TWI796066B - Method of treating paper container waste and method of producing polyhydroxyalkanoates using hydrolysate of paper container waste - Google Patents

Abstract

The present invention provides a method of treating paper container waste and a method of producing polyhydroxyalkanoates using hydrolysate of paper container waste. The method of treating paper container waste comprises (a) crushing the paper container waste into paper scraps and mixing the paper scraps with water to make paper scraps/water mixture; (b) treating the paper scraps/water mixture with heat and pressure to make scraps/pulp mixture; (c) adding hydrolase to the scraps/pulp mixture to produce the hydrolysate of paper container waste; and (d) obtaining the hydrolysate of paper container waste from the scraps/pulp mixture. The method of producing polyhydroxyalkanoates comprises providing the above hydrolysate of paper container waste and adding INER-Y5 strain and nitrogen source into the hydrolysate of paper container waste to produce polyhydroxyalkanoates. By the above methods of treating paper container waste and producing polyhydroxyalkanoates, a novel way of reducing paper container waste is provided.

Description

Waste paper container treatment method and method for producing polyhydroxyalkanoate using waste paper container hydrolyzate

The present invention relates to a waste paper container treatment method and a method for producing polyhydroxyalkanoate by using the waste paper container hydrolyzate, especially a waste paper container treatment method for decomposing the waste paper container into fermentable sugar and using the waste paper container for hydrolysis Process for the liquid production of polyhydroxyalkanoates.

The food/beverage packaging materials used in the food processing industry or catering industry generally choose paper containers composed of paper and plastic film. The production method of this type of paper container is to first provide paper/ Plastic composite material, then paper/plastic composite material is processed into the required container shape. Common paper containers on the market include bento lunch boxes, paper bowls or hand-cranked drink cups. Since the amount of paper containers used in the food processing industry or catering industry is very large, how to recycle waste paper containers is also an important environmental issue.

The recycling method of paper container materials is different from the general paper recycling method. The paper container materials also contain plastic film, so that the paper container materials must be pulped during the recycling process (that is, the paper containers are beaten into pulp, It takes a long time for subsequent processing to make recycled paper), so the recycled waste paper containers are usually not sent to ordinary waste paper recycling plants for processing, but to professional paper processing plants Slurry treatment of waste paper containers.

However, there are still problems in the recycling of waste paper containers. As mentioned above, due to the long time required for the waste paper container to be pulped, the length of pulp fibers formed after the waste paper container is processed into pulp is shorter than that of ordinary paper pulp. The fiber length of pulp formed by paper is much shorter, and the structural strength of paper made from short pulp is often weaker. Therefore, the pulp made from waste paper containers can only be made into low-value low-grade paper products. Because the value of low-grade paper products recycled from waste paper containers is low, most of the waste paper containers will not be purchased and reused by recycling plants, but will be sent to incinerators as general garbage for incineration. Burning plastic materials in waste paper containers will produce dioxins, causing another kind of environmental pollution. Based on the above reasons, it is still an unresolved problem to find other recycling methods for waste paper containers, so that the processed products of waste paper containers can have higher value and wider application, so as to further improve the recovery rate of waste paper containers.

The purpose of the present invention is to address the above problems, to provide a waste paper container treatment method, which includes the following steps: (a) crush the waste paper container into slag, and mix the slag with water to form a slag/water mixture, the The weight ratio of slag to water is 1:5~1:20; (b) the slag/water mixture is heated at a temperature of 100-150°C and pressurized at a pressure of 0.8~1.2 kg per square centimeter treatment to make the residue/water mixture into a residue/pulp mixture; (c) adding hydrolytic enzymes to the residue/pulp mixture to produce waste paper container hydrolyzate, wherein the hydrolytic enzyme converts the residue/pulp decomposing the cellulose in the mixture into sugars; and (d) removing the waste paper container hydrolyzate from the hydrolyzed residue/pulp mixture.

As mentioned above, in step a, the weight ratio of the slag to water is 1:10.

In the above method, in step b, the heat treatment of the slag/water mixture is steam heat treatment.

As mentioned above, in step b, the slag/water mixture is subjected to hot steam at a temperature of 120-150° C. and a pressure of 1 kg per square centimeter for 50 minutes.

As mentioned above, after step b is completed, the pH value of the residue/pulp mixture is adjusted to pH 4-6.

In order to achieve the above purpose and other purposes, the present invention provides a method for producing polyhydroxyalkanoate, which comprises the following steps: (a) providing the waste paper container hydrolyzate produced by the above waste paper container treatment method: and (b) converting The INER-Y5 strain and nitrogen source are added to the waste paper container hydrolyzate, so that the INER-Y5 strain can be fermented to produce polyhydroxyalkanoate.

Through the method for treating waste paper containers and the method for producing polyhydroxyalkanoate by using the hydrolyzate of waste paper containers as described above, a novel way of recycling waste paper containers is provided, thereby further improving the recycling rate of waste paper containers.

In order to fully understand the purpose, features and effects of the present invention, the present invention will be described in detail through the following specific embodiments and accompanying drawings, as follows:

The waste paper container processing method of the present embodiment is summarized as follows. First, the waste paper container is crushed into slag, and the slag is mixed with water to form a slag/water mixture, and the weight ratio of the slag to water is 1:5~1:20. Next, the slag/water mixture is heated and pressurized at a temperature of 100-150° C. and a pressure of 0.8-1.2 kg per square centimeter, so that the slag/water mixture is made into a slag/pulp mixture. Then, hydrolytic enzymes are added to the residue/pulp mixture to produce a waste paper container hydrolyzate, wherein the hydrolytic enzyme decomposes cellulose in the residue/pulp mixture into sugars. Finally, the waste paper container hydrolyzate is removed from the hydrolyzed residue/pulp mixture

It can be seen from the above process that the waste paper container treatment method of this embodiment is to decompose the cellulose in the waste paper container into sugar, rather than beating the waste paper container into pulp as in the conventional waste paper container treatment method. After the cellulose in the container is decomposed into sugar, the sugar in it can be fermented by microorganisms to produce high-value bioplastics or biofuels, making the processed products of waste paper containers more valuable and more widely used. application, thereby further improving the recycling rate of waste paper containers.

The specific process of the waste paper container treatment method in this embodiment is as follows.

First, wash and dry the collected waste paper container (weight about 200 grams), and then crush the above waste paper container (the paper and plastic film in it are crushed together), the crushing degree can reach more than 50 mesh, After the waste paper container is crushed, add water and mix it to form a slag/water mixture. The weight ratio of the slag to water after the waste paper container is crushed is 1:10 (can be adjusted within the range of 1:5~1:20, in other In the embodiment, the weight ratio of slag material to water can also be adjusted arbitrarily according to the requirements of the process). Then, use steam at 121°C (the heating temperature can be adjusted within the range of 100-150°C according to requirements) (the method of steam cooking and heating can make the heating of the slag/water mixture more uniform, but in other embodiments, Different heating methods can be selected according to the needs) and a pressure of 1.06 kg per square centimeter (the pressure can be adjusted within the range of 0.8-1.2 kg per square centimeter according to the needs) to cook, heat and pressurize the slag/water mixture for 50 Minutes, the fiber structure of the paper is sufficiently destroyed to make the residue/water mixture into a residue/pulp mixture.

After the slag/pulp mixture is prepared, the aforementioned slag/pulp mixture is left to cool down to 50°C, and the pH of the aforementioned slag/pulp mixture is adjusted to 5.0 with a dilute sulfuric acid solution with a concentration of 1 M (this pH The adjustment of the value is to facilitate the subsequent reaction of the hydrolytic enzyme added therein, that is, the pH environment suitable for the reaction of the hydrolytic enzyme is pH 5, and it can also be adjusted within the range of pH 4-6, and in other embodiments, it can still be used depending on the Different types of hydrolytic enzymes to adjust the pH value of the slag/pulp mixture), 30 FPU (also choose the concentration of 10-50 FPU, or adjust the concentration arbitrarily according to the needs) hydrolytic enzyme (in this embodiment, the fiber of Trichoderma is used) Sulfase is used as a hydrolytic enzyme, but other hydrolytic enzymes known to decompose cellulose can also be used, such as Novozymes Cellic® CTec3) added to the residue/pulp mixture for 96 hours of decomposition (depending on the need to decompose cellulose into sugar The sufficiency of quality or other processing conditions of the residue/pulp mixture to adjust the action time of the hydrolytic enzyme), which decomposes the cellulose in the residue/pulp mixture into sugar.

After the slag/pulp mixture is decomposed by hydrolytic enzymes for 96 hours, it is centrifuged (the centrifugal speed is 8000 rpm, which can be adjusted to 4000-12000 rpm in other embodiments) (in other embodiments, it can also be used Other separation and filtration methods to separate the components in the hydrolyzed slag/pulp mixture, such as fractional filtration) divide the hydrolyzed slag/pulp mixture into waste paper container hydrolyzate, plastic slag and paper slag, and the plastic slag floats in the waste On the liquid surface of the paper container hydrolyzate, the paper residue settles at the bottom of the waste paper container hydrolyzate. By separating the waste paper container hydrolyzate, plastic residue and paper residue into layers, the waste paper can be separated by using a filter screen or other tools Container hydrolyzate, plastic residue and paper residue, and use them for different purposes. The plastic slag is the slag formed from the plastic film in the waste paper container after the aforementioned treatment, and the plastic slag can be recycled into other plastic products. The main component of paper residue is lignin, which can be used as fuel or compost. The waste paper container hydrolyzate can be used as a material source for bacteria to produce bioplastic polyhydroxyalkanoates (Polyhydroxyalkanoates, PHA). The process of using waste paper container hydrolyzate for bacteria to produce PHA will be described in detail later.

The bioplastic production type exemplified in this embodiment is PHA, but in other embodiments, the waste paper container hydrolyzate containing sugar can be applied to produce other bioplastics (such as succinic acid, lactic acid, etc.), Biomass fuel may be used for other purposes, not limited to this embodiment.

Comparison test of different process conditions for waste paper container treatment methods

In order to compare the hydrolysis efficiency of the waste paper container treatment method of this embodiment with other different process conditions for hydrolyzing the cellulose in the waste paper container into sugars (including glucose and xylose), the following tests were carried out.

First, prepare four waste paper containers with the same weight and material. The above four waste paper containers are respectively set as the control group and the experimental group 1 to 3. Each group contains 50 grams of waste paper containers, and the water used in the subsequent It is 450 grams, that is, the solid-to-liquid ratio is 10%. Wherein the waste paper container of experimental group 2 is treated with the waste paper container treatment method of the above-mentioned present embodiment to obtain the waste paper container hydrolyzate; the waste paper container of experimental group 1 is treated with reference to the waste paper container of the above-mentioned present embodiment The method adjusts the heating time for treatment. The difference between the conditions and the experimental group 2 is that the cooking and heating time of the experimental group 2 is shortened to 25 minutes; the waste paper container of the experimental group 3 is adjusted and heated according to the waste paper container treatment method of the above-mentioned embodiment. Time is processed, and its condition difference with experimental group 2 is that the cooking and heating time of experimental group 3 is extended to 120 minutes; The difference between it and the experimental group 2 is that the control group does not undergo cooking and heating treatment.

After the waste paper container hydrolyzate was prepared from the waste paper container in the control group and the experimental group 1 to the experimental group 3, the waste paper container hydrolyzate in each group was detected by HPLC and UV equipment (the detection instrument was Agilent technologies 1200 series). The unit content of glucose and xylose obtained through hydrolytic enzyme decomposition, HPLC and UV detection procedures are carried out according to the instrument operation manual.

The contents of glucose and xylose units in the control group and the experimental groups 1 to 3 are shown in Table 1 below.

Table 1 - Glycose unit content of control group and experimental group 1 to experimental group 3 Glucose concentration (g/L) Xylose concentration (g/L) control group 41.17 9.93 Experimental group 1 53.74 17.19 Experimental group 2 57.6 17.75 Experimental group 3 47.96 15.54

In order to determine the maximum unit content of sugar (including glucose and xylose) that can be decomposed in the waste paper container, to calculate the sugar hydrolysis efficiency of the process of the control group and the process of the experimental group 1 to the experimental group 3, by dividing the control group Divide the sugar unit content in the waste paper container hydrolyzate obtained from experimental group 1 to experimental group 3 (how much glucose and xylose are decomposed per kilogram of waste paper container) by the maximum sugar that can be decomposed in the waste paper container The mass unit content (the maximum amount of glucose and xylose that can be decomposed per kilogram of waste paper container), the hydrolysis efficiency of the control group process and the experimental group 1 to experimental group 3 processes can be calculated.

The determination process of the maximum sugar unit content that can be decomposed in the waste paper container is as follows.

First, wash and dry the collected waste paper containers according to the above-mentioned waste paper container treatment conditions, and then crush the above waste paper containers (the paper and plastic film in them are all crushed together), and then the crushed waste paper Add 10 mL of 72% sulfuric acid to the container, mix well and shake for 2 hours, so that the waste paper container can fully react with the 72% sulfuric acid. The mixture was diluted 10 times and put into a sterilizing kettle to react at 121°C for 1 hour, so as to carry out heating and acid hydrolysis treatment, so as to fully decompose the cellulose in the waste paper container into sugar. After the above-mentioned heating and acidolysis procedure is completed, the temperature is lowered to room temperature, and solid-liquid separation is carried out with ash-free filter paper (ash content <0.01%), and the separated filtrate is subjected to HPLC and UV respectively (the detection instrument is Agilent technologies 1200 series) to detect the glucose and xylose content in the filtrate, and the HPLC and UV detection procedures were carried out according to the instrument operation manual. The above determination process was repeated three times to obtain the average value of the maximum sugar unit content. The maximum glucose unit content (theoretical glucose unit content) that can be decomposed per kilogram of waste paper container is 75.31g/L, and the maximum xylose unit content (theoretical xylose unit content) is 20.41 g/L.

Divide the unit content of sugar (including glucose and xylose) obtained in the control group and experimental groups 1 to 3 by the maximum unit content of sugar (including glucose and xylose) that can be decomposed in the waste paper container to calculate The hydrolysis efficiency of the process of the control group and the process of the experimental group 1 to the experimental group 3 is shown. The results are shown in Figure 1, through the waste paper container treatment method of this embodiment, the hydrolysis efficiency (the ratio of converting cellulose into sugar) of the control group is about 53%; the hydrolysis efficiency of the experimental group 1 is about It was 74%; the hydrolysis efficiency of experimental group 2 was about 79%; the hydrolysis efficiency of experimental group 3 was about 55%.

The production method of polyhydroxyalkanoate in this example is summarized as follows. Firstly, the waste paper container hydrolyzate obtained by the aforementioned waste paper container treatment method is provided. Next, the PHA-producing strain INER-Y5 and a nitrogen source were added to the waste paper container hydrolyzate, so that the INER-Y5 strain could use the carbon source (glucose) and nitrogen source in the waste paper container hydrolyzate to ferment and produce polyhydroxyalkanes esters. The specific process of the polyhydroxyalkanoate production method in this embodiment is as follows.

First, prepare 2 L of waste paper container hydrolyzate obtained by the aforementioned waste paper container treatment method. Next, prepare INER-Y5 strains (INER-Y5 strains are a type of bacilli, and you can also use yeasts that produce alcohol, lactic acid bacteria that produce lactic acid, or strains that are used to produce succinic acid). INER-Y5 strains are derived from Obtained by the Institute of Nuclear Energy of the Atomic Energy Commission of the Republic of China. The INER-Y5 strain was inoculated at a 10% inoculation ratio in the Nutrient Broth medium containing 40 g/L glucose and cultured at 30°C. It was measured by a spectrophotometer When the OD ₆₀₀ value of the bacterial solution concentration was close to 2, the bacterial solution was taken out and inoculated in the aforementioned waste paper container hydrolyzate with a 10% inoculation ratio, and the yeast extract of 0.9375 g/L was also added in the aforementioned waste paper container hydrolyzate ( yeast extract) and 1.5625 g/L soybean protein peptone (peptone) as a nitrogen source (the aforementioned nitrogen sources can be replaced by ammonium nitrate, ammonium sulfate, ammonium chloride, potassium nitrate, urea or other known nitrogen sources) to facilitate INER- Y5 strain grows, and the weight ratio of carbon source and nitrogen source in the waste paper container hydrolyzate (hereinafter referred to as the carbon-nitrogen ratio) is adjusted to 20:1 (in other embodiments, the carbon-nitrogen ratio can be between 5:1 and 200:1. Adjust within the range, or adjust the carbon-nitrogen ratio arbitrarily according to the composition of the medium or other requirements). The INER-Y5 strain was fermented and cultured in the waste paper container hydrolyzate adjusted to a specific carbon-to-nitrogen ratio for 48 hours at 37°C. During the fermentation process, the INER-Y5 strain would convert the sugar in the waste paper container hydrolyzate It is PHA. At this time, PHA exists in the INER-Y5 strain. After the fermentation is completed, put 50 mL of the fermentation broth into a centrifuge tube and centrifuge at 4000 rpm for 15 minutes to make the INER-Y5 bacteria settle at the bottom of the centrifuge tube. , and then take out the bacterial precipitate from the bottom of the centrifuge tube, dissolve the bacterial precipitate in chloroform to destroy the bacteria, and dissolve the PHA in the bacterial cell in chloroform, thereby obtaining PHA.

In this embodiment, the bacterium is destructed through chloroform, but in other embodiments, high pressure bacteriostasis, shock bacteriostasis, ultrasonic bacteriostasis, osmotic pressure bacteriostasis, and chemical solvent bacteriostasis can also be used Or freeze-thaw method, but not limited to the present embodiment.

In this embodiment, PHA is extracted through chloroform, but in other embodiments, the method of extracting PHA can also be selected from organic solvent extraction, physical mechanical extraction or supercritical extraction. In organic solvent extraction, organic The extraction solvent of the solvent extraction method may also be alcohol, hexane, n-heptane or other suitable solvents, and is not limited to this embodiment.

Production comparison test of PHA produced from different sources

First, prepare 1 L of waste paper container hydrolyzate and 1 L of glucose solution (concentration: 50 g/L), respectively add yeast extract and concentration of 3.75 g/L to the waste paper container hydrolyzate and glucose solution 6.25 g/L soybean protein, 3.7 g/L potassium dihydrogen phosphate (phosphorus element required for bacterial growth and replication, not an essential component for strain fermentation), 5.8 g/L dipotassium hydrogen phosphate (Phosphorus needed for bacterial growth and replication is not an essential component of strain fermentation), magnesium sulfate heptahydrate at a concentration of 0.02 g/L (magnesium needed for bacterial growth and replication is not an essential component of strain fermentation) and 0.1% trace elements (iron and copper in the trace elements are mainly used as catalysts in the enzyme system, and it is not an essential component for bacterial strain fermentation. In the present embodiment, the formula of trace elements is 2.78 grams of FeSO ₄ .7H ₂ O , 1.98 grams of MnCl ₂ .H ₂ O, 2.81 grams of CoSO ₄ .7H ₂ O, 1.67 grams of CaCl ₂ .2 H ₂ O, 0.17 grams of CuCl ₂ .2 H ₂ O, 0.29 grams of ZnSO ₄ .7 All H ₂ O is dissolved in 1L of 1M HCl, when adding the liquid medium, the formula of the above trace elements is diluted 1000 times before use). The waste paper container hydrolyzate added with the above components was used as the culture solution of the experimental group, and the glucose solution added with the above components was used as the culture solution of the control group. The additional components added to the above-mentioned waste paper container hydrolyzate and glucose solution are only components to further increase the yield of PHA, and are not essential components for the INER-Y5 strain to produce PHA, and the concentrations of the above components can be adjusted arbitrarily depending on the process conditions. For example, the medium used may contain 1-5 g/L of yeast extract, 2-8 g/L of protein, 2-5 g/L of potassium dihydrogen phosphate, 4-7 g/L of dipotassium hydrogen phosphate , 0.01~0.05 g/L magnesium sulfate or magnesium salt and 0.01~0.5% trace elements.

Next, culture the INER-Y5 strain in the aforementioned strain culture method. When the concentration of the INER-Y5 bacterial solution reaches an OD ₆₀₀ value close to 2, take out the INER-Y5 bacterial solution and inoculate it in the culture medium of the experimental group and the control group at a ratio of 10%. In the culture medium of the experimental group, the initial OD ₆₀₀ value _of the culture medium _of the experimental group and the culture medium of the control group was measured with a spectrophotometer. After the initial OD ₆₀₀ values of the culture fluid of the experimental group inoculated with the INER-Y5 strain and the culture fluid of the control group were measured, they were placed in a 37°C environment for fermentation for 48 hours.

After the experimental group and the control group were fermented for 48 hours, the samples of the experimental group and the control group were respectively taken to measure the OD value of the bacterial liquid of the experimental group and the control group with a spectrophotometer, and then 50 According to the aforementioned centrifugation process (centrifugation conditions: centrifuge at 4000 rpm for 15 minutes) to obtain the precipitated bacteria of the experimental group and the control group, measure the dry weight of the aforementioned experimental group and the control group (converted into The dry weight of the bacteria in grams), and according to the above-mentioned extraction process of PHA, the PHA in the experimental group and the control group were dissolved in 15 mL of chloroform, and the PHA/chloroform solution of the experimental group and the control group were Add 5 mL of deionized water into the solution, then shake for 10 minutes. After the shaking is completed, centrifuge the PHA/chloroform/deionized aqueous solution of both the experimental group and the control group at a speed of 4000 rpm. After the centrifugation, take out the experimental group The organic phase liquid in the lower layer of the solution of the control group was dried and concentrated, then weighed after drying and concentrated, and the weight obtained by weighing was used as the PHA weight of the experimental group and the control group. After weighing, use a proton nuclear magnetic resonance spectrometer (Varian Mercury Plus, purchased from Agilent Corporation) and according to the product operation manual of the proton nuclear magnetic resonance spectrometer, carry out proton nuclear magnetic resonance (NMR) spectral analysis on the aforementioned organic phase liquid to determine The PHA species produced through the above steps.

The comparison test results of PHA production of INER-Y5 strain using glucose solution and waste paper container hydrolyzate as material sources are shown in Table 1 below. The OD ₆₀₀ value of the control group increased from 0.055 to 3.7 from the beginning of the culture to 48 hours after the culture; the OD ₆₀₀ value of the control group increased from 0.053 to 7.1 from the beginning of the culture to 48 hours after the culture. The dry weight per liter of the strains in the control group was 0.864 grams after being cultured for 48 hours, and the dry weight per liter of the strains in the experimental group was 1.86 grams after being cultivated for 48 hours. The PHA output of the control group was 0.188 g/L after 48 hours of culture, and the PHA output of the experimental group was 0.541 g/L after 48 hours of culture. The ratio of the dry weight of PHA to the total dry weight of the control group was 21.76%. The dry weight of PHA in the control group accounted for 29.09% of the total dry weight of the bacteria. The results showed that compared with the glucose solution as the material source, the INER-Y5 strain used the waste paper container hydrolyzate as the material source to grow better, and the dry weight of the bacteria was heavier, and the INER-Y5 strain used the waste paper container hydrolyzate as the source. The output of PHA as a material source and the proportion of dry weight of PHA are both higher. From the above test results, it can be seen that the hydrolyzate of waste paper containers can not only be used as a source of microorganisms to produce PHA, but also the yield of PHA using the hydrolyzate of waste paper containers as a source is higher than that of traditional glucose sources.

Table 1-INER-Y5 strain uses glucose solution and waste paper container hydrolyzate as the PHA output comparison test results of the material source OD ₆₀₀ value after 48 hours of culture Dry weight per liter (g) PHA output (g/L) PHA dry weight ratio (%) control group 3.7 0.864 0.188 21.76 test group 7.1 1.86 0.541 29.09

The PHA analysis results of the experimental group and the control group are shown in Figure 2. From the NMR spectrum, it can be seen that the microorganisms can produce PHA regardless of the glucose solution or the waste paper container hydrolyzate as the source, and the types of PHA produced are Poly-3-hydroxybutyrate (P3HB). However, in other embodiments, different types of PHA can be produced through the adjustment of the culture medium source and the selection of strains, such as 3-hydroxybutyric acid and 4-hydroxybutyric acid copolymer (P3HB4HB), 3-hydroxybutyric acid And 3-hydroxyhexanoic acid copolymer (PHBHHx) and medium long chain PHA (Medium chain length polyhydroxyalkanoate), but not limited to this embodiment.

As mentioned above, by the above-mentioned waste paper container processing method and the method of producing polyhydroxyalkanoate using the waste paper container hydrolyzate, a novel waste paper container recycling method is provided, thereby further improving the waste paper container Recovery rate. At the same time, in the process of the above waste paper container treatment method, the cellulose in the waste paper container is only decomposed by hydrothermal pressure and enzyme decomposition, and there is no need to decompose the cellulose in the waste paper container by adding an acid-base solution to the hydrothermal treatment, so that The above waste paper container treatment method can avoid the use of acid-base solutions that are likely to cause environmental pollution, so it is more environmentally friendly, and the above waste paper container treatment method can decompose about 79% of the cellulose in the waste paper container into sugar. In addition, when the microorganisms used the waste paper container hydrolyzate as the material source to produce PHA, the yield of PHA was higher than that obtained when the microorganisms used the traditional glucose material source to produce PHA.

The present invention has been disclosed above with preferred embodiments, but those skilled in the art should understand that the embodiments are only used to describe the present invention, and should not be construed as limiting the scope of the present invention. It should be noted that all changes and substitutions equivalent to the embodiment should be included in the scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the scope of the patent application.

none

Fig. 1 shows the comparison of hydrolysis efficiency under different pretreatment conditions of the waste paper container treatment method according to the embodiment of the present invention. FIG. 2 shows the nuclear magnetic resonance spectra of PHA produced by the polyhydroxyalkanoate production method of the embodiment of the present invention and the control method.

none

Claims (9)

A method for treating waste paper containers, comprising the following steps: (a) Crush the waste paper container into slag, and mix the slag with water to form a slag/water mixture, the weight ratio of the slag to water is 1:5~1:20; (b) Heat the slag/water mixture at a temperature of 100-150°C and pressurize it at a pressure of 0.8-1.2 kg per square centimeter to make the slag/water mixture into slag/pulp mixture; (c) adding a hydrolytic enzyme to the residue/pulp mixture to produce a waste paper container hydrolyzate, wherein the hydrolytic enzyme decomposes cellulose in the residue/pulp mixture into sugars; and (d) Remove the waste paper container hydrolyzate from the hydrolyzed residue/pulp mixture. The method according to claim 1, wherein, in step a, the weight ratio of the slag to water is 1:10. The method according to claim 1, wherein, in step b, the heat treatment of the slag/water mixture is steam heat treatment. The method as claimed in claim 1, wherein, in step b, the slag/water mixture is subjected to hot steam at a temperature of 120-150° C. and a pressure of 1 kg per square centimeter for 50 minutes. The method according to claim 1, wherein, after step b is completed, the pH value of the slag/pulp mixture is adjusted to pH 4-6. A method for producing polyhydroxyalkanoate, which is to produce polyhydroxyalkanoate from the waste paper container hydrolyzate produced by the waste paper container treatment method described in any one of claims 1 to 5, the polyhydroxyalkanoate The ester production method comprises adding INER-Y5 strain and nitrogen source into the waste paper container hydrolyzate, so that the INER-Y5 strain ferments to produce polyhydroxyalkanoate. The method as claimed in item 6, wherein, in step b, elements of phosphorus, magnesium, iron and copper are added to the waste paper container hydrolyzate. The method according to claim 6, wherein, in step b, the weight ratio of the carbon source to the nitrogen source in the waste paper container hydrolyzate is 5:1-200:1. The method according to claim 8, wherein, in step b, the weight ratio of carbon source and nitrogen source in the waste paper container hydrolyzate is 20:1.

Images