WO2015143906A1

WO2015143906A1 - A method for improving the methane production rate through acidification pretreatment of hydrogen production of kitchen waste and sludge

Info

Publication number: WO2015143906A1
Application number: PCT/CN2014/095445
Authority: WO
Inventors: 程军; 岑可法; 王智化; 周俊虎; 刘建忠; 黄镇宇; 周志军; 杨卫娟; 张彦威
Original assignee: 浙江大学
Priority date: 2014-03-24
Filing date: 2014-12-29
Publication date: 2015-10-01
Also published as: CN104561222A; CN104561222B

Abstract

Provided is a method for improving the methane production rate through acidification pretreatment of hydrogen production of kitchen waste and sludge. The method comprises: mixing the kitchen waste after crushing pretreatment with sludge, hydrolyzing the mixed solution formulated with sulfuric acid at 135℃ to obtain the fermentation materials, adding yeast powder to the fermentation materials, inoculating the dark fermentation hydrogen producing bacteria, creating the anaerobic fermenting environment by introducing the high purity nitrogen, processing dark deep acidification pretreatment of hydrogen production fermentation at the constant temperature 37℃, adding methanogenic bacteria and maintaining anaerobic environment at 37℃ to ferment and to produce methane.

Description

Method for improving methane production rate by pretreatment of kitchen waste and sludge by hydrogenation

Technical field

The invention relates to a biomass energy utilization technology, in particular to a method for improving the biomethane production rate by deep acid acidification pretreatment of a kitchen waste and sludge mixed fermentation.

Background technique

The increasing shortage of fossil energy and serious environmental pollution are the two major crisis problems facing the world today. The serious impact of the greenhouse effect on the climate environment has caused people to pay more and more attention to the issue of CO ₂ emission reduction. The development of new energy is the inevitable result of China's energy security and sustainable development. Claim. Biomass energy is the most common renewable energy on the planet, and its total consumption ranks first among renewable energy. Urban and rural organic waste is a renewable biomass resource with a large number and serious pollution. How to realize the reduction and harmless treatment of urban and rural waste and the utilization of energy resources is a hot and difficult problem in economic and social development. The use of biomass waste to produce new oil and gas, the production of compressed natural gas by fermentation of hydrogen and methane, used as a clean substitute fuel for automobile engines, is an emerging frontier technology in the field of international energy and environment, in line with the new energy and energy encouraged by China. Strategic emerging industry policies such as energy conservation and environmental protection.

KIM S H and others used a canteen kitchen waste to conduct fermentation and methanogenesis, and obtained fermentation data of 122.9 mL/g carbohydrate. Jae Kyoung et al. conducted a research on the methanation potential (BMP) of kitchen waste. The results showed that kitchen waste had higher anaerobic methanation potential, and the methanation potential of meat, cellulose, rice, cabbage and mixed waste was 482, respectively. The anaerobic biodegradability of 356, 294, 277, 472mL CH4/gVS was 0.82, 0.92, 0.72, 0.73, and 0.86, respectively. However, the long-term stability test was not effective, and the gas production rate was far below the UBMP study results. Yu.Sheng Wan et al. conducted a combined fermentation experiment of kitchen waste and sludge. The results showed that the fermentation of the kitchen waste can proceed smoothly under a certain ratio. Kang et al believe that kitchen waste acidification liquid is the main reason for inhibiting the methanation process of kitchen waste. Ghanem et al. believe that the accumulation of volatile acids will lead to the stagnation of the system's gas production, and the methanation can be continued by reducing the concentration of volatile acids and restoring the gas production capacity of the system. However, there are many types of municipal waste, including kitchen waste, waste water plant and food plant sludge. How to improve the fermentation production process and increase the methane production rate is a technical problem, which is of great significance for energy conservation and emission reduction and development of new energy.

Summary of the invention

The main object of the present invention is to overcome the deficiencies in the prior art and to provide a method for improving the production rate of biomethane by deep acid acidification pretreatment of kitchen waste and sludge mixed fermentation.

In order to solve the above technical problems, the solution of the present invention is:

A method for improving the rate of methane production by preheating pretreatment of kitchen waste and sludge, comprising the following steps:

(1) Mixing the kitchen waste and sludge after the pulverization pretreatment according to a mass ratio of 1:1 to obtain a pretreated raw material; preparing the pretreated raw material with a H ₂ SO ₄ solution having a mass concentration of 1% to prepare a mixed solution, The concentration of the pretreated raw material in the mixed solution is 20-30 g/L; the mixed solution is hydrolyzed at 135 ° C for 15 min;

(2) 200-500 ml of fermentation raw material is added to a fermentation flask having a volume of 600 ml, and the pH is adjusted to 6.4-6.6 with a NaOH having a mass concentration of 6 mol/L; 0.2-0.5 g of yeast powder is added to inoculate a dark fermentation hydrogen-producing bacterium 20~ 50ml, pass high-purity nitrogen for 20min to create an anaerobic fermentation environment, and then perform a deep acidification pretreatment of dark fermentation hydrogen production at a constant temperature of 37 °C to obtain a deep acidification pretreatment liquid for hydrogen production;

(3) Adjusting the hydrogenation deep-acidification pretreatment liquid with a concentration of 6 mol/L NaOH to make the pH 7.9-8.1, adding 20-50 ml methanogens, and maintaining the 37 °C anaerobic environment for fermentation to produce methane.

In the present invention, the kitchen waste in the step (1) is derived from a household living or catering industry; the sludge is derived from a municipal sewage treatment plant or a food processing factory.

In the present invention, in the step (2), the dominant strain of the dark fermentation hydrogen producing bacteria is Clostridium butyricum, which is obtained by separating the anaerobic digestion sludge: the anaerobic digestion sludge is subjected to heat treatment. The methanogens are killed and the spores of the dark fermentative hydrogen producing bacteria are retained, and the culture is enriched three times, once every 72 hours.

In the present invention, in the step (3), the dominant species of the methanogens are Methanosarcina and Methanothrix, which are anaerobic activated sludge of the biogas digester without heat treatment. It is obtained by multiple enrichment and culture in the incubator.

The invention significantly increases the production rate of biomethane by deep acidification pretreatment of dark fermentation hydrogen production.

The gas and methane components in the fermentation gas can be tested using a gas chromatograph equipped with a thermal conductivity detector; the gas chromatograph operating parameters are: inlet temperature 200 ° C, detector temperature 300 ° C, initial oven temperature 65 °C. The oven temperature in the experiment was programmed for a total time of 6 minutes, the initial temperature was 65 ° C, held for 1 minute, then the heating rate was set to 25 ° C / min, after 3.2 minutes until the final temperature reached 145 ° C, and then continue to maintain 1.8 minutes. The flow rate of the carrier gas argon gas was 27 ml/min.

Compared with the prior art, the beneficial effects of the present invention are:

Mixing of kitchen waste and sludge through the deep acidification pretreatment of hydrogen production significantly increases the methane production rate, reducing the peak time of methane production by about 50%, thus reducing the treatment degradation time of waste per unit volume of fermenter equipment by about 50. %, which allows a single device to double the amount of waste processed per unit of time.

DRAWINGS

Figure 1 is a process flow diagram of the present invention.

detailed description

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

As shown in FIG. 1 , the method for improving the methane production rate by the pretreatment of the kitchen waste and the sludge hydro-acidification comprises the following steps:

(1) After pre-treating the kitchen waste and sludge, the mixture is mixed at a mass ratio of 1:1 to obtain a pretreated raw material. Then, with a mass concentration of 1% H ₂ SO ₄ solution, a mixed liquid with a pretreatment raw material concentration of 20-30 g/L is prepared, and the mixed solution is hydrolyzed at a high temperature of 135 ° C for 15 minutes to obtain a fermentation raw material; the kitchen waste can be a resident. The kitchen waste produced in daily life or the kitchen waste produced by the catering industry may be sludge from municipal sewage treatment plants or sludge from food factories;

(2) 200 to 500 ml of the fermented raw material subjected to high temperature treatment is added to a fermentation flask having a volume of 600 ml, and the pH is adjusted to 6.4 to 6.6 with a NaOH having a mass concentration of 6 mol/L. Add 0.2-0.5g yeast powder, inoculate 20~50ml of dark fermentation hydrogen-producing bacteria, and pass high-purity nitrogen for 20min to create an anaerobic fermentation environment, then carry out deep acidification pretreatment of dark fermentation by constant temperature at 37 °C to obtain deep acidification pretreatment of hydrogen production. Treatment liquid; wherein, yeast powder refers to concentrated yeast leaching powder, purchased from Fuyang City, Zhejiang Province, Hangzhou Fu Biological Products Factory;

The dark fermentation hydrogen-producing bacteria are collected from anaerobic digestion sludge, and the sludge is heated to kill the methanogen to retain the spores of the dark fermentation hydrogen-producing bacteria, and the culture is enriched three times (every 72 hours) to obtain the dominant species. Clostridium butyricum.

(3) For the deep acidification pretreatment liquid, the pH is adjusted to 7.9-8.1 with NaOH with a mass concentration of 6 mol/L, 20-50 ml of methanogens are added, and the anaerobic environment at 37 °C is maintained for fermentation to produce methane.

Among them, the methanogens are obtained by enriching the biogas digesters without heat treatment in the anaerobic incubator, and the dominant species are Methanosarcina and Methanothrix.

The present invention can test hydrogen and methane components in a fermentation gas using a gas chromatograph equipped with a thermal conductivity detector. The gas chromatograph operating parameters are: inlet temperature 200 ° C, detector temperature 300 ° C, initial oven temperature 65 ° C. The oven temperature in the experiment was programmed for a total time of 6 minutes, the initial temperature was 65 ° C, held for 1 minute, then the heating rate was set to 25 ° C / min, after 3.2 minutes until the final temperature reached 145 ° C, and then continue to maintain 1.8 minutes. The flow rate of the carrier gas argon gas was 27 ml/min.

Example 1

After pre-treating the kitchen waste and the sludge, the mixture is mixed at a mass ratio of 1:1 to obtain a pretreated raw material. Then, with a mass concentration of 1% H ₂ SO ₄ solution, a mixture of pretreatment raw material concentration of 20g / L is prepared, and the mixture is hydrolyzed at a high temperature of 135 ° C for 15 minutes to obtain a fermentation raw material; 200 ml of the fermentation raw material is added to a volume of 600 ml. The fermentation flask was adjusted to a pH of 6.4 with a mass concentration of 6 mol/L NaOH. Add 0.2g of yeast powder, inoculate 20ml of dark fermentation hydrogen-producing bacteria, and pass high-purity nitrogen for 20min to create an anaerobic fermentation environment, then carry out dark fermentation acidification deep-acidification pretreatment at 37 °C; dark fermentation hydrogen production bacteria collected from anaerobic digestion The sludge is separated, and the sludge is heated to kill the methanogen to retain the spores of the dark fermentation hydrogen-producing bacteria, and the culture is enriched three times (every 72 hours) to obtain the dominant species is Clostridium butyricum. The hydrogenation deep acidification pretreatment liquid was adjusted to pH 7.9 with a concentration of 6 mol/L NaOH, 20 ml of methanogen was added, and the anaerobic environment was maintained at 37 ° C for fermentation to produce methane, and the biomethane was pretreated by deep acidification of hydrogen production. Production rates have increased by 51%. The methanogens were obtained from the biogas digesters without heat treatment, and were enriched and cultured in an anaerobic incubator, mainly M. mazei and M. thermomycetes.

The hydrogen and methane components in the fermentation gas were tested using a gas chromatograph equipped with a thermal conductivity detector (purchased in Agilent 7820A, USA). The gas chromatograph operating parameters are: inlet temperature 200 ° C, detector temperature 300 ° C, initial oven temperature 65 ° C. The oven temperature in the experiment was programmed for a total time of 6 minutes, the initial temperature was 65 ° C, held for 1 minute, then the heating rate was set to 25 ° C / min, after 3.2 minutes until the final temperature reached 145 ° C, and then continue to maintain 1.8 minutes. The flow rate of the carrier gas argon gas was 27 ml/min.

Example 2

After pre-treating the kitchen waste and the sludge, the mixture is mixed at a mass ratio of 1:1 to obtain a pretreated raw material. Then, with a mass concentration of 1% H ₂ SO ₄ solution to prepare a mixture of pretreatment raw material concentration of 25g / L, the mixture is hydrolyzed at a high temperature of 135 ° C for 15min to obtain a fermentation raw material; 300ml of high temperature treated mixture A ferment bottle having a volume of 600 ml was added, and the pH of the mixture was adjusted to 6.5 with a NaOH having a mass concentration of 6 mol/L. Add 0.3g of yeast powder, inoculate 30ml of dark fermentation hydrogen-producing bacteria, and pass high-purity nitrogen for 20min to create an anaerobic fermentation environment, then conduct a dark fermentation at pH 37 °C for deep acidification. The dark fermentation hydrogen-producing bacteria are collected from anaerobic digestion. The sludge is separated, and the sludge is heated to kill the methanogen to retain the spores of the dark fermentation hydrogen-producing bacteria, and the culture is enriched three times (every 72 hours) to obtain the dominant species is Clostridium butyricum. The hydrogenation deep acidification pretreatment liquid was adjusted to pH 8.0 with a concentration of 6 mol/L NaOH, 30 ml of methanogen was added, and the anaerobic environment was maintained at 37 ° C for fermentation to produce methane, and the deep acidification pretreatment of dark hydrogen by dark fermentation made the organism The production rate of methane has increased by 55%. The methanogens were obtained from the biogas digesters without heat treatment, and were enriched and cultured in an anaerobic incubator, mainly M. mazei and M. thermomycetes.

Example 3

After pre-treating the kitchen waste and the sludge, the mixture is mixed at a mass ratio of 1:1 to obtain a pretreated raw material. Then, with a mass concentration of 1% H ₂ SO ₄ solution, a mixture of pretreatment raw material concentration of 30 g / L is prepared, and the mixture is hydrolyzed at a high temperature of 135 ° C for 15 min to obtain a fermentation raw material; 500 ml of the high temperature treated mixture is obtained. A ferment bottle having a volume of 600 ml was added, and the pH of the mixture was adjusted to 6.6 with a NaOH having a mass concentration of 6 mol/L. Add 0.5g of yeast powder, inoculate 50ml of dark fermentation hydrogen-producing bacteria, and pass high-purity nitrogen for 20min to create an anaerobic fermentation environment, then carry out dark fermentation to deep acidification pre-treatment at 37 °C; dark fermentation hydrogen-producing bacteria collected from anaerobic digestion The sludge is separated, and the sludge is heated to kill the methanogen to retain the spores of the dark fermentation hydrogen-producing bacteria, and the culture is enriched three times (every 72 hours) to obtain the dominant species is Clostridium butyricum. The hydrogenation deep acidification pretreatment liquid was adjusted to pH 8.1 with a concentration of 6 mol/L NaOH, 50 ml of methanogen was added, and the anaerobic environment was maintained at 37 ° C for fermentation to produce methane, and the deep acidification pretreatment of dark hydrogen by dark fermentation made the organism The production rate of methane has increased by 48%. The methanogens were obtained from the biogas digesters without heat treatment, and were enriched and cultured in an anaerobic incubator, mainly M. mazei and M. thermomycetes.

Finally, it should be noted that the above enumerated are only specific embodiments of the invention. It is apparent that the present invention is not limited to the above embodiment, and many variations are possible. All modifications that can be directly derived or referenced by those skilled in the art from this disclosure are considered to be the scope of the invention.

Claims

The method for improving the methane production rate by the pretreatment of the kitchen waste and the sludge by hydrogenation is characterized in that the following steps are specifically included:

(1) Mixing the kitchen waste and sludge after the pulverization pretreatment according to a mass ratio of 1:1 to obtain a pretreated raw material; preparing the pretreated raw material with a H 2 SO 4 solution having a mass concentration of 1% to prepare a mixed solution, The concentration of the pretreated raw material in the mixed solution is 20-30 g/L; the mixed solution is hydrolyzed at 135 ° C for 15 min to obtain a fermentation raw material;

(2) 200-500 ml of fermentation raw material is added to a fermentation flask having a volume of 600 ml, and the pH is adjusted to 6.4-6.6 with a NaOH having a mass concentration of 6 mol/L; 0.2-0.5 g of yeast powder is added to inoculate a dark fermentation hydrogen-producing bacterium 20~ 50ml, pass high-purity nitrogen for 20min to create an anaerobic fermentation environment, and then perform a deep acidification pretreatment of dark fermentation hydrogen production at a constant temperature of 37 °C to obtain a deep acidification pretreatment liquid for hydrogen production;

(3) Adjusting the hydrogenation deep-acidification pretreatment liquid with a concentration of 6 mol/L NaOH to make the pH 7.9-8.1, adding 20-50 ml methanogens, and maintaining the 37 °C anaerobic environment for fermentation to produce methane.
The method according to claim 1, wherein the kitchen waste in the step (1) is derived from a resident family life or a catering industry; and the sludge is derived from a municipal sewage treatment plant or a food processing factory.
The method according to claim 1, wherein in the step (2), the dominant species of the dark fermentation hydrogen producing bacteria is Clostridium butyricum, which is obtained by separating anaerobic digestion sludge: The anaerobic digestion sludge is heat treated to kill the methanogens and retain the spores of the dark fermentation hydrogen producing bacteria, and the culture is enriched three times, once every 72 hours.
The method according to claim 1, wherein in the step (3), the dominant species of the methanogens are M. mazei and M. sphaeroides, which are biogas digester activities which are not subjected to heat treatment. The sludge is enriched and cultured several times in an anaerobic incubator.