JP2000189183A - Production of biodegradable plastic from vegetable oil waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To treat organic components in a vegetable oil waste without generating methane gas during a disposal process for the vegetable oil waste and at the same time produce a useful component from the vegetable oil waste by using a hydrogen bacterium. SOLUTION: The organic components in a vegetable oil waste are converted into organic acids in a short time by subjecting the vegetable oil waste to an anaerobic treatment and stopping the reaction at the acid fermentation step without allowing the reaction to proceed to methane fermentation, subsequently sludge is separated and removed from the anaerobically treated liquid by a solid-liquid separation means such as centrifugation, and the organic acid- containing liquid prepared by the removal of the solid components is concentrated by using an ion-exchanging resin or by heating to obtain a concentrated organic acid liquid. Polyhydroxyalkanoate(PHA), which is a biodegradable resin, is produced from the concentrated organic acid liquid by a hydrogen bacteria.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a biodegradable plastic from a vegetable oil waste liquid, and more particularly, to a method for producing a biodegradable plastic from an organic acid produced by organic acid fermentation by hydrogen bacteria from an organic acid produced by organic acid fermentation. The present invention relates to a method for producing a certain polyhydroxyalkanoate (PHA).

[0002]

2. Description of the Related Art In the industry where palm oil is produced from coconut, a considerable amount of waste liquid containing oil is discharged at the same time as palm oil is collected. The effluent is usually put into a treatment lagoon called a lagoon, where it is treated by natural methane fermentation. However, the discharge of the effluent is increasing with the increase in palm oil production, which makes the treatment difficult. It has become to. In the industry that produces vegetable oil from soybeans and corn, wastewater containing organic substances such as oil is discharged, and its treatment is also a problem.

In recent years, a large amount of fats and oils have been consumed in meals at home with the westernization of daily life. In addition, the use of oils and fats has increased along with the prosperity of the delicatessen industry, in order to reduce the domestic labor associated with the prosperity of the restaurant industry and the housewife's advancement to the workplace. Furthermore, due to the boom in the cleanliness, morning shan and the like have become popular, and the amount of detergent used has been increasing steadily.
In addition, due to health consciousness, consumers are increasingly popular with vegetable fats and oils rather than animal fats in the diet, and synthetic detergents and vegetable detergents in the detergent category. In the diet,
In addition to soybean oil, rapeseed oil, olive oil and camellia oil as vegetable oils and fats, coconut oil (palm kernel oil) as margarine (artificial butter) is frequently used. In the field of detergents, coconut oil (palm oil) is frequently used as a raw material for soap. The treatment of these kitchen wastewaters is not sufficient with ordinary activated sludge treatment.

[0004] The contents of a conventional method for treating vegetable oil waste liquid will be briefly described by taking palm oil waste liquid treatment as an example. FIG. 6 shows a palm oil pressing process. According to this figure, 1 ton of coconut palm is used to prepare crude palm oil (C
It can be seen that about 300 kg of PO) and kin oil (KPO) can be taken. In the palm oil squeezing process, first, the oil palm bunches are steamed with steam to make it easier to extract the fruits and then removed. Thereafter, as shown in the figure, the fruit is squeezed to take out the oil, and at this time, about 1.5 times the amount of the squeezed liquid is discharged (281.7 kg of oil and 441.9 kg of water-
Total amount of water in the waste liquid discharged from each process). Therefore, if the annual production of palm oil is 8 million tons,
It is estimated that about 12 million tons of waste liquid are discharged annually. Moreover, the COD of this waste liquid is more than 20,000 ppm,
Efficient and economical treatment is difficult with conventional waste liquid treatment methods.
For example, there are 300 factories in Malaysia, where palm oil is mainly produced, and each factory discharges 40,000 tons of waste liquid annually. At present, wastewater is treated by a treatment pond called a lagoon, which is several hundred meters to as long as 1 km. Here, organic matter is converted to methane by natural methane fermentation.

[0005]

However, in such a method that relies on natural methane fermentation, oil palm (oil palm) waste liquid is a high-concentration waste liquid containing oil (COD200).
(00 ppm), it requires a residence time of one to two months to reduce the COD to 100 ppm, and methane gas, one of the greenhouse gases, is released into the atmosphere without any treatment or use. Since this method largely depends on natural conditions, it is often discharged into rivers without being able to meet the standard value due to unstable processing capacity. In addition, there was also a problem that there were many complaints from the surrounding residential areas because of off-flavors. Therefore, a new and economical waste liquid treatment method has been demanded. Further, since the wastewater containing a large amount of vegetable oil and kitchen wastewater discharged from the food service industry and fried food production factories and kitchen wastewater are not sufficiently treated by ordinary activated sludge treatment, wastewater capable of sufficiently treating these wastewater and wastewater A processing method was required.

The present invention has been made in view of such conventional problems, and it is an object of the present invention to efficiently treat organic components of palm oil waste liquid and to produce useful substances from the treated product. I do. That is, the present invention does not provide any advantage even if the vegetable oil waste liquid containing such a high concentration of organic substances is simply treated and released as CO ₂ or CH ₄ , so that the treatment is easy. An object is to produce a useful substance.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, when the reaction was not proceeded to methane fermentation in the first anaerobic treatment and the reaction was stopped by the production of organic acid, The time required for the anaerobic treatment process can be reduced to 10% or less compared to the time required for methane fermentation, and the biodegradability can be efficiently achieved by fully utilizing the ability of hydrogen bacteria (PHA-producing bacteria) using the organic acids obtained therefrom as raw materials. The present inventors have found that it is possible to produce plastic PHA and also to prevent the emission of methane gas, which is one of the causes of global warming, into the atmosphere. Based on this finding, they have found that the above problems can be solved, and have completed the present invention. Was.

That is, the present invention has the following configuration. (1) Vegetable oil waste liquid is subjected to anaerobic treatment, organic matter in the vegetable oil waste liquid is converted into organic acids by acid fermentation, and then sludge is separated and removed from the anaerobic treatment liquid by solid-liquid separation means, and the organic acid liquid from which solids are removed is removed. A method for producing biodegradable plastics from vegetable oil waste liquid, comprising concentrating and producing polyhydroxyalkanoate from the concentrated organic acid liquid by hydrogen bacteria. (2) The method for producing a biodegradable plastic according to the above (1), wherein the solid-liquid separation means is a centrifugal separation method. (3) The method for producing a biodegradable plastic according to (1), wherein the concentration is performed by heating. (4) The method for producing a biodegradable plastic according to (1), wherein the concentration is performed using an ion exchange resin. (5) The method for producing a biodegradable plastic according to (1), wherein the pH in the acid fermentation is adjusted by adding calcium carbonate.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the types of vegetable oil contained in the vegetable oil waste liquid to be treated include all those which are liquid at room temperature and obtained from plant seeds, such as oil palm (oil palm). Palm oil from pulp, palm kernel oil from seed, soybean oil, sesame oil, camellia oil, rapeseed oil, olive oil, and the like, which are used in foods, soaps, and paints.

FIG. 1 shows a block diagram of each step of the method for producing a biodegradable plastic from waste vegetable oil of the present invention.
Hereinafter, each step will be sequentially described. The anaerobic treatment of the present invention is performed under anaerobic conditions so that organic substances can be converted into organic acids by anaerobic bacteria. To stop. In general, methane fermentation converts organic matter into organic acids, mainly acetic acid, and then converts it to methane by methane bacteria.However, the time required to convert organic matter into organic acids is shorter than the time required for whole methane fermentation. Less than 10%. Therefore, the present invention is characterized in that the suspension is stopped at the stage when the organic matter in the vegetable oil waste liquid is converted into the organic acid.

In the present invention, it is necessary to separate the organic acid obtained therefrom from the waste liquid after the anaerobic treatment, and the separation is performed by a solid-liquid separation means. Examples of the solid-liquid separation means of the present invention include a method for separating sludge from an anaerobic treatment liquid by a centrifugal separation method, sedimentation separation by addition of alkali, gravity filtration, vacuum filtration, and filtration methods such as pressure filtration. .

As a method for concentrating an organic acid solution after sludge separation, there are a method of concentrating and separating an organic acid from a supernatant using an ion exchange resin, and a method of heating and concentrating a dilute organic acid solution to reduce the volume. . According to the ion exchange resin method, an electrolyte component containing an organic acid is taken out from a waste liquid and separated, and other components are removed, so that efficient fermentation can be performed on the organic acid component. The problem is that one operation is added. In the latter heat concentration method, the heat source of the heat concentration can be easily obtained, for example, by burning a bunch or a leaf of oil palm. The waste liquid containing the concentrated organic acid is directly used for PHA production by hydrogen bacteria. In this case, inexpensive calcium carbonate is used for pH adjustment in the first organic acid fermentation. Since calcium carbonate is hardly soluble, it can be dissolved if the pH is lowered only by adding it, and the pH can be kept almost at around neutral without a control device such as a pH sensor. Since calcium carbonate is contained in the sludge, the value of the recovered sludge as a fertilizer or soil conditioner also increases. Furthermore, if a method other than alkali addition such as centrifugation is used for the sedimentation and separation of sludge, the sludge can be returned to the anaerobic treatment tank for organic acid generation without damaging the sludge. The continuous anaerobic treatment accompanied by the recycling of sludge has the advantage that the residence time can be shortened and the volume of the apparatus can be reduced.

Arcaligenes is a hydrogen bacterium (PHA-producing bacterium) that produces PHA from a concentrated organic acid solution.
eutrophus. Usually, in a system for producing substances using microorganisms, it is necessary to prevent contamination by other microorganisms because a single microorganism is used. Therefore, sterilization equipment is required and it takes time. In this process, the composition of the effluent composition with a high concentration and low nitrogen content and the ability of PHA producing bacteria (usually the bacteria stop their activity and produce spores or die under anoxic condition even in the presence of a carbon source. , PH
Under the same conditions, the A-producing bacterium once accumulates a carbon source in the form of PHA, and degrades the accumulated PHA to produce a protein when the condition becomes nitrogen-rich again. ) Enables preferential culture in open systems. As a result, management becomes extremely easy, and plant construction costs and running costs can be reduced.

[0014]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1 This example describes a process in which an organic component of a palm oil waste liquid is converted into an organic acid, which is used as a raw material for a biodegradable plastic. First, palm oil waste liquid is subjected to anaerobic treatment, where organic components are converted into organic acids centered on acetic acid. Next, sludge is separated from the anaerobic treatment liquid, and the organic acid is concentrated and separated from the supernatant using an ion exchange resin.
Using this concentrated organic acid solution, hydrogen bacterium produces polyhydroalkanoate (PHA), which is a biodegradable plastic.

1) Production of Organic Acid by Anaerobic Treatment of Palm Oil Waste Liquid Palm oil waste liquid was passed through a reactor containing sludge collected from a palm oil treatment pond. Seal the reactor,
When sodium hydroxide was added to adjust the pH to 7, organic acids centering on acetic acid could be continuously produced. The residence time of the waste liquid at this time was 5 days. The experimental results are shown in FIG. As shown in FIG.
It can be seen that the organic acid was stably generated at a concentration of g / liter.

2) Separation of Suspended Solids from Organic Acid-Containing Waste Liquid As a method for removing suspended solids (SS) containing sludge from palm oil waste liquid in which an organic acid was generated, sedimentation separation by addition of an alkali was attempted. S at pH 10 and pH 11
When examining the particle size distribution of the S particles, it was found that a slight difference in pH greatly changes the particle size. As a result, sedimentation was facilitated and SS could be easily separated.

3) Separation of acetic acid and the like from palm oil waste liquid by ion exchange resin An attempt was made to separate organic acids from waste liquid from anaerobic treatment using anion exchange resin. In this case, it was found that SS in the processing solution strongly inhibited the adsorption of the organic acid. On the other hand, it was found that when the SS was removed by adding an alkali, the organic acid could be recovered from the treated waste liquid and concentrated and separated. Also,
It was found that the COD of the waste liquid after the organic acid separation was reduced to about 10% before the separation. In the ion exchange operation, when desorbing an organic acid which is usually adsorbed on an anion exchange resin, Na
It is common to desorb with a Cl solution, but then a large amount of alkali is required to desorb the chloride ions adsorbed during the desorption, so it was eluted with a high concentration sodium hydroxide solution. Is more advantageous. Examination of the adsorption volume (breakthrough volume) with respect to pH and chloride ion concentration revealed that chloride ion concentration had a large effect on adsorption.
In addition, it was found that, after acetic acid adsorption, elution with a high-concentration sodium hydroxide solution enabled sufficient concentration and separation of organic acids even with an alkaline solution. Therefore, in this ion exchange operation, the organic acid is separated as sodium organic acid.

4) Production of PHA Using Organic Acid Separated from Palm Oil Waste Liquid as Raw Material The organic acid separated from the treated waste liquid by an ion exchange resin is
Hydrogen bacteria (Arcaligenes eutrophu)
An attempt was made to accumulate PHA in the cells of s).
In this experiment, a semi-batch culture was used in which the separated organic acid was continuously supplied into the culture tank, but the cells were not discharged from the tank. The experimental results are shown in FIG. Summarizing the results in FIG. 3, the PHA productivity was 0.6 kg / (hm ³ ), the PHA yield per organic acid was 0.35 kg / kg, and the PHA content was 0.8 kg / kg.

5) Material Balance and Equipment Capacity The results of a trial calculation of the concentration and separation of acetic acid by an ion exchange resin in a standard palm oil factory in Malaysia will be described. The operation will be continued 365 days. And 81,000 tons of oil palm
Assuming that 15,000 t / year of water is processed using 15,000 t / year of water to produce 27,000 t / year of palm oil, a tank volume of approximately 700 m ³ is calculated. Furthermore,
The treatment liquid that has flowed out causes the precipitation and separation of SS by the addition of an alkali. Sodium hydroxide is required for anaerobic treatment and SS separation. On the other hand, the processing solution containing the organic acid excluding SS is
Separated by ion exchange resin. 9,500 tons of organic acid sodium (concentrated 800 tons in solid content, 500 tons in organic acid only) can be obtained annually to a concentration of about 8.4%. In the ion exchange operation, 50 kg of organic acid can be recovered per ton of adsorbent, so if the desorption operation is repeated every day, 500 [t / year] x 1000 [kg / t] / 50 [kg / m ³ ] / 365 [ Times /
Year] = 28 m ³ of ion exchange equipment is required.

Since organic components other than the separated organic acid still remain in the processing solution, they are removed with activated carbon. The activated carbon at this time shall be made from coconut shells. This activated carbon is used as it is as a soil conditioner without regeneration. On the other hand, the alkaline liquid from which organic components have been removed
The coconut shell is concentrated with the heat of combustion. At this time, the evaporated water is condensed to be treated water. From a zero emission point of view, it makes sense to use sodium hydroxide as a desorbent for organic acids in ion exchange. In this method, it is only necessary to replenish the amount removed as an organic acid sodium out of the system. On the other hand, if the generated organic acid sodium is used for on-site PHA generation, the net organic acid amount excluding the sodium content is 500 tons / year.
The HA yield is 0.35, which is 175 tons / year. Since the productivity of PHA is 0.6 kg / (hm ³ ), the culture tank volume for PHA production is 175 [t / year] × 1000 [kg / t] / (0.6 [kg / (hm ³ )] × 365
[Sun] become ^{× 24 [h] = 33m 3} .

Example 2 This example employs a means for reducing the volume by heat concentration instead of the means for separating and concentrating the organic acid produced in Example 1 by ion exchange chromatography. Inexpensive calcium carbonate is used for pH adjustment in organic acid fermentation. Calcium carbonate is hardly soluble, so it will dissolve if the pH drops just by adding it,
The pH can be kept almost neutral without a control device such as a pH sensor. Since calcium carbonate is contained in the sludge, the value of the recovered sludge as a fertilizer or soil conditioner also increases. In addition, surplus energy obtained by burning food waste generated from the oil pressing step is used for concentration of waste liquid. Thereby, the operation cost of the whole process can be reduced. The total energy required for the process can be provided by the combustion energy of about 20% of the coconut shell waste generated by the average mill.

1) Utilization of Calcium Carbonate for pH Adjustment in Organic Acid Production from Balm Oil Waste Liquid In this example, the palm oil waste liquid was passed from a palm oil treatment pond to a reactor containing sludge, but 1 liter daily. Per gram of calcium carbonate was added. As a result, the pH of the reaction solution was stabilized between 5.8 and 6.3. The retention time of the waste liquid was set to 5 days as in 1) of Example 1, but it was found that the organic acid was produced at a concentration of 10 g / liter as in the result shown in FIG. At this time, the selectivity of acetic acid per organic acid was about 70%, and the other main organic acid was propionic acid.

2) Production of PHA using organic acid obtained by heating and concentrating palm oil waste liquid as raw material The supernatant liquid obtained by separating sludge from waste liquid containing organic acid after anaerobic treatment of palm oil waste liquid is concentrated 30 times by evaporator. did. Thereby, the organic acid concentration in the waste liquid is 300 g /
Rose to liters. The COD of the condensed water is 60
ppm. After the concentrated organic acid waste liquid was sterilized by steam, a half-batch culture of hydrogen bacteria was performed. FIG. 4 shows the results. According to FIG. 4, since the concentrated solution of the anaerobic treatment solution of the palm oil waste liquid is directly used, it is considered that components other than the organic acid are also contained at a somewhat high concentration, but the growth of the bacterial cells was not inhibited. You can see that. Although the organic acid in the concentrated waste liquid is consumed, the concentration of the organic acid in the fermented liquor can be suppressed to a low level because the operation is performed in a half-batch operation, and finally the concentration can be reduced to 0 (FIG. 4B) reference). On the other hand, the concentration of hydrogen bacteria including PHA increased, and eventually exceeded 20 g / liter (see FIG. 4 (a)). Even if the fermentation time (treatment time) is limited to 3 days, the bacterial cell concentration is about 20 g / liter and PHA
The concentration reached 10 g / l and the PHA content reached 50%. Further, it can be seen that a slight amount of nitrogen (ammonia) remaining in the waste liquid has been completely removed.

Since this process is not only a PHA production process but also a wastewater treatment process, fermentation in an open system without steam sterilization is required. So 50%
The batch production of PHA was tested in a system without steam sterilization using an acetic acid solution. At this time, the acetic acid concentration in the fermentation broth was 1
A concentrated solution of acetic acid was added, taking care not to exceed g / l. Moreover, 0.1% pulse of fresh sludge obtained from the sewage treatment plant after 48 hours of cultivation was introduced so that the influence of the open system was remarkable. The result is shown in FIG. From the figure, it can be seen that acetic acid is consumed (see FIG. 5 (b)) and PHA is accumulated despite the open system and sludge added (FIG. 5 (a)).
reference). Also in this case, the PHA content in the cells reached 50% or more.

Even if the anaerobic treating solution of the concentrated palm oil waste liquid is directly used or PHA is produced in an open system without steam sterilization, the organic acid is consumed without any major obstacle and converted to PHA. It turned out to be. In this case, the concentration of the organic acid in the fermentation broth is zero, or
Very low level. In addition, nitrogen (ammonia) could be reduced to a level that could not be detected at all. However, the COD components other than the organic acids were not consumed. While 90% of the organic components of the anaerobic wastewater were occupied by organic acids, the remaining 10% of the organic components were not consumed in the fermentation of hydrogen bacteria.

3) Mass Balance and Equipment Capacity The following describes the results of a trial calculation of heat concentration of acetic acid with calcium carbonate in a standard palm oil plant in Malaysia. The number of operating days, the amount of raw oil palm, the amount of water used, and the amount of palm oil produced were all set to the same conditions as in Example 1. First, the residence time of the waste liquid was set to one day because the residence time can be reduced because the sludge is circulated. Therefore, the size of the anaerobic treatment tank was set to 160 m ³ with a margin of 1/5 of 700 m ³ of Example 1. Regarding SS separation, SS
Was concentrated to a considerably high concentration. The SS containing the discharged calcium carbonate is supplied as a soil conditioner or a fertilizer. The processing solution containing the organic acid is concentrated 50-fold with a heat concentration device. Water vapor condensed at this time becomes treated water. Alternatively, if the steam at this time is used for steam sterilization of oil palm, steam distillation of oils and fats, etc., water can be largely saved. Thereafter, the waste liquid containing the concentrated organic acid is treated by semi-batch culture of hydrogen bacteria. The heat source required for heat evaporation is obtained from solid waste. For this, one-fifth of the total amount of solids discharged is required. At this time, since the nitrogen content of the waste liquid is considerably low, the microorganism must survive unless it is a microorganism such as a hydrogen bacterium that can accumulate carbon as PHA. Assuming that the waste liquid treatment time is 3 days, 1
22 operations are required. If three culture tanks are used, the processing amount is 1000 t / year, so 1000 /
122/3 = 2.7 t / time.

This high-concentration waste liquid flows in one operation. From the experience of the laboratory, since about 10 times the basic medium (liquid after solid-liquid separation is sufficient only for the purpose of dilution) is required at the initial stage, one fermentation tank has a capacity of about 30 times.
m ^{3 is} required. Further, since the same tank is used for inoculum fermentation, another same tank is required. This process purifies 30000 t / year (COD 20000 ppm) of wastewater from a standard oil mill to 39000 t
At the same time as obtaining t / y treated water (COD 60 ppm),
0.8 kg / kg of sludge containing PHA at a high concentration can be produced. (It is a wastewater treatment plant and a PHA production plant.) A major feature of the second embodiment is that the required consumables are only calcium carbonate and ammonium sulfate. It is small. Also, the fact that the process is simple seems to be an advantage over the first embodiment. On the other hand, it is considered that the difficulty is that considerable skill and careful operation are required in order to stably continue the open PHA fermentation.

Therefore, the method of Example 1 for concentrating and separating an organic acid with an ion-exchange resin is a method of reducing the amount of wastewater from a Japanese-style restaurant or a Chinese restaurant that uses a lot of vegetable oil such as tempura, a catering center or a small food processing plant. It seems to be suitable for the treatment of relatively little so-called kitchen wastewater. On the other hand, the volume reduction method using the combination of heat concentration and calcium carbonate of Example 2 seems to be suitable for the treatment of so-called production equipment wastewater, which has a very large amount of wastewater, such as a vegetable oil production plant or a large-scale processed food production plant. It is.

[0030]

As described in detail above, according to the method for producing a biodegradable plastic from a vegetable oil waste liquid of the present invention,
Not only can high-concentration wastewater containing oil be treated in a relatively short time without generating methane gas, which is one of the warming gases, as well as efficiently converting organic components in the wastewater to organic acids, From this, PHA, which is a biodegradable plastic, can be produced using microorganisms such as hydrogen bacteria. In addition, this PHA can be mixed with general-purpose plastics such as polyethylene and used for, for example, packaging materials and agricultural films. As a result, it is possible to exhibit an extremely excellent effect that general-purpose plastics, which have been difficult to decompose in the natural world and have been problematic in terms of environmental protection, can be converted into biodegradable products of environmental protection. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing steps of a method for producing a biodegradable plastic from waste vegetable oil of the present invention.

FIG. 2 is a graph showing organic oxidation by anaerobic treatment of palm oil waste liquid.

FIG. 3 is a graph showing the production of PHA from organic acids derived from palm oil waste liquid.

FIG. 4 is a graph showing the production of PHA from heat-concentrated organic acids derived from palm oil waste liquid, wherein (a) shows the concentration of bacterial cells,
It is a graph which shows the relationship between PHA density | concentration, organic acid consumption, and processing time, and (b) is a graph which shows the relationship between acetic acid density | concentration, other organic acid density | concentrations, nitrogen density, and processing time.

FIG. 5 is a graph showing the production of PHA from an organic acid in an open system, and is a graph showing the same relationship as (a) and (b) in FIG. 4;

FIG. 6 is a block diagram showing a step of extracting palm oil.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) // (C12P 7/62 C12R 1:05) (72) Inventor Yoshito Shirai Sensuicho, Tobata-ku, Kitakyushu-shi, Fukuoka No. 1-1 F-term in Kyushu Institute of Technology (Reference) 4B064 AD83 CA02 CB30 CC01 CC07 CD07 CD24 CE20 DA16 4B065 AA12X AC16 BB02 BB10 BC01 BC02 BD14 BD15 BD50 CA12 CA54 CA60 4D040 AA01 AA62 DD03 DD11 4J029 AB05 AC02 AD10

Claims (5)

[Claims] 1. An organic acid obtained by subjecting a vegetable oil waste liquid to anaerobic treatment, converting organic matter in the vegetable oil waste liquid into an organic acid by acid fermentation, and then separating and removing sludge from the anaerobic treated liquid by solid-liquid separation means to remove solid matter. A method for producing a biodegradable plastic from waste vegetable oil, comprising concentrating the liquid and producing polyhydroxyalkanoate from the concentrated organic acid liquid by hydrogen bacteria. 2. The method for producing a biodegradable plastic according to claim 1, wherein said solid-liquid separation means is a centrifugal separation method. 3. The method according to claim 1, wherein the concentration is performed by heating.
A method for producing the biodegradable plastic according to the above. 4. The method for producing a biodegradable plastic according to claim 1, wherein the concentration is performed by using an ion exchange resin. 5. The method for producing a biodegradable plastic according to claim 1, wherein the pH adjustment in the acid fermentation is performed by adding calcium carbonate.