Method for producing hydrogen through microplastic depolymerization reinforced bioelectricity fermentation
By enhancing the bioelectrofermentation hydrogen production through microplastic depolymerization, the problem of co-treatment of microplastics and sludge has been solved, achieving efficient resource utilization and energy recovery, increasing hydrogen production, and reducing carbon emissions.
Patent Information
- Application Number
- CN202511271676.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-08
- Publication Date
- 2025-12-09
AI Technical Summary
Existing technologies are difficult to efficiently handle the co-treatment of microplastics and sludge. Microplastics are difficult to degrade and have a high concentration in sludge, which increases the complexity of sludge treatment. At the same time, traditional treatment methods are energy-intensive, inefficient, and may cause secondary pollution.
A method for enhancing hydrogen production through bioelectrofermentation by depolymerizing microplastics was adopted. This method involves pretreating sludge with sodium hydroxide solution and then performing anaerobic fermentation. Subsequently, the mixture is coupled with the aging liquid of microplastics in a microbial electrofermentation system to achieve simultaneous depolymerization and hydrogen production.
It increased hydrogen production, overcame the substrate limitations and energy conversion bottlenecks of traditional bio-hydrogen production, reduced carbon emissions, and realized the resource utilization and energy recovery of microplastics.
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Figure CN121087111A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of sewage treatment, and particularly relates to a method for strengthening hydrogen production by bio-electric fermentation of microplastic depolymerization. BACKGROUND
[0002] Microplastics (MPs) are widely present in oceans, soils, freshwater systems and even the atmosphere. Polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET) are common types of microplastics in the environment, mainly derived from the degradation of plastic products, detergent beads, tire wear and industrial emissions. Due to the difficulty of natural degradation, the long-term accumulation of microplastics poses a serious threat to the ecosystem and human health. The surface of microplastics is easy to adsorb persistent organic pollutants and heavy metals, which exacerbates pollution diffusion. At the same time, microplastics can enter the human body through the food chain and potentially affect the endocrine system and cell function. At present, the main methods for treating microplastics include physical filtration, chemical oxidation and biodegradation, but they have high energy consumption, low efficiency and may cause secondary pollution. Therefore, it is urgent to develop efficient and environmentally friendly microplastic resourceization technologies.
[0003] With the acceleration of urbanization, the amount of waste activated sludge (WAS) produced by sewage treatment plants is increasing year by year. The high water content, easy odor and the presence of heavy metals / pathogens in WAS pose a great pressure on environmental governance. Therefore, effective sludge treatment is very important for the resource utilization of sludge. At the same time, the detection concentration of microplastics (such as PE and PP) in sludge is as high as 1000-5000 particles / kg (dry weight), and their difficult degradation characteristics further complicate sludge treatment. Therefore, co-treatment of microplastics and sludge fermentation broth has become a problem to be solved. SUMMARY
[0004] The present application aims to overcome the difficulties in the prior art and provide a method for strengthening hydrogen production by bio-electric fermentation of microplastic depolymerization.
[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions: The present application provides a method for strengthening hydrogen production by bio-electric fermentation of microplastic depolymerization, comprising the following steps: (1) mixing a sludge sample and a sodium hydroxide solution, adjusting the pH, and then sequentially performing pretreatment and anaerobic fermentation to obtain a fermentation broth; (2) aging microplastics to obtain an aging liquid; (3) mixing the sludge sample and a buffer solution, sequentially performing preliminary operation and secondary operation to obtain a microbial electric fermentation system; (4) mixing the aging liquid and an aqueous solution of the fermentation broth, inoculating into the microbial electric fermentation system, and performing fermentation to produce hydrogen.
[0006] Preferably, the pH of the sludge sample in step (1) is 6.5-7.5, the TSS concentration is 10-25 g / L, and the VSS concentration is 9-15 g / L.
[0007] Preferably, the concentration of the sodium hydroxide solution in step (1) is 0.5-1.5 g / mL. The mass ratio of the sodium hydroxide solution to the TSS in the sludge sample is 0.08-0.1:1. The target value of the pH adjustment in step (1) is 10-12.
[0008] Preferably, the temperature of the water bath in the pretreatment in step (1) is 80-90°C, and the time is 50-70 min. The temperature of the shaker in the anaerobic fermentation in step (1) is 34-37°C, the rotation speed is 120-140 rpm, and the time is 3-5 days.
[0009] Preferably, the particle size of the microplastics in step (2) is 100-200 μm. The mass-to-volume ratio of the microplastics to water during the aging treatment in step (2) is 18-22 g:1 L. The temperature of the aging treatment in step (2) is 170-200°C, and the time is 3-6 h.
[0010] Preferably, the buffer solution in step (3) is a phosphate buffer solution, the concentration of the buffer solution is 80-120 nM, and the concentration of sodium acetate in the buffer solution is 1400-1600 mg / L. The volume ratio of the sludge sample to the buffer solution in step (3) is 1:8-10.
[0011] Preferably, the number of cycles of the preliminary operation in step (3) is ≥3, and the operation time of a single cycle is 6-8 days. The time of the secondary operation in step (3) is 5-8 days. The external voltage of the primary operation and the secondary operation in step (3) is 0.6-1 V.
[0012] Preferably, in the aqueous solution of the fermentation broth in step (4), the volume ratio of the fermentation broth to water is 1:1-2. The volume of the aging liquid is 1-17% of the volume of the aqueous solution of the fermentation broth.
[0013] Preferably, the volume of the aging liquid in step (4) is 5-15% of the volume of the sludge sample in step (3).
[0014] Preferably, the pH is adjusted during the mixing in step (4), and the target value of the pH adjustment is 6.5-7.5.
[0015] The application provides a method for hydrogen production by microplastic depolymerization and enhanced bio-electro-fermentation, wherein sludge samples and sodium hydroxide solution are mixed, and then pretreatment and anaerobic fermentation are sequentially performed to obtain fermentation liquor; microplastics are subjected to aging treatment to obtain aging liquor; the sludge and buffer solution are mixed, and then preliminary operation and secondary operation are sequentially performed to obtain a microbial electro-fermentation system; the aging liquor and the aqueous solution of the fermentation liquor are inoculated into the microbial electro-fermentation system, and then hydrogen production is performed after pH adjustment. In the application, hot alkali is used for pretreatment of the sludge, so that the cell walls of sludge flocs and microorganisms are damaged, the sludge lysis rate is improved, the anaerobic fermentation process is accelerated, the generation of short-chain fatty acids is promoted, and the purpose of maximizing resource and energy recovery is achieved. Meanwhile, the application first couples microplastic depolymerization with bio-electrochemical hydrogen production, and synchronously drives efficient hydrogen production on the cathode (hydrogen production is increased by 23.33%), thereby breaking through the substrate limitation and energy conversion bottleneck of traditional biological hydrogen production, and helping to reduce carbon emissions. BRIEF DESCRIPTION OF DRAWINGS
[0016] Figure 1 The figure is a graph of the relationship between hydrogen production and time during the operation of the example and comparative example 1. Figure 2 The figure is a graph of the relationship between protein concentration and time during the operation of the example and comparative example 1. DETAILED DESCRIPTION
[0017] A method for hydrogen production by microplastic depolymerization and enhanced bio-electro-fermentation, comprising the following steps: (1) mixing sludge samples and sodium hydroxide solution, adjusting pH, and then sequentially performing pretreatment and anaerobic fermentation to obtain fermentation liquor; (2) aging treatment of microplastics to obtain aging liquor; (3) mixing sludge samples and buffer solution, and then sequentially performing preliminary operation and secondary operation to obtain a microbial electro-fermentation system; (4) mixing the aging liquor and the aqueous solution of the fermentation liquor, inoculating into the microbial electro-fermentation system, and then performing hydrogen production by fermentation.
[0018] In the application, the sludge is subjected to natural sedimentation to obtain sludge samples.
[0019] In the application, the temperature of the natural sedimentation is preferably 1-6℃, further preferably 2-5℃, and more preferably 3-4℃; the time is preferably 20-28h, further preferably 22-26h, and more preferably 23-25h.
[0020] In the present application, the pH of the sludge sample in step (1) is preferably 6.5-7.5, further preferably 6.6-7.4, and more preferably 6.8-7.2; the TSS concentration is preferably 10-25 g / L, further preferably 15-20 g / L, and more preferably 16-18 g / L; and the VSS concentration is preferably 9-15 g / L, further preferably 10-14 g / L, and more preferably 12-13 g / L.
[0021] In the present application, the concentration of the sodium hydroxide solution in step (1) is preferably 0.5-1.5 g / mL, further preferably 0.6-1.4 g / mL, and more preferably 0.8-1.2 g / mL.
[0022] In the present application, the mass ratio of the sodium hydroxide solution to the TSS in the sludge sample is preferably 0.08-0.1:1, further preferably 0.085-0.095:1, and more preferably 0.088-0.092:1.
[0023] In the present application, after the sludge sample and the sodium hydroxide solution are thoroughly mixed, hydrochloric acid is used to adjust the pH.
[0024] In the present application, the concentration of the hydrochloric acid is preferably 1.5-2.5 M, further preferably 1.6-2.4 M, and more preferably 1.8-2.2 M.
[0025] In the present application, the target value of the pH adjustment in step (1) is preferably 10-12, further preferably 10.5-11.5, and more preferably 10.8-11.2.
[0026] In the present application, the temperature of the water bath for the pretreatment in step (1) is preferably 80-90℃, further preferably 82-88℃, and more preferably 84-86℃; and the time is preferably 50-70 min, further preferably 55-65 min, and more preferably 58-62 min.
[0027] In the present application, the anaerobic fermentation in step (1) is carried out in an anaerobic fermentation device, a fermentation bottle is used as the reactor, a sampling tube, an air pipe, and a gas bag are installed, the fermentation bottle is made of glass, and the fermentation bottle is placed in a shaking table to carry out the anaerobic fermentation acid production process. The entire reactor is in a sealed anaerobic environment during operation, and the fermentation is stopped after the production of short-chain fatty acids is stable.
[0028] In the present application, the temperature of the shaking table for the anaerobic fermentation in step (1) is preferably 34-37℃, further preferably 34.5-36.5℃, and more preferably 35-36℃; the rotation speed is preferably 120-140 rpm, further preferably 125-135 rpm, and more preferably 128-132 rpm; and the time is preferably 3-5 d, and more preferably 4 d.
[0029] In the present application, the microplastics in step (2) are one or more of polyethylene, polypropylene and polyethylene terephthalate.
[0030] In the present application, the particle size of the microplastics in step (2) is preferably 100-200 μm, further preferably 120-180 μm, and more preferably 140-160 μm.
[0031] In the present application, the mass-volume ratio of the microplastics to water during the aging treatment in step (2) is preferably 18-22 g:1 L, further preferably 19-21 g:1 L, and more preferably 19.5-20.5 g:1 L.
[0032] In the present application, the temperature of the aging treatment in step (2) is preferably 170-200℃, further preferably 180-190℃, and more preferably 184-186℃; and the time is preferably 3-6 h, further preferably 3.5-5.5 h, and more preferably 4-5 h.
[0033] In the present application, the buffer in step (3) is a phosphate buffer solution, and the concentration of the buffer is preferably 80-120 nM, further preferably 90-110 nM, and more preferably 95-100 nM; and the concentration of sodium acetate in the buffer is preferably 1400-1600 mg / L, further preferably 1450-1550 mg / L, and more preferably 1480-1520 mg / L.
[0034] In the present application, the volume ratio of the sludge sample to the buffer in step (3) is preferably 1:8-10, further preferably 1:8.5-9.5, and more preferably 1:8.8-9.2.
[0035] In the present application, the number of cycles of the preliminary operation in step (3) is preferably ≥3, further preferably ≥4, and more preferably ≥5; and the operation time of a single cycle is preferably 6-8 days, and more preferably 7 days.
[0036] In the present application, the preliminary operation starts from the second cycle, and before the start of each cycle, sludge is supplemented, and the volume ratio of the supplemented sludge to the buffer in step (3) is preferably 1:8-10, further preferably 1:8.5-9.5, and more preferably 1:8.8-9.2.
[0037] In the present application, after the preliminary operation is completed, the inoculation of sludge is stopped, and the concentration of sodium acetate is adjusted, and the target concentration of the adjustment is preferably 800-1000 mg / L, further preferably 850-950 mg / L, and more preferably 880-920 mg / L.
[0038] In the present application, the time of the secondary operation in step (3) is preferably 5-8 days, further preferably 5.5-7.5 days, and more preferably 6-7 days.
[0039] In the present application, the external voltage of the primary operation and the secondary operation in step (3) is preferably 0.6-1 V, further preferably 0.7-0.9 V, and more preferably 0.8-0.85 V.
[0040] In the present application, the volume ratio of the fermentation broth to water in the aqueous solution of the fermentation broth in step (4) is preferably 1:1-2, further preferably 1:1.2-1.8, and more preferably 1:1.4-1.6.
[0041] In the present application, the volume of the aging liquid is preferably 1-17% of the volume of the aqueous solution of the fermentation broth, further preferably 5-12%, and more preferably 8-9%.
[0042] In the present application, the volume of the aging liquid in step (4) is preferably 5-15% of the volume of the sludge sample in step (3), further preferably 6-14%, and more preferably 8-12%.
[0043] In the present application, the pH is adjusted during the mixing in step (4), and the reagent for adjusting the pH is hydrochloric acid. The concentration of the hydrochloric acid is preferably 1.5-2.5 M, further preferably 1.6-2.4 M, and more preferably 1.8-2.2 M. The target value of the adjusted pH is preferably 6.5-7.5, further preferably 6.6-7.4, and more preferably 6.8-7.2.
[0044] The technical solutions provided by the present application will be described in detail below in conjunction with the examples, but they should not be understood as limiting the scope of protection of the present application.
[0045] Example 1
[0046] The sludge was allowed to settle naturally at 4℃ for 24 h, and the supernatant was removed for concentration. Then, the impurities were removed by passing through a 40-mesh sieve to obtain a sludge sample, which had a pH of 6.97, a TSS of 17.65 g / L, and a VSS of 11.09 g / L. A beaker was used to take 3 L of the sludge sample, 4.7 g of sodium hydroxide solution (1 g / mL) was added dropwise while stirring with a glass rod, 2 M HCl was used to adjust the pH to 12, and then the sample was placed in a water bath for pretreatment, with the temperature set to 85℃ and the time set to 60 min. Then, the sample was cooled to room temperature for use.
[0047] Anaerobic fermentation device assembly: Fermentation bottle was used as reactor, sampling tube and air pipe (connected with 500 mL gas bag to store gas) were installed, fermentation bottle volume was 500 ml, fermentation bottle material was glass, fermentation bottle was placed in a shaking bed, shaking bed temperature was set to 35℃, rotation speed was set to 130 rpm, 4d anaerobic fermentation process was carried out, the whole reactor ran in a sealed anaerobic environment, fermentation was stopped after short-chain fatty acid production was stable, fermentation liquor was reserved for later use.
[0048] Microplastic pretreatment: polyethylene (PE) microplastic particles with a particle size of 150 μm were selected, hydrothermal reaction kettle was used for aging pretreatment, temperature was set to 170℃, time was 5 h, mass-volume ratio of microplastic and water was 20 g:1 L, aging liquid was obtained, and cooled to room temperature for later use.
[0049] Microbial electrofermentation system start-up; the reactor was connected with a voltage of 0.8 V, and a 10Ω resistor was connected to measure the current of the reactor. In the start-up stage, the sludge sample was inoculated with a sludge sample and buffer solution in a volume ratio of 1:9, the buffer solution was phosphate buffer solution (100 mM PBS), and the concentration of sodium acetate was 1500 mg / L. Three cycles were run for 7 days each cycle, and from the second cycle, the sludge was inoculated before each cycle according to the volume ratio of sludge sample to buffer solution of 1:9. After the preliminary operation, the inoculation of sludge was stopped, the concentration of sodium acetate was adjusted to 1000 mg / L, and the operation was continued for 7 days.
[0050] Add aging liquid and fermentation liquor: dilute the fermentation liquor and water in a ratio of 1:1 to obtain an aqueous solution of fermentation liquor, then mix the aqueous solution of fermentation liquor with the aging liquid in a ratio of 5% of the volume of the aqueous solution of fermentation liquor, and the volume of the aging liquid is 10% of the volume of the sludge sample in step (3); then adjust the pH to 7 with 2 mol / L HCl, and add it to the microbial electrofermentation system, connect the gas bag to collect the gas, and the whole process is in strict anaerobic environment.
[0051] Example 2
[0052] The difference between Example 2 and Example 1 is that in the last step, the volume of the aging liquid is 10% of the volume of the aqueous solution of fermentation liquor, and the rest of the process is the same.
[0053] Example 3
[0054] The difference between Example 3 and Example 1 is that in the last step, the volume of the aging liquid is 15% of the volume of the aqueous solution of fermentation liquor, and the rest of the process is the same.
[0055] Comparative Example 1
[0056] The difference between Comparative Example 1 and Example 1 is that in the last step, no aging liquid is added for fermentation.
[0057] The hydrogen production and time relationship in the examples and Comparative Example 1 are as follows: Figure 1 As shown, from Figure 1 It can be seen that the hydrogen production increased significantly after adding 5% PE microplastic aging liquid, reaching a peak of 35.92 mL on the second day, which was 23.33% higher than that without PE aging liquid. However, the hydrogen production decreased in the groups with high concentrations of 10% and 15% PE aging liquid, possibly due to the high concentrations causing some toxicity to microorganisms. This indicates that low concentrations of PE aging liquid can effectively promote the production of hydrogen from electrocatalytic sludge fermentation liquid.
[0058] The relationship between protein concentration and time in the examples and Comparative Example 1 is as follows: Figure 2 As shown, from Figure 2 It can be seen that the highest protein consumption (70.78 mg COD / L) was achieved on the second day in the low-concentration aging solution of 5%. In comparison, the protein consumption in Experiment 1 without PE aging solution (60.63 mg COD / L) showed a similar trend to that with PE aging solution, decreasing sharply on the first day and then gradually stabilizing.
[0059] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for enhancing hydrogen production by bio-electro-fermentation of microplastic depolymerization, characterized in that, The method comprises the following steps: (1) mixing a sludge sample and a sodium hydroxide solution, adjusting pH, and then sequentially performing pretreatment and anaerobic fermentation to obtain a fermentation liquor; (2) aging microplastics to obtain an aging liquor; (3) mixing the sludge sample and a buffer solution, sequentially performing primary operation and secondary operation, and obtaining a microbial electro-fermentation system; (4) mixing the aging liquor and an aqueous solution of the fermentation liquor, inoculating the microbial electro-fermentation system, and performing fermentation to produce hydrogen.
2. The method for enhancing hydrogen production through bioelectrofermentation by microplastic depolymerization as described in claim 1, characterized in that, In step (1), the pH of the sludge sample is 6.5-7.5, the TSS concentration is 10-25 g / L, and the VSS concentration is 9-15 g / L.
3. The method of claim 2, wherein the microplastic depolymerization is enhanced by the bioelectrofermentation. In step (1), the concentration of the sodium hydroxide solution is 0.5-1.5 g / mL. The mass ratio of the sodium hydroxide solution to TSS in the sludge sample is 0.08-0.1:
1. In step (1), the target value of the adjusted pH is 10-12.
4. The method of claim 3, wherein the microplastic depolymerization is enhanced by the bioelectrofermentation. In step (1), the water bath temperature of the pretreatment is 80-90℃, and the time is 50-70 min. In step (1), the shaking table temperature of the anaerobic fermentation is 34-37℃, the rotation speed is 120-140 rpm, and the time is 3-5 days.
5. The method of claim 4, wherein the microplastic depolymerization is enhanced by the bioelectrofermentation. In step (2), the particle size of the microplastics is 100-200 μm. In step (2), the mass-volume ratio of the microplastics to water during the aging treatment is 18-22 g:1 L. In step (2), the temperature of the aging treatment is 170-200℃, and the time is 3-6 h.
6. The method of claim 5, wherein the microplastic depolymerization is enhanced by the bioelectrofermentation. In step (3), the buffer solution is a phosphate buffer solution, the concentration of the buffer solution is 80-120 nM, and the concentration of sodium acetate in the buffer solution is 1400-1600 mg / L. In step (3), the volume ratio of the sludge sample to the buffer solution is 1:8-10.
7. The method for enhancing hydrogen production through bioelectrofermentation by microplastic depolymerization as described in claim 6, characterized in that, In step (3), the number of cycles of the primary operation is ≥3, and the operation time of a single cycle is 6-8 days. In step (3), the time of the secondary operation is 5-8 days. In step (3), the external voltage of the primary operation and the secondary operation is 0.6-1 V.
8. The method for enhancing hydrogen production through bioelectrofermentation by microplastic depolymerization as described in claim 7, characterized in that, In step (4), the volume ratio of the fermentation liquor to water in the aqueous solution of the fermentation liquor is 1:1-2. The volume of the aging liquor is 1-17% of the volume of the aqueous solution of the fermentation liquor.
9. The method of claim 8, wherein the microplastic depolymerization is enhanced by the bioelectrofermentation. In step (4), the volume of the aging liquor is 5-15% of the volume of the sludge sample in step (3).
10. The method for enhancing hydrogen production through bioelectrofermentation by microplastic depolymerization as described in claim 9, characterized in that, In step (4), the pH is adjusted during the mixing process, and the target value of the adjusted pH is 6.5-7.5.