CN110760353A

CN110760353A - Method for producing clean energy by utilizing kitchen waste

Info

Publication number: CN110760353A
Application number: CN201911058412.XA
Authority: CN
Inventors: 谢耀明
Original assignee: Hunan 352 Environmental Protection & Technology Co Ltd
Current assignee: Hunan 352 Environmental Protection & Technology Co Ltd
Priority date: 2019-11-01
Filing date: 2019-11-01
Publication date: 2020-02-07
Anticipated expiration: 2039-11-01
Also published as: CN110760353B

Abstract

The invention discloses a method for producing clean energy by utilizing kitchen waste, which comprises the steps of sorting and screening collected coarse solids and gravels in the kitchen waste, performing microwave heating pretreatment, sedimentation in a first primary sedimentation tank and sedimentation in a second primary sedimentation tank to obtain waste activated sludge and primary sewage sludge, centrifuging the waste activated sludge, performing hydrothermal carbonization on the waste activated sludge, centrifuging the waste activated sludge to obtain wet hydrothermal carbon and hydrothermal carbonization liquid, performing acid production treatment on the hydrothermal carbonization liquid and the primary sewage sludge, transferring the hydrothermal carbonization liquid and the primary sewage sludge to a leachate bed reactor, performing light fermentation degradation and methane production anaerobic digestion reaction to obtain biogas and hydrogen, and drying the wet hydrothermal carbon by a solar dryer to be used as a high-energy environment-friendly biofuel energy. The method of the invention improves the digestibility in the anaerobic digestion process, further reduces the residual amount of the digestion residues, and can obtain hydrothermal carbon, methane and hydrogen which are used as biofuel energy, thereby recycling the energy.

Description

Method for producing clean energy by utilizing kitchen waste

Technical Field

The invention relates to the technical field of sewage sludge treatment, in particular to a method for producing clean energy by utilizing kitchen waste.

Background

Kitchen waste, commonly known as swill, also known as hogwash and swill, is mainly generated in catering industry, dining halls and families, and mainly refers to domestic sewage and waste which is easy to rot and deteriorate and is generated by eating behaviors of people. Compared with other garbage, the garbage has the characteristics of high water content, high grease content and high inorganic salt content. The kitchen waste accounts for a large proportion of municipal domestic waste, and is a high-quality harmful organism culture medium which is a byproduct of human beings, so that mosquito, fly and germ can be easily and spontaneously bred, toxic, stink and combustible gas can be generated, and fire-fighting hidden dangers and environmental protection and public health problems can be caused. The waste oil and swill pig which improperly utilize the kitchen waste have great harm, and the kitchen waste is an available resource due to rich oil and other organic matter content and higher heat value after dehydration.

The method comprises the following steps of non-biological treatment and biological treatment according to treatment media: wherein the non-biological treatment comprises mechanical crushing, sanitary landfill, incineration power generation, gasification and the like; the biological treatment comprises anaerobic fermentation, aerobic fermentation, ecological feed preparation and the like.

At present, the kitchen waste treatment technology in China mainly comprises anaerobic digestion, aerobic treatment, feed conversion and the like. Anaerobic digestion is a mainstream technology, and is popular due to mature technology, but the requirements on pretreatment technology and debugging are high, the resource conversion rate is low, and the treatment burden of the kitchen waste cannot be really solved. The aerobic fermentation has the advantages of short treatment period, high recycling turnover rate of garbage, small occupied area of projects, reduction rate of more than 95 percent, safe treatment process and no secondary pollution to the environment. The development of feed is hindered by safety problems such as homology and the like. Hydrothermal carbonization is a new type of carbon-based material which takes water as a medium and converts biological substances into high-value-added multifunctional carbon-based materials at high temperature and high pressure, and has the advantage of converting wastes into energy resources.

Chinese patent 201410031722.3 discloses a comprehensive treatment method of domestic garbage based on anaerobic digestion and hydrothermal carbonization, which comprises the steps of performing serous treatment, anaerobic digestion, hydrothermal carbonization and dehydration drying respectively to comprehensively treat the domestic garbage, and finally obtaining biogas and stable hydrothermal carbon in the form of carbon element.

Disclosure of Invention

The invention provides a method for producing clean energy by utilizing kitchen waste, which has the advantages of high hydrothermal carbon conversion rate and yield, capability of effectively utilizing the kitchen waste, high anaerobic digestion rate, high energy recovery rate and capability of simultaneously generating hydrogen and methane.

In order to achieve the purpose, the invention provides the following technical scheme: a method for producing clean energy by utilizing kitchen waste comprises the following steps:

1) sorting the collected kitchen waste by using a sorting device to sort coarse solid waste, and screening out silt and gravel by using a screen;

2) transferring the mixture obtained in the step 1) to a microwave heating pretreatment pool for pretreatment;

3) transferring the pretreated mixture obtained in the step 2) to a first primary sedimentation tank for sedimentation;

4) transferring the first primary sedimentation sludge obtained after primary sedimentation in the first primary sedimentation tank in the step 3) to a second primary sedimentation tank for sedimentation, wherein the sludge obtained by sedimentation is primary sewage sludge;

5) mixing the first primary settling supernatant obtained after the primary settling in the first primary settling tank in the step 3) with the second primary settling supernatant obtained after the primary settling in the second primary settling tank in the step 4) to obtain waste activated sludge;

6) dehydrating the waste activated sludge obtained in the step 5) by using a first centrifuge to obtain dehydrated waste activated sludge;

7) adding the dehydrated waste activated sludge obtained in the step 6) into a hydrothermal carbonization kettle, and carrying out hydrothermal carbonization reaction under the condition that the temperature in the hydrothermal carbonization kettle is stably increased at the speed of 3-5 ℃/min to the final temperature of 200-210 ℃, and keeping the final temperature for 1-1.2 h to obtain hydrothermal carbonization slurry; centrifuging the hydrothermal carbonized slurry by a second centrifuge to obtain a hydrothermal carbonized liquid and wet hydrothermal carbon;

8) performing acid production treatment on the hydrothermal carbonization liquid obtained in the step 7) and the primary sewage sludge obtained in the step 4), transferring the obtained mixture to a leachate bed reactor for anaerobic fermentation treatment, adding 1M NaOH to adjust the pH value of the initial reaction to 6.5-7.5, adding light fermentation degrading bacteria and methanogenic bacteria into the leachate bed reactor for hydrogen production and methane production reaction, and circulating the obtained hydrogen and methane in the leachate bed reactor during anaerobic fermentation, wherein the obtained hydrogen and methane can be used as biological clean energy after being collected; the reaction time of the leachate bed reactor is 12-15 days.

9) And (3) drying the wet hydrothermal carbon obtained in the step 6) by using a solar dryer to obtain dry hydrothermal carbon, wherein the dry hydrothermal carbon can be used as a high-energy environment-friendly biofuel energy.

As a further limitation of the present invention, the leachate bed reactor comprises a sprayer disposed at an inlet at an upper portion, a filter screen, a solid waste holding area disposed at an upper portion of the filter screen, a filtrate collecting area at a lower portion of the filter screen, a first peristaltic pump for circulating a filtrate, a filtrate circulating pipe, a gas circulating pipe, and a second peristaltic pump for circulating a gas.

As a further limitation of the present invention, after the hydrothermal carbonization liquid and the primary sewage sludge in the step 8) are mixed with each other, acid production treatment is performed and the mixture is transferred to a solid waste containing area of the leachate bed reactor, the hydrothermal carbonization liquid leaks to the filtrate collecting area through the filter screen, and then is circulated to the solid waste containing area through the sprayer and the filtrate circulating pipe to be permeated and mixed with the primary sewage sludge, and hydrogen and methane generated by the anaerobic fermentation reaction are circulated in the leachate bed reactor through the gas circulating pipe and the second peristaltic pump.

As a further limitation of the invention, the photo-fermentation degrading bacteria are added to the solid waste holding area, and the methanogen is added to the filtrate collecting area.

As a further limitation of the present invention, the hydrothermal carbonization liquid in the step 8) and the primary sewage sludge are subjected to acid production treatment, the hydrothermal carbonization liquid in the step 8) is transferred to the filtrate collection region, the primary sewage sludge is transferred to the solid waste holding region, the hydrothermal carbonization liquid is circulated to the solid waste holding region through a sprayer, a filtrate circulation pipe and a first peristaltic pump to be subjected to osmotic mixing with the primary sewage sludge, an anaerobic fermentation reaction occurs, and hydrogen and methane generated by the anaerobic fermentation reaction circulate in the leachate bed reactor 9 through the gas circulation pipe 97 and the second peristaltic pump 98.

As a further limitation of the invention, the light fermentation degrading bacteria are added to the filtrate collecting zone and the methanogen is added to the solid waste holding zone.

As a further limitation of the invention, the acid production treatment in the step 8) is to add one or more of lactobacillus, lactobacillus acidophilus, clostridium butyricum and bacillus aceticus, and to maintain the temperature at 30-35 ℃ for 24-36 h.

As a further limitation of the invention, the light fermentation degrading bacteria added in the step 8) are one or more of rhodopseudomonas, pseudomonas alcaligenes, rhodobacter capsulatus and rhodobacter sphaeroides, and the light fermentation degrading conditions are that the temperature is maintained at 29-31 ℃ and the illumination intensity is 4500-6500 lx.

As a further limitation of the invention, the methanogenic bacteria added in the step 8) are methanobacterium formate, methanosarcina methanolica and methanotrophic bacteria, and the condition of methane-producing anaerobic fermentation is to maintain the pH at 8-8.5 and the temperature at 30-35 ℃.

As a further limitation of the invention, the leachate bed reactor is also added with photocatalytic nano-particles ZnO, CdS and WO₃、SnO₂、SiC、TiO₂One or more of the photocatalytic degradation bacteria are used for enhancing the degradation efficiency of the photocatalytic degradation bacteria.

The invention has the beneficial effects that:

1. the quality of hydrothermal carbon produced by hydrothermal carbonization can be effectively improved by selecting the dewatered waste activated sludge as a substrate of the hydrothermal carbonization reaction instead of a mixture of primary sewage sludge and waste activated sludge as the substrate, because the dewatered waste activated sludge has less ash content compared with the kitchen waste which is not subjected to separated original rough treatment, and because the waste activated sludge contains higher phosphorus content, the hydrothermal carbonization treatment is carried out on the waste activated sludge obtained after primary twice sedimentation, the hydrothermal carbon with higher phosphorus content can be obtained, and the improvement capability of the hydrothermal carbon as a soil improvement matrix is further improved.

2. The primary sewage sludge and the waste activated sludge are settled and separated, organic matters in the waste activated sludge can be preferentially utilized for hydrothermal carbonization, organic carbon is converted into hydrothermal carbon for solidification, high-quality carbon energy is reserved, and the hydrothermal carbonization liquid obtained after the hydrothermal carbonization treatment and the primary sewage sludge are subjected to anaerobic digestion treatment, so that the anaerobic digestion of organic matters in the hydrothermal carbonization liquid can be improved by utilizing active microorganisms in the primary sewage sludge, and the anaerobic digestion rate of kitchen waste in an anaerobic digestion part is improved.

3. The hydrothermal carbonization process of the kitchen waste is controllably treated, the temperature is slowly increased, the uniformity of the material can be increased, and the uniformly distributed carbon balls or carbon particles with moderate and uniform sizes are formed.

4. For H generated in the anaerobic fermentation process₂And CH₄The leachate bed reactor is internally circulated, so that the effect of continuously providing an anaerobic environment for a light fermentation degradation process and an anaerobic fermentation process can be achieved, and the final H can be improved₂And CH₄The yield of the product is increased, and the energy recovery rate is increased.

5. The anaerobic fermentation process is characterized in that acid production treatment is carried out firstly, soluble substances can be generated before hydrogen and methane are generated by anaerobic fermentation of methanogens through photodegradation fermentation, so that the processes of hydrogen production through photodegradation fermentation and anaerobic fermentation of methanogens are accelerated, the efficiency of hydrogen production through photodegradation and anaerobic fermentation is improved, macromolecular organic substances in kitchen waste are effectively utilized, and H is increased₂And CH₄The yield of (2).

6. The microwave heating pretreatment is carried out on the sorted and filtered primary kitchen waste, so that the primary decomposition of the kitchen waste can be increased, the grease in the kitchen waste can be decomposed into micromolecular grease particles, meanwhile, the part rich in cellulose in the kitchen waste is decomposed in advance, the contact between the cellulose and cellulase is increased, the efficiency of photodegradation fermentation and methanogen anaerobic digestion is increased, and the heat value conversion efficiency of converting the waste into the biofuel is improved.

Drawings

FIG. 1 is a process flow diagram of a method for producing clean energy by using kitchen waste according to the present invention;

fig. 2 is a schematic structural diagram of equipment for product treatment at each stage of the method for producing clean energy from kitchen waste, provided by embodiments 1 and 4 of the present invention;

fig. 3 is a schematic structural diagram of equipment used for product treatment at each stage of the method for producing clean energy from kitchen waste, provided by

embodiments

2 and 3 of the present invention.

In the figure: 1. a sorting device; 2. screening a screen; 3. a first primary sedimentation tank; 4. an aeration tank; 5. a second primary sedimentation tank; 6. a first centrifuge; 7. a hydrothermal carbonization kettle; 8. a second centrifuge; 9. a leachate bed reactor; 91. a sprayer; 92. filtering with a screen; 93. a solid waste holding area; 94. a filtrate collecting area; 95. a first peristaltic pump; 96. a filtrate circulation pipe; 97. a gas circulation pipe; 98, respectively; a second peristaltic pump; 10, a solar dryer; 11. a first acid-producing treatment tank; 12. a second acid-producing treatment tank.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Referring to fig. 1-2, the method for producing clean energy by using kitchen waste of the present invention comprises the following steps:

1) sorting the collected kitchen waste by using a sorting device 1 to sort coarse solid waste, and screening silt and gravel by using a screen 2;

2) transferring the mixture obtained in the step 1) to a microwave heating pretreatment pool 3 for pretreatment;

3) transferring the pretreated mixture obtained in the step 2) to a first primary sedimentation tank 4 for sedimentation;

4) transferring the first primary sludge obtained after primary sedimentation in the first primary sedimentation tank 4 in the step 3) to a second primary sedimentation tank 5 for sedimentation, wherein the sludge obtained by sedimentation is primary sewage sludge;

5) mixing the first primary sedimentation supernatant obtained after the primary sedimentation in the first primary sedimentation tank 4 in the step 3) with the second primary sedimentation supernatant obtained after the primary sedimentation in the second primary sedimentation tank 5 in the step 4) to obtain waste activated sludge;

6) dehydrating the waste activated sludge obtained in the step 5) by using a first centrifuge 6 to obtain dehydrated waste activated sludge;

7) adding the dehydrated waste activated sludge obtained in the step 6) into a hydrothermal carbonization kettle 7, and carrying out hydrothermal carbonization reaction under the condition that the temperature in the hydrothermal carbonization kettle 7 is stably increased at the speed of 3 ℃/min to the final temperature of 200 ℃, and keeping the final temperature for 1h to obtain hydrothermal carbonization slurry; the hydrothermal carbonization slurry is centrifuged by a second centrifuge 8 to obtain hydrothermal carbonization liquid and wet hydrothermal carbon;

8) mixing the hydrothermal carbonization liquid obtained in the step 7) and the primary sewage sludge obtained in the step 4), performing acid production treatment in a first acid production treatment tank 11, transferring the mixture to a solid waste containing area 93 of a leachate bed reactor 9, and performing anaerobic fermentation treatment, wherein in the anaerobic fermentation treatment process, the hydrothermal carbonization liquid leaks to a filtrate collecting area 94 through a filter screen 92, and then is circulated to the solid waste containing area 93 through a sprayer 91, a filtrate circulating pipe 96 and a first peristaltic pump 95 to be subjected to osmotic mixing with the primary sewage sludge;

wherein, lactic acid bacteria and clostridium butyricum are added in the acid production treatment process, the temperature is maintained at 30 ℃, and the treatment is carried out for 24 hours;

in the anaerobic fermentation treatment process, 1M NaOH is added to adjust the pH value of the initial reaction to 6.5, and photo-fermentation degrading bacteria, namely rhodopseudomonas and rhodobacter sphaeroides and photo-catalysis nano particles ZnO and SnO are added into a solid waste containing area 93 of the leachate bed reactor 9₂And TiO₂The light fermentation degradation condition is that the temperature is maintained at 29 ℃, the illumination intensity is 4500lx,

methanogens, methanobacter formate and methanotrophic bacteria are also added into the filtrate collection zone 94 of the leachate bed reactor 9, the methane-producing anaerobic fermentation condition is to maintain the pH at 8 and the temperature at 30 ℃,

and hydrogen production and methane production are carried out for 12 days, the obtained hydrogen and methane circulate in the leachate bed reactor 9 through the gas circulation pipe 97 and the second peristaltic pump 98, and the hydrogen and the methane can be used as biological clean energy after being collected.

9) And (3) drying the wet hydrothermal carbon obtained in the step 6) by using a solar dryer 10 to obtain dry hydrothermal carbon, wherein the dry hydrothermal carbon can be used as a high-energy environment-friendly biofuel energy.

Example 2

Referring to fig. 1 and 3, the method for producing clean energy by using kitchen waste provided by the invention comprises the following steps:

1) sorting the collected kitchen waste by using a sorting device 1, and screening silt and gravel by using a screen (2);

5) mixing the first primary settling supernatant obtained after the primary settling in the first primary settling tank (4) in the step 3) with the second primary settling supernatant obtained after the primary settling in the second primary settling tank 5 in the step 4) to obtain waste activated sludge;

7) adding the dehydrated waste activated sludge obtained in the step 6) into a hydrothermal carbonization kettle 7, and carrying out hydrothermal carbonization reaction under the condition that the temperature in the hydrothermal carbonization kettle (7) is stably increased at the speed of 4.5 ℃/min to reach the final temperature of 207 ℃, and keeping the final temperature for 1.16h to obtain hydrothermal carbonization slurry; the hydrothermal carbonization slurry is centrifuged by a second centrifuge 8 to obtain hydrothermal carbonization liquid and wet hydrothermal carbon;

8) performing acid production treatment on the hydrothermal carbonization liquid obtained in the step 7) in a second acid production treatment tank 12, and performing acid production treatment on the primary sewage sludge obtained in the step 4) in a first acid production treatment tank 11; adding lactic acid bacteria into the first acid production treatment tank, maintaining the temperature at 33 ℃, and treating for 34h, adding clostridium butyricum into the second acid production treatment tank, maintaining the temperature at 334.5 ℃, and treating for 35 h;

transferring the hydrothermal carbonization liquid subjected to acid production treatment to a filtrate collecting region 94, transferring the primary sewage sludge subjected to acid production treatment to a solid waste containing region 93, circulating the hydrothermal carbonization liquid to the solid waste containing region 93 through a sprayer 91, a filtrate circulating pipe 96 and a first peristaltic pump 95 to perform osmotic mixing with the primary sewage sludge to perform anaerobic fermentation reaction,

adding 1M NaOH to adjust the pH value of the initial reaction to 7.35 in the anaerobic fermentation reaction process, adding light fermentation degrading bacteria-encapsulated rhodobacter in a filtrate collecting region 94 of the percolate bed reactor 9, and carrying out light fermentation degrading hydrogen production reaction with the filtrate collecting region 94 under the reaction conditions that the temperature is maintained at 29.5 ℃ and the illumination intensity is 5800 lx;

methanogens-methanotrophic bacteria are added into a solid waste containing area 93 of the percolate bed reactor 9 for methanogenic reaction, and the condition of methane-producing anaerobic fermentation is to maintain the pH value at 8.2 and the temperature at 33 ℃;

and hydrogen production and methane production are carried out for 13 days, the obtained hydrogen and methane circulate in the leachate bed reactor 9 through the gas circulation pipe 97 and the second peristaltic pump 98, and the hydrogen and the methane can be used as biological clean energy after being collected.

9) And (3) drying the wet hydrothermal carbon obtained in the step 6) by using a solar dryer (10) to obtain dry hydrothermal carbon, wherein the dry hydrothermal carbon can be used as a high-energy environment-friendly biofuel energy.

Example 3

7) adding the dehydrated waste activated sludge obtained in the step 6) into a hydrothermal carbonization kettle 7, and carrying out hydrothermal carbonization reaction under the condition that the temperature in the hydrothermal carbonization kettle (7) is stably increased at the speed of 3.8 ℃/min to reach the final temperature of 204 ℃, and keeping the final temperature for 1.07h to obtain hydrothermal carbonization slurry; the hydrothermal carbonization slurry is centrifuged by a second centrifuge 8 to obtain hydrothermal carbonization liquid and wet hydrothermal carbon;

8) performing acid production treatment on the hydrothermal carbonization liquid obtained in the step 7) in a second acid production treatment tank 12, and performing acid production treatment on the primary sewage sludge obtained in the step 4) in a first acid production treatment tank 11; the reaction conditions of the first acid-producing treatment tank and the second acid-producing treatment tank are both that acetobacter is added, the temperature is maintained at 32 ℃, and the treatment is carried out for 28 hours;

adding 1M NaOH to adjust the pH value of the initial reaction to 6.8 in the anaerobic fermentation reaction process, adding light fermentation degrading bacteria-rhodopseudomonas into a filtrate collecting region 94 of a percolate bed reactor 9, and carrying out light fermentation degrading hydrogen production reaction with the filtrate collecting region 94 under the reaction conditions that the temperature is maintained at 30.5 ℃ and the illumination intensity is 6200 lx;

adding methanogen-methanosarcina sarcina to a solid waste containing area 93 of the leachate bed reactor 9 to perform methanogenesis reaction, wherein the methanogenesis anaerobic fermentation condition is to maintain the pH at 8.35 and the temperature at 34 ℃;

and hydrogen production and methane production are carried out for 14 days, the obtained hydrogen and methane are circulated in the leachate bed reactor 9 through the gas circulation pipe 97 and the second peristaltic pump 98, and the hydrogen and the methane can be used as biological clean energy after being collected.

Example 4

Referring to the attached drawings 1-2, the method for producing clean energy by using kitchen waste comprises the following steps:

7) adding the dehydrated waste activated sludge obtained in the step 6) into a hydrothermal carbonization kettle 7, and carrying out hydrothermal carbonization reaction under the condition that the temperature in the hydrothermal carbonization kettle 7 is stably increased at the speed of 5 ℃/min to the final temperature of 210 ℃, and keeping the final temperature for 1.2h to obtain hydrothermal carbonization slurry; the hydrothermal carbonization slurry is centrifuged by a second centrifuge 8 to obtain hydrothermal carbonization liquid and wet hydrothermal carbon;

8) mixing the hydrothermal carbonization liquid obtained in the step 7) and the primary sewage sludge obtained in the step 4), performing acid production treatment in a first acid production tank 11, transferring the mixture to a solid waste containing area 93 of a leachate bed reactor 9, and performing anaerobic fermentation treatment, wherein in the anaerobic fermentation treatment process, the hydrothermal carbonization liquid leaks to a filtrate collecting area 94 through a filter screen 92, and then is circulated to the solid waste containing area 93 through a sprayer 91 and a filtrate circulating pipe 95 to be subjected to osmotic mixing with the primary sewage sludge;

wherein, lactobacillus acidophilus is added in the acid production treatment process, the temperature is maintained at 35 ℃, and the treatment is carried out for 36 hours;

in the anaerobic fermentation treatment process, 1M NaOH is added to adjust the pH value of the initial reaction to 7.5, and a solid waste containing area 93 of the percolate bed reactor 9 is added with a light fermentation degrading bacterium, namely, alcaligenes pseudomonad and a photocatalysis nano particle WO₃And SnO₂The light fermentation degradation condition is that the temperature is maintained at 31 ℃, the illumination intensity is 6500lx,

methanogen-methanosarcina sarcina is also added into the filtrate collection area 94 of the leachate bed reactor 9, the condition of methanogen anaerobic fermentation is that the pH value is maintained at 8.5, the temperature is 35 ℃,

and hydrogen production and methane production are carried out for 15 days, hydrogen and methane generated by anaerobic fermentation reaction circulate in the leachate bed reactor 9 through the gas circulation pipe 97 and the second peristaltic pump 98, and can be used as biological clean energy after being collected.

Comparative example 1

The hydrothermal carbon obtained by treating the kitchen waste by the methods of the embodiments 1 to 4 of the present invention and the hydrothermal carbon obtained in the embodiment 1 of the chinese patent 201410031722.3 are used as comparative examples, and the yield, the mesoporous rate and the phosphorus content are measured, and the test results are shown in table 1.

TABLE 1

Index (I)	Example 1	Example 2	Example 3	Example 4	Comparative example 1
						Yield of	81.26％	85.54％	86.73％	90.54％	60.76％
Rate of mesopores	76.29％	83.09％	84.79％	89.34％	51.75％
						Percentage of phosphorus	59.00％	63.19％	64.23％	67.69％	20.16％

Comparative example 2

The kitchen waste is treated by the methods of the embodiments 1 to 4 of the invention, and the hydrogen and methane yield and yield obtained by the embodiment 1 of the Chinese patent 201811082592.0 are increased. The results are shown in Table 2.

TABLE 2

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A method for producing clean energy by utilizing kitchen waste is characterized by comprising the following steps:

1) sorting the collected kitchen waste by using a sorting device (1) to sort coarse solid waste in the kitchen waste, and screening silt and gravel by using a screen (2);

2) transferring the mixture obtained in the step 1) to a microwave heating pretreatment pool (3) for pretreatment;

3) transferring the pretreated mixture obtained in the step 2) to a first primary sedimentation tank (4) for sedimentation;

4) transferring the first primary sludge obtained after primary sedimentation in the first primary sedimentation tank (4) in the step 3) to a second primary sedimentation tank (5) for sedimentation, wherein the sludge obtained by sedimentation is primary sewage sludge;

5) mixing the first primary settling supernatant obtained after the primary settling in the first primary settling tank (4) in the step 3) with the second primary settling supernatant obtained after the primary settling in the second primary settling tank (5) in the step 4) to obtain waste activated sludge;

6) dehydrating the waste activated sludge obtained in the step 5) by using a first centrifuge (6) to obtain dehydrated waste activated sludge;

7) adding the dehydrated waste activated sludge obtained in the step 6) into a hydrothermal carbonization kettle (7) for hydrothermal carbonization reaction, wherein the hydrothermal carbonization reaction is carried out under the condition that the temperature in the hydrothermal carbonization kettle (7) is stably increased at the speed of 3-5 ℃/min to the final temperature of 200-210 ℃, and the final temperature is kept for 1-1.2 h to obtain hydrothermal carbonization slurry; the hydrothermal carbonization slurry is centrifuged by a second centrifuge (8) to obtain hydrothermal carbonization liquid and wet hydrothermal carbon;

8) performing acid production treatment on the hydrothermal carbonization liquid obtained in the step 7) and the primary sewage sludge obtained in the step 4), transferring the obtained mixture to a leachate bed reactor (9) for anaerobic fermentation treatment, adding 1M NaOH to adjust the pH value of the initial reaction to 6.5-7.5, adding light fermentation degrading bacteria and methanogenic bacteria into the leachate bed reactor (9) for hydrogen production and methane production reaction, circulating the obtained hydrogen and methane in the leachate bed reactor (9) during anaerobic fermentation, and collecting the hydrogen and methane to be used as biological clean energy; the reaction time of the leachate bed reactor (9) is 12-15 days.

2. The method for producing clean energy by using kitchen waste according to claim 1, characterized in that said leachate bed reactor (9) comprises a sprayer (91) disposed at the inlet of the upper part, a filter screen (92), a solid waste holding area (93) disposed at the upper part of the filter screen (92), a filtrate collecting area (94) at the lower part of the filter screen, a first peristaltic pump (95) for circulating filtrate, a filtrate circulating pipe (96), a gas circulating pipe (97), and a second peristaltic pump (98) for circulating gas.

3. The method for producing clean energy by using kitchen waste according to claim 2, wherein the hydrothermal carbonization solution and the primary sewage sludge in the step 8) are mixed with each other, then subjected to acid production treatment and transferred to the solid waste containing area (93) of the leachate bed reactor (9), the hydrothermal carbonization solution leaks to the filtrate collecting area (94) through the filter screen (92), and then circulated to the solid waste containing area (93) through the sprayer (91), the filtrate circulating pipe (96) and the first peristaltic pump (95) to be subjected to osmotic mixing with the primary sewage sludge, and hydrogen and methane generated by anaerobic fermentation reaction are circulated in the leachate bed reactor (9) through the gas circulating pipe (97) and the second peristaltic pump (98).

4. The method for producing clean energy by utilizing the kitchen waste as claimed in claim 3, wherein the photo-fermentation degrading bacteria are added in the solid waste holding area (93), and the methanogen is added in the filtrate collecting area (94).

5. The method for producing clean energy by using kitchen waste according to claim 2, characterized in that acid production treatment is performed on the hydrothermal carbonization liquid and the primary sewage sludge in the step 8) respectively, then the hydrothermal carbonization liquid in the step 8) is transferred to the filtrate collection area (94), the primary sewage sludge is transferred to the solid waste containing area (93), the hydrothermal carbonization liquid is circulated to the solid waste containing area (93) through a sprayer (91) and is subjected to osmotic mixing with the primary sewage sludge, an anaerobic fermentation reaction occurs, and hydrogen and methane generated by the anaerobic fermentation reaction circulate in the leachate bed reactor (9) through the gas circulation pipe (97) and the second peristaltic pump (98).

6. The method for producing clean energy by utilizing the kitchen waste as claimed in claim 5, wherein the photo-fermentation degrading bacteria are added in the filtrate collecting region (94), and the methanogen is added in the solid waste containing region (93).

7. The method for producing clean energy by using kitchen waste according to any one of claims 1-6, characterized in that the acid production treatment in step 8) is adding one or more of lactobacillus, lactobacillus acidophilus, clostridium butyricum and bacillus aceticus, maintaining the temperature at 30-35 ℃, and treating for 24-36 h.

8. The method for producing clean energy by using the kitchen waste according to any one of claims 1 to 6, wherein the light fermentation degrading bacteria added in the step 8) are one or more of rhodopseudomonas, alcaligenes pseudomonad, rhodobacter capsulatus and rhodobacter sphaeroides, and the light fermentation degrading conditions are that the temperature is maintained at 29-31 ℃ and the illumination intensity is 4500-6500 lx.

9. The method for producing clean energy by using the kitchen waste according to any one of claims 1 to 6, wherein the methanogenic bacteria added in the step 8) are methanobacterium formate, methanosarcina methanolica and methanotrophic bacteria, and the condition of methane-producing anaerobic fermentation is to maintain the pH at 8-8.5 and the temperature at 30-35 ℃.

10. The method for producing clean energy by using kitchen waste according to claims 1-6, characterized in that photocatalytic nanoparticles ZnO, CdS, WO are also added into the leachate bed reactor (9)₃、SnO₂、SiC、TiO₂One or more of the photocatalytic degradation bacteria are used for enhancing the degradation efficiency of the photocatalytic degradation bacteria.