part of efforts to reduce the pollution caused by such wastes and to recycle resources, active researches are being conducted at home and abroad, including fertilizing wastes and fueling methane gas generated by anaerobic bacteria. However, the products produced by these methods are not effective because of their low added value as commodities and their overall energy balance (input energy vs output energy).

See Alter, H., Energy Equivalents, Science, 189 (1975): Fan, L.T., M.M. Gharpuray, and Y.H. Lee, Cellulose Hydrolysis, Biotechnol. Monographs vol. 3, Springer-verlag, NY (1987). Organic waste, unlike industrial wastewater and waste, has a low content of heavy metals and toxic compounds, and is rich in renewable nutrients, so it is reused as a feedstock for bacteria and commercially available end-product. Can produce Bisaria. V.S., Bioconversion of Agro-residues to Glucose and Chemicals, in: Bioconversion of Waste Materials to Industrial Products, Martin, A.M. Ed., Elsevier Appl. Sci., 187-223, London, UK (191).

Currently, the most widely used snow removing agent in the world includes salt (NaCl) and calcium chloride (CaCl ₂ ), and the amount of spraying on highways and bridges reaches 8 million tons annually in the United States alone. About 5000 tons are used annually for snow removal. However, the massive spread of these chemicals containing chlorine ions (Cl) has caused serious corrosion and environmental pollution. The separation of cement and chlorine ions causes the destruction of concrete buildings around the road and serious damage to property and property such as corrosion of bridges and automobiles, corrosion of wire cables and water pipes and underground pipes. It melts in water and flows into rivers and lakes, causing a variety of environmental problems, including the destruction of aquatic ecosystems, pollution of drinking water, and damage to plants around roads.

The low-emission snow removal agent for snow removal and ice making which the present invention intends to manufacture refers to a mixed salt of Ca, Mg, acetic acid, and propionic acid as a calcium magnesium salt (CMO) of an organic acid. CMOs are similar to salts in ice making by the freezing point drop and are much less corrosive. After dissolving in water, Ca and Mg settle in the ground, turning into soil nutrients, and organic acids (acetic acid and propionic acid) are biodegraded by bacteria, so there is little risk of environmental pollution. The US Department of Transportation already stipulates a law restricting the use of existing snow removers, including salt, and uses magnesium magnesium acetate (CMA) as an alternative snow remover for several weeks, including California and Washington. Many effects have been demonstrated, including much less ambient corrosion and less bleaching of paint applied to road floors and buildings accelerated by salt. Harrach, N. and J. Wyatt, Fine Tuning CMA for Corrosion Control , Public Works, 121, 40-41 (1990); Anon, Oklahoma DOT Uses CMA in Freezing Rain, Public Works, 122, 55-57 (1991)], but despite these results, mass production has not yet taken place due to high production costs. Salt, calcium chloride and CMA are mixed from 8: 2 to 7: 3. The net price is currently $ 600 per tonne, or 27 times the price of salt of equal weight, and more than 80% of this price is due to the value of raw materials such as acetic acid, Ca and Mg [Chollar, BH, Federal Highway Administration, Research]. on Calcium Magnesium Acetate-an Alternative Deicer. Public Roads, 47, 113-118 (1984): McCrum, R.L., Corrosion Evaluation of Calcium Magnesium Acetate (CMA), Salt (NacL), and CMA / Salt Solutions, National Association of Corrosion Engineers Corrosion / 89, Paper No. 127, New Orleans, Louisiana, April (1989). Conventional organic acids have been synthesized from petroleum or natural gas, and these synthetic organic acids are not only expensive, but also cannot produce a sufficient amount to meet mass consumption.

1 is a diagram showing the conversion to glucose when starch is hydrolyzed using sulfuric acid as a catalyst at 132 ℃.

Figure 2 is a curve showing the production rate of organic acid and dry cell mass when batch fermentation is performed using bacterial propionibacterium ash propioniti (Propionibacterium acidipropionici) and glucose as a carbon source.

Figure 3 is a curve showing the production rate of organic acid and dry cell volume when batch fermentation was carried out using the bacteria Propionibacterium apidipropioni and xylose as a carbon source.

Figure 4 shows the production rate of organic acid and dry cell volume when cell recycling continuous fermentation using bacterial propionibacterium acid propionii and carbon extracted from sugar, bakery waste and sawdust. curve.

The gist of the present invention is to produce a fermentable sugar by hydrolysis from organic waste to reduce the production cost of CMO, a new low-pollution snow removing agent, and to produce an organic acid through fermentation of bacteria, and then reacted with lime containing Ca or Mg and mixed salt It is a method for producing a, and also by using a continuous fermentation process can mass production of organic acids in a short time to further reduce the cost.

Looking at the process in detail, the process of hydrolysis of organic waste containing starch or fiber, such as food waste, livestock manure, by-products generated during food or forest products processing can be divided into two types: hydrolysis by enzymes and acid hydrolysis. Can be. Enzyme method is very specific and has the advantage of ensuring a high yield, but requires a pretreatment process of the raw material and has the disadvantage of increasing the process price due to the price of expensive enzyme. Moreover, it is not desirable for mass production except in the case of production of products requiring a long time and good quality due to the complex reaction process. The acid hydrolysis process can be further classified into high acid-low temperature process and low acid-high temperature process. When high concentration acid is used, the reaction takes place at low temperature (below 100 ℃). Hydrolysates can be obtained but are expensive to regenerate or neutralize the acids used. When using low concentration acid, it should be reacted at high temperature (above 180 ℃), and its advantages and disadvantages are roughly opposite to high concentration acid-low temperature process. Acid hydrolysis has the advantage of extracting sugars with a simpler and shorter reaction time than the enzyme process. In order to obtain a high yield, it is possible to use a high concentration of acid or to react at high temperature, but the purpose may be achieved by selectively extracting hydrolyzed sugars before they are decomposed. Most organic wastes contain various types of carbohydrates such as starch, fiber and hemi-fiber, and hydrolysis produces starch and fiber as glucose, which is hexasaccharide, and hemi-fiber as glucose and pentose, xylose. Among them, fibrous materials have stronger intermolecular energy than starch or hemifiber, requiring much stronger reaction conditions. By selectively hydrolyzing the materials with different reaction conditions using two different concentrations of sulfuric acid or reaction temperature at room temperature, it is possible to minimize the decomposition of generated sugars and to prevent product inhibition. .

Sugar obtained through hydrolysis is fermented by adding nutrients such as proteins and vitamins necessary for bacterial growth after proper pretreatment such as alkali neutralization and filtration purification. As the bacterial species to be used for fermentation, propionibacterium acidipropionici is selected to produce acetic acid and propionic acid simultaneously or to produce acetic acid using Clostridium thermoaceticum. C. thermoseticum is a high-temperature anaerobic bacterium that produces only acetic acid as a by-product. P. acidpropionici is an anaerobic bacterium that produces acetic acid and propionic acid in a ratio of approximately 1: 2 and produces more organic acids due to less energy consumed by respiration in the absence of oxygen. For mass production of organic acids, there are several methods such as fed batch, continuous, and immobilized cell fermentation. The fed-batch fermentation process is mainly used for aerobic bacteria as the growth rate of bacteria depends on the carbon source, and the maximum growth rate is maintained by increasing the amount of sugar at the time when the carbon source is exhausted. . However, since organic acid bacteria produce organic acids as secondary metabolites after maximal growth, this method, which can maintain maximum growth rate, can be seen as a very efficient way to increase organic acid production. The continuous fermentation process extracts products containing organic acids from the fermenter at the same rate while continuously introducing a carbon source at a constant dilution rate, thereby preventing starvation of microorganisms and minimizing product inhibition by the product. Cell recycling continuous fermentation, in particular, uses the cross-microfiltration method to recycle bacteria in the maximum growth state into the fermenter, thereby rapidly increasing the number of microorganisms in the fermenter, maximizing organic acid production and increasing the maximum concentration of organic acid. Can be produced continuously.

The organic acid produced through fermentation is diluted to a maximum of 2-3% in the culture medium, and among them, it contains various foreign substances such as microorganisms and medium solution. Should be used. The recovery of the oxides of organic acids or alcohols produced from fermenters is an important process that determines the economics of fermented products and has the greatest potential to save energy. . The unit operation process for selecting the desired substance from the diluent can be classified into three types: gas-liquid separation, liquid-liquid separation, and solid-liquid separation. Distillation, evaporation, extraction, This includes various separation processes such as adsorption, membrane separation, filtration, centrifugation, and the like. Each of these processes has its own advantages and disadvantages. Therefore, the most suitable process should be selected and used according to the nature of the raw materials to be separated. The criteria are mainly the degree of concentration, purity, and economic efficiency. As a unit process for the separation of organic acids, the distillation process was mainly used, but the energy consumption is high and the installation cost of the facility is excessive, and a number of membrane separation processes such as liquid-liquid separation, ultrafiltration, and reverse osmosis are gradually being attempted.

The organic acid diluted in the fermentor can be most effectively concentrated by liquid-liquid separation using an appropriate solvent. Trioctylphosphine oxide (TOPO) or trioctylamine can be used as the solvent for extracting the organic acid, and the organic acid can be selectively concentrated as a relatively small amount of solvent. Tertiary amine solvents generally have better selectivity than primary or secondary amines and the extraction effect improves as the number of carbon chains increases. The high degree of screening of these solvents also has the advantage of reducing facility and operating costs when scale-up in mass production. The membrane separation process is used to separate foreign substances in the solution according to the pore size of the membrane and is used for microfiltration, ultrafiltration, reverse osmosis, pervaporation, and electrodialysis. ) Are most commonly used in water treatment processes. The separation process is performed by the difference in the movable force of the flowing material through the membrane, and the main movable force is a hydraulic pressure difference, a potential difference, a vacuum force, and the like. Among the various membrane separation processes, ultrafiltration or reverse osmosis is widely used for the separation of organic substances in water, and in particular, reverse osmosis is operated by a simple physical pressure difference, so that no chemical reaction or potential change occurs and no energy is generated. It has the advantage of low consumption. On the other hand, whenever the membrane blockage occurs, the process must be stopped and backwashed, and since the desired material is not selectively separated, there is a disadvantage in terms of purity.

The concentrated organic acid is put into the snow removing process, and the salts of Ca, Mg and organic acid are added by adding substances including lime, such as sludge generated during the production of hydrated lime, quicklime, and soda ash, and sludge generated after the purification process in a water treatment plant. (CMO) is formed. The reacted salts are dried for several days at medium temperature and then re-powdered to produce a low pollution snow remover that can replace NaCl or CaCl ₂ .

In the following examples several process features of the invention will be illustrated.

Example 1

The organic waste containing a large amount of starch was hydrolyzed using an enzyme as a catalyst. First, the mixture is mixed with distilled water so that the solid content is 20%, and 0.3 ml of alpha-amylase (TAKA-THERM) is added to about 600 g of the pH-adjusted mixture, and the reaction is continued at 90 ° C. for 1 hour. I was. Subsequently, the pH was readjusted and 0.9 ml of glucoamylase (Diazyme L-200) was added, followed by hydrolysis at 60 ° C. for 4 hours under stirring. As shown in Table 1, the conversion of starch to fermentable sugar was very good (94-96%) when hydrolyzing two kinds of grain dust and baking and cake wastes generated during the grain processing.

TABLE 1

Sugar Conversion Rate by Enzymatic Hydrolysis of Organic Wastes

* Sugar conversion rate = (fermentable sugar production ÷ 1.1) ÷ starch content (including sugar) × 100

Example 2

Pure starch and cotton fiber extracted from wheat were subjected to acid hydrolysis with sulfuric acid and hydrochloric acid. The sample was mixed with distilled water to make the solid component 15%, and hydrolysis was performed by modifying sulfuric acid or hydrochloric acid concentration and reaction time at the reaction temperature of 122 ° C. and 132 ° C. using supersaturated steam pressure. According to Figure 1 it can be seen that there is a time when the sugar production concentration reaches a peak at a constant reaction temperature and acid concentration, and before and after that time period, the sugar production concentration and recombination rate are not balanced and the sugar production concentration is lowered. When the pure starch is hydrolyzed to acid, as shown in Table 2, it can be seen that the optimum time for sugar yield is shortened when the reaction temperature is high or when hydrochloric acid is used, and the sugar conversion is generally high at 122 ° C. When used, it reached 91-94%. In the case of acid hydrolysis of cotton cellulose, the sugar conversion rate was lower than 30% as shown in Table 3. The optimum reaction time was shortened by increasing the reaction temperature or using hydrochloric acid, and the sugar yield was excellent at high concentrations using sulfuric acid and low concentrations using hydrochloric acid.

TABLE 2

Acid Hydrolysis Using Pure Starch

TABLE 3

Acid Hydrolysis Using Cotton Fiber

Example 3

As exemplified in Example 2, starch and fibrin can be regarded to have a large difference in reaction conditions and sugar conversion due to structural differences. However, since various organic wastes present in the natural environment are mixed with starch and fiber, the sugar conversion rate of one component is extremely low according to one reaction condition, and the overall efficiency is greatly reduced. In this experiment, two-step acid hydrolysis was performed to overcome this case. The first step was hydrolysis of starch-containing waste in the wastes for 2 minutes at 132 ° C using 2% sulfuric acid, and the second step was hydrolyzed at 132 ° C for 70 minutes with 15% sulfuric acid as the fiber-containing ones. It was. Table 4 shows the results of the two-step acid hydrolysis of bakery waste, sawdust, grain dust, and dense population as samples containing organic starch, fiber, starch, fiber, and hemi-fiber in combination. Each sample was found to minimize sugar re-degradation and efficiently converted to sugar through two-stage acid hydrolysis process. Baking waste was converted to sugar in 100g sample with 79g and other organic wastes were also 36-46g. It proved to be an excellent raw material for recycling.

TABLE 4

Two stage acid hydrolysis of organic waste (/ 100g sample per gram)

* One-stage hydrolysis condition is 40 minutes at 132 ℃ using 2% sulfuric acid solution

** Two-stage hydrolysis condition is 70 minutes at 132 ℃ using 15% sulfuric acid solution

Example 4

Batch fermentation was performed to test the organic acid production rate of bacterilla. The bacterial species were selected as Pronionibacterium asididipropionis and studied to simultaneously produce acetic acid and propionic acid in anaerobic conditions. Figure 2 shows the increase in organic acid and dry cell mass when glucose 19.1g / l as a carbon source and fixed at pH 6 and temperature 30 ℃. Acetic acid increased almost linearly from the beginning of fermentation, producing 5.7 g / l after about 120 hours, but propionic acid began to form after about 30 hours, reaching 8.5 g / l after 120 hours. The cell proliferation rapidly increased for about 20 hours when the glucose remaining in the fermentor was consumed and then increased very slowly after all the glucose was consumed, reaching 4.0 g / l after 132 hours. When xylose is used as the carbon source under the same bacteria and environmental conditions, the results are shown in FIG. 3. The production rate of acetic acid and propionic acid was similar to that of glucose fermentation, but the yield was low, acetic acid produced 3.8g / l after 100 hours and 5.4g / l after 65 hours. The maximum dry cell mass reached 3.7 g / l after 54 hours, but then slowly decreased by microbial aggregation and killing.

Example 5

Cell recycle continuous fermentation was performed for mass production of organic acids. The environmental conditions were set to pH 6 and temperature 30 ° C. as in the case of batch fermentation, and glucose was used as the carbon source for the first 5 days and then sugar (including glucose or xylose) extracted from baking waste and sawdust for 5 days, respectively. Figure 4 shows the cell volume recycled in the fermenter and the amount of organic acid contained in the effluent after the cell recycle continuous fermentation was fixed at a recycle rate of 0.1 h ^-1 and continuously operated for about 15 days. Dry cell volume increased continuously, reaching 34.4 g / l of glucose fermentation, 8.6 times higher than batch fermentation, and total organic acid production was almost the same as batch fermentation (0.77 g organic acid / g). Compared to 11 times. Dry cell and total organic acid production reached 30.8 g / l and 0.75 g organic acids / g, respectively, using sugars derived from baking waste (100% glucose), which were nearly identical to those of glucose. When sugar (including 14.3% glucose and 85.7% xylose) was used, it produced 25.3g / l and 0.53g organic acid / g sugar, which produced about 71% of pure glucose, but 86% of carbon sources were xyl. Considering that it was Ross, it showed great results.

Although the present invention has been described in detail through the foregoing embodiments, a person of ordinary skill in the art may add many variations and modifications within the spirit and scope of the present invention described in the detailed description of the present invention. And modifications are included within the scope of the present invention.

According to the manufacturing method of the low pollution snow removing agent of the present invention, not only significantly reduce the production cost of the low pollution snow removing agent, but also produce a fermentable sugar by hydrolysis from organic waste and form an organic acid through the fermentation of bacteria Ca or Mg It provides a novel method for producing mixed salts by reacting with calcareous containing, and in addition, it is possible to further reduce the production cost since the organic acid can be mass produced using a continuous fermentation process.

Claims (7)

Organic waste is produced by hydrolysis using acid or enzyme as a catalyst and acetic acid through fermentation using propionibacterium acidipropionici or Clostridium thermoaceticum. Calcium Magnesium Salt of Organic Acids (CMO) as a mixed salt by adding calcium and magnesium containing lime to the concentrated organic acid after the separation and production of propionic acid. A method for producing a low pollution snow removing agent. 2. The starch according to claim 1, wherein the sample for hydrolysis and fermentation is produced after processing of at least one raw material selected from the group consisting of food waste, food factory sludge, dairy factory sludge, ground wood, livestock meal and agricultural products. and organic waste containing at least one component selected from the group consisting of starch, cellulose, hemicellulose and lactose. The method according to claim 1, wherein the catalyst for hydrolysis is diluent acid containing sulfuric acid, hydrochloric acid, hydrofluoric acid and acetic acid or an enzyme including amylase and cellulase. The method of claim 1, wherein the fermentation process in the process of producing organic acid through fermentation is batch fermentation (fed batch fermentation), continuous fermentation (continuous fermentation), cell recycling continuous fermentation (cell) recycling continuous fermentation, immobilized cell fermentation. The method of claim 1, wherein the organic acid diluted in the fermenter is a liquid-liquid separation process or ultrafiltration or using trioctylphosphine oxide (TOPO) or trioctylamine as a solvent. Concentrated by membrane separation process by reverse osmosis. The method according to claim 1, wherein the calcium and magnesium-containing calcareous material comprises sludge generated during the production of hydrated lime, quicklime, and soda ash, and sludge generated after a water treatment process in a water treatment plant. A CMO low pollution snow removing agent prepared by the method according to any one of claims 1 to 6.