1. The household garbage treatment process is characterized by comprising the following steps: sorting, crushing and screening, washing pulp by water power and anaerobic fermentation;

wherein the anaerobic fermentation system is added with a trace element additive, and the mass ratio of the trace element additive to a fermentation substrate prepared by hydraulic pulp washing is 1: (9000-11000), the metal elements in the trace element additive comprise Fe, Ni, Co, Mo, Se and W.

2. The domestic waste treatment process according to claim 1, wherein: the trace element additive comprises the following ions in parts by weight: fe²⁺8-16 parts of Ni²⁺2-6 parts of Co²⁺4-8 parts of Mo⁶⁺3-7 parts of Se⁴⁺1-3 parts of W⁶⁺0.5-3 parts.

3. The domestic waste treatment process according to claim 2, wherein: the trace element additive comprises the following ions in parts by weight: fe²⁺10 to 14 portions of Ni²⁺3-5 parts of Co²⁺5-7 parts of Mo⁶⁺4-6 parts of Se⁴⁺1.5-2.5 parts of W⁶⁺1-2 parts.

4. The domestic waste treatment process according to claim 2, wherein: the trace element additive also comprises nitrilotriacetic acid, nitrilotriacetic acid and Ni²⁺The weight ratio of (1-2): 1.

5. the domestic waste treatment process according to claim 2, wherein: the microelement additive also comprises EDTA, EDTA and Co²⁺The weight ratio of (1-2): 1.

6. the domestic waste treatment process according to claim 1, wherein: the treatment process also comprises hydrothermal pretreatment, wherein the hydrothermal pretreatment step is arranged after the hydraulic pulp washing and before the anaerobic fermentation;

the hydrothermal pretreatment method comprises the following steps: keeping the prepared fermentation substrate after hydraulic pulp washing and a sodium hydroxide solution with the volume percentage concentration of 1-3% for 30-40min at the temperature of 210 ℃ and 230 ℃, wherein the weight ratio of the fermentation substrate to the sodium hydroxide solution is 1: (20-30).

7. The domestic waste treatment process according to claim 1, wherein: the particle size of the crushed solid particles of the domestic garbage is 15-80 mm.

8. The domestic waste treatment process according to claim 1, wherein: the reaction temperature of the anaerobic fermentation is 30-35 ℃.

Background

The household garbage is garbage generated in the daily life process of residents, the kitchen garbage accounts for a large proportion, and the kitchen garbage mainly comprises kitchen garbage and food and beverage garbage, such as leftovers, bones, eggshells and the like. Most of the kitchen contains abundant organic matters and water, is very easy to rot and emit odor, is easy to breed mosquitoes and flies, influences the living environment of people and influences ecological health. Therefore, the domestic waste must be well treated.

The traditional domestic garbage treatment methods comprise the following steps: landfill, aerobic composting and anaerobic fermentation, wherein the landfill and the composting can invade the land and cause certain pollution to the land. Anaerobic fermentation is a process of converting organic matters in the domestic garbage into methane under the synergistic action of anaerobic microorganism methanogens at a certain temperature under an anaerobic condition.

The inventors found that in the actual anaerobic fermentation process, the fermentation efficiency was low and the methane yield was low.

Disclosure of Invention

In order to improve the methane yield of anaerobic fermentation, the application provides a domestic garbage treatment process.

In a first aspect, the present application provides a domestic waste treatment process, which adopts the following technical scheme:

a household garbage treatment process comprises the following steps: sorting, crushing and screening, washing pulp by water power and anaerobic fermentation;

wherein the anaerobic fermentation system is added with a trace element additive, and the mass ratio of the trace element additive to a fermentation substrate prepared by hydraulic pulp washing is 1: (9000-11000), the metal elements in the trace element additive comprise Fe, Ni, Co, Mo, Se and W.

By adopting the technical scheme, trace elements are supplemented in the fermentation process, and Fe, Ni, Co, Mo, Se and W can promote the synthesis of different enzymes and improve the metabolic activity of microorganisms, thereby promoting the fermentation of substrates and improving the yield of methane. The supplement of Fe promotes the generation of volatile fatty acid and improves the utilization rate of methanogens to acetic acid, and Ni can effectively promote the degradation of volatile acid in the fermentation process and improve the yield of methane; co maintains the normal metabolism of microorganisms, Mo can promote the degradation of acetic acid and propionic acid, can also inhibit the metabolism of sulfate reducing bacteria and promote the metabolism of methanogens, and Se and W have synergistic effect and can promote the growth of the methanogensActivating the activity of enzyme, enriching the diversity of methanogens and improving CO₂Efficiency of conversion to methane. The microorganisms and enzymes in the whole anaerobic fermentation system are various, and the requirement is not only a single element but also the synergistic action of a plurality of elements.

Preferably, the trace element additive comprises the following ions in parts by weight: fe²⁺8-16 parts of Ni²⁺2-6 parts of Co²⁺4-8 parts of Mo⁶⁺3-7 parts of Se⁴⁺1-3 parts of W⁶⁺0.5-3 parts.

By adopting the technical scheme, the addition amount of each trace element is controlled, so that the trace elements can be matched with each other, the promotion effect of the trace elements on microbial metabolism in a fermentation system and the synthesis of enzyme are exerted, the fermentation of a substrate is further promoted, and the yield of methane is improved.

Preferably, the trace element additive comprises the following ions in parts by weight: fe²⁺10 to 14 portions of Ni²⁺3-5 parts of Co²⁺5-7 parts of Mo⁶⁺4-6 parts of Se⁴⁺1.5-2.5 parts of W⁶⁺1-2 parts.

By adopting the technical scheme, the proportioning relation among the trace elements is further optimized, the fermentation of the substrate is further promoted, and the yield of methane is improved.

Preferably, the trace element additive further comprises nitrilotriacetic acid, nitrilotriacetic acid and Ni²⁺The weight ratio of (1-2): 1.

by adopting the technical scheme, Ni²⁺Before being absorbed and utilized by microorganisms, the Ni can generate complex chemical reactions such as complexation, precipitation and the like with organic matters, ions and the like, thereby reducing Ni²⁺The bioavailability of (A) is improved by adding nitrilotriacetic acid and Ni²⁺By chelating, Ni can be increased²⁺The bioavailability of the compound is improved, and the yield of methane is improved.

Preferably, the trace element additive further comprises EDTA, EDTA and Co²⁺The weight ratio of (1-2): 1.

by adopting the technical scheme, in an anaerobic environment, Co is precipitated by sulfide to cause extremely low dissolution concentration and mainly appears in a strong complex form, but the non-free Co can not be utilized by methanogens, and EDTA and Co are added for chelation, so that the biological effectiveness of Co can be improved, and further the methane yield is improved.

Preferably, the treatment process further comprises hydrothermal pretreatment, wherein the hydrothermal pretreatment step is arranged after the hydraulic pulp washing and before the anaerobic fermentation;

the hydrothermal pretreatment method comprises the following steps: keeping the prepared fermentation substrate after hydraulic pulp washing and a sodium hydroxide solution with the volume percentage concentration of 1-3% for 30-40min at the temperature of 210 ℃ and 230 ℃, wherein the weight ratio of the fermentation substrate to the sodium hydroxide solution is 1: (20-30).

By adopting the technical scheme, the fermentation substrate can contain degraded grease, the methanogen and the like are coated, the normal metabolic activity of the methanogen is influenced, the macromolecular grease is degraded into micromolecules by hydrothermal treatment, the coating of the methanogen is reduced, the utilization difficulty of the methanogen to the substrate is reduced, and the methane yield is improved.

Preferably, the particle size of the solid particles of the crushed domestic garbage is 15-80 mm.

By adopting the technical scheme, the fermentation substrate in the particle size range is easier to be utilized by methanogens for metabolism, the substrate fermentation is promoted, and the methane yield is improved.

Preferably, the reaction temperature of the anaerobic fermentation is 30-35 ℃.

By adopting the technical scheme, the medium-temperature fermentation is carried out, the utilization of the methanogen to the substrate is facilitated, and the methane yield is improved.

In summary, the present application has the following beneficial effects:

1. as the method supplements Fe, Ni, Co, Mo, Se and W in the anaerobic fermentation process, improves the metabolic activity of methanogens, promotes the fermentation of the substrate, and the methane yield reaches 865.4-882.3ml g-¹The yield of methane is effectively improved;

2. in the present application, it is preferred to use a heat of hydration treatment of the fermentation substrate with a methane yield of 880.1-882.3 ml-g-¹Further improving the yield of methane.

Detailed Description

Anaerobic fermentation is through anaerobic microorganism metabolism, decomposes fermentation substrate, carries out metabolic fermentation through methanogen in the domestic waste anaerobic fermentation, contains relevant metabolic enzyme in the methanogen, along with the going on of fermentation, because microelement's lack, the metabolic activity of methanogen reduces, influences fermentation efficiency, promotes the metabolic activity of methanogen through replenishing microelement in the fermentation process in this application to improve methane yield. The present application will be described in further detail with reference to examples.

Preparation examples of starting materials and intermediates

Raw materials

Fe²⁺With FeSO₄·7H₂Adding in the form of O;

Ni²⁺with NiCl₂·6H₂Adding in the form of O;

Co²⁺with CoCl₂·6H₂Adding in the form of O;

Mo⁶⁺with Na₂MoO₄·2H₂Adding in the form of O;

Se⁴⁺with Na₂SeO₃Is added in the form of (1);

W⁶⁺with Na₂WO₄Addition in the form of 2H 2O;

nitrilotriacetic acid, available from Shanghai Hope trading Limited;

EDTA, available from Lishui Bordetella chemical Co., Ltd.

Preparation example

Preparation example 1

The preparation method of the microelement additive comprises the following steps:

f is to be²⁺FeSO with a content of 8g₄·7H₂O、Ni²⁺NiCl with a content of 6g₂·6H₂O、Co²⁺CoCl with a content of 4g₂·6H₂O、Mo⁶⁺Na content of 7g₂MoO₄·2H₂O、Se⁴⁺Na content of 1g₂SeO₃、W⁶⁺Na content of 3g₂WO₄2H2O, and mixing uniformly to obtain the microelement additive.

Preparation examples 2 to 5

Different from the preparation example 1, the raw materials have different proportions and are detailed in the table 1.

Preparation example 6

Different from preparation example 3, 4g of nitrilotriacetic acid was also contained in the trace element additive, and in the preparation of the trace element additive, nitrilotriacetic acid and NiCl were added₂·6H₂Mixing with other raw materials.

Preparation examples 7 to 8

The differences in the amounts of nitrilotriacetic acid added, in comparison with preparation example 6, are shown in Table 1.

Preparation example 9

Different from preparation example 7, the trace element additive further contained 6g of EDTA, and when the trace element additive was prepared, EDTA and CoCl were added₂·6H₂Mixing with other raw materials.

Preparation examples 10 to 11

Different from preparation example 6, the amount of EDTA added is shown in Table 1.

TABLE 1 preparation examples 1-11 raw material compounding ratio (g)

	Fe2+	Ni2+	Co2+	Mo6+	Se4+	W6+	Nitrilotriacetic acid	EDTA
									Preparation example 1	8	6	4	7	1	3	0	0
Preparation example 2	10	5	5	6	1.5	2	0	0
									Preparation example 3	12	4	6	5	2	1.5	0	0
Preparation example 4	14	3	7	4	2.5	1	0	0
									Preparation example 5	16	2	8	3	3	0.5	0	0
Preparation example 6	12	4	6	5	2	1.5	4	0
									Preparation example 7	12	4	6	5	2	1.5	6	0
Preparation example 8	12	4	6	5	2	1.5	8	0
									Preparation example 9	12	4	6	5	2	1.5	6	6
Preparation example 10	12	4	6	5	2	1.5	6	9
									Preparation example 11	12	4	6	5	2	1.5	6	12

Examples

Example 1

A household garbage treatment process comprises the following steps:

s1, sorting: carrying out solid-liquid separation on the household garbage, and conveying the liquid to a set place for sewage treatment;

s2, crushing and screening: conveying the solids separated in the S1 to a crusher for coarse crushing, carrying out magnetic separation on the particles obtained after coarse crushing to remove magnetic impurities, conveying the particles to a bag-breaking drum sieve, and reserving the particles with the particle size of 15-80 mm; continuously crushing the particles with the particle size of more than 80mm, and performing landfill treatment on the particles with the particle size of less than 15 mm;

s3, winnowing: removing plastic, paper and other substances in the granules screened by the bag-breaking drum screen by using a winnowing method;

s4, hydraulic pulp washing: carrying out hydraulic pulp washing on solid particles left after air separation; according to the difference of specific gravity of the materials, heavy materials such as dregs and the like sink into the lower part, light materials such as plastics and the like float on the upper part, the sunk materials can be sent to a brick making process, the floated materials enter a recovery system, and the middle materials are fermented;

s5, anaerobic fermentation: introducing the middle substance of the hydraulic pulp washing in the S4 into a fermentation tank, weighing the middle substance by a weighing system before the middle substance enters the fermentation tank, adding methanogens and the trace element additive from the preparation example 1 into the fermentation tank at a weight ratio of 1:9000, introducing nitrogen into the fermentation tank to manufacture an anaerobic environment, and heating the fermentation tank to ensure that the temperature in the fermentation tank is 30 ℃;

and S6, storing the biogas generated by anaerobic fermentation after desulfurization, freezing and drying.

Examples 2 to 3

Different from the example 1, the weight ratio of the trace element additive to the middle substance in the step S5 is 1:10000 and 1:11000, respectively.

Examples 4 to 13

In contrast to example 2, the trace element additives were obtained from preparation examples 2 to 11, respectively.

Example 14

In contrast to example 12, particles having a particle size of more than 80mm were retained in S2.

Example 15

Unlike example 12, particles having a particle size of less than 15mm were retained in S2.

Examples 16 to 19

Unlike example 12, the fermentation temperature in S3 was 32.5 ℃, 35 ℃, 25 ℃ and 40 ℃.

Example 20

A household garbage treatment process comprises the following steps:

s1, sorting: carrying out solid-liquid separation on the household garbage, and conveying the liquid to a set place for sewage treatment;

s2, crushing and screening: conveying the solids separated in the S1 to a crusher for coarse crushing, carrying out magnetic separation on the particles obtained after coarse crushing to remove magnetic impurities, conveying the particles to a bag-breaking drum sieve, and reserving the particles with the particle size of 15-80 mm; continuously crushing the particles with the particle size of more than 80mm, and performing landfill treatment on the particles with the particle size of less than 15 mm;

s3, winnowing: removing plastic, paper and other substances in the granules screened by the bag-breaking drum screen by using a winnowing method;

s4, hydraulic pulp washing: carrying out hydraulic pulp washing on solid particles left after air separation; according to the difference of specific gravity of the materials, heavy materials such as dregs and the like sink into the lower part, light materials such as plastics and the like float on the upper part, the sunk materials can be sent to a brick making process, the floated materials enter a recovery system, and the middle materials are fermented;

s5, hydrothermal pretreatment: keeping the prepared fermentation substrate after hydraulic pulp washing and a sodium hydroxide solution with the volume percentage concentration of 1% for 40min at the temperature of 210 ℃, wherein the weight ratio of the fermentation substrate to the sodium hydroxide solution is 1: 20.

s6, anaerobic fermentation: introducing the middle substance of the hydraulic pulp washing in the S4 into a fermentation tank, weighing the middle substance by a weighing system before the middle substance enters the fermentation tank, then adding methanogens and the trace element additive from the preparation example 1 into the fermentation tank, wherein the weight ratio of the trace element additive to the middle substance is 1:9000, introducing nitrogen into the fermentation tank to manufacture an anaerobic environment, and heating the fermentation tank to ensure that the temperature in the fermentation tank is 32.5 ℃;

and S7, storing the biogas generated by anaerobic fermentation after desulfurization, freezing and drying.

Examples 21 to 22

Unlike example 20, the sodium hydroxide solution in S5 was at 2% and 3% by volume, respectively.

Example 23

Unlike example 21, the reaction temperature in S5 was 220 ℃ and the reaction time was 35 min.

Example 24

Unlike example 21, the reaction temperature in S5 was 230 ℃ and the reaction time was 30 min.

Examples 25 to 26

In contrast to example 23, the weight ratio of fermentation substrate to sodium hydroxide solution in S5 was 1: 25. 1: 30.

comparative example

Comparative example 1

Unlike example 1, no trace element additive was added.

Comparative example 2

Unlike example 1, the metal element in the trace element additive did not include Fe.

Comparative example 3

Unlike example 1, the metal element in the trace element additive did not include Ni.

Comparative example 4

Unlike example 1, the metal element in the trace element additive does not include Co.

Comparative example 5

Unlike example 1, the metal element in the trace element additive did not include Mo.

Comparative example 6

Unlike example 1, the metal element in the trace element additive does not include Se.

Comparative example 7

Unlike example 1, the metal element in the trace element additive does not include W.

Performance test

Test method

The mass of the middle material of the hydropulp entering the fermentor was controlled to be the same and the methane yield and methane production rate were determined in examples 1-23 and comparative examples 1-7.

Determination of methane yield: measuring the total amount of stored fermentation gas after 48d of fermentation, recording the total amount as A (ml), taking a certain amount of gas generated by anaerobic fermentation as experimental gas, recording the total amount as a (ml), and measuring the content of methane in the experimental gas by using a gas chromatograph, recording the content as k (ml); the methane production is a (k/a) and the methane yield is the ratio of methane production to fermentation substrate mass.

Determination of the methanogenesis rate: the methane production rate, methane yield/fermentation time, was measured daily and the highest rate and the time to reach the highest rate were recorded.

TABLE 2 Performance test results

As can be seen by combining examples 1-26 and comparative examples 1-7, and by combining Table 2, the peak values of the yield of methane and the methane production rate in the domestic waste treatment processes of examples 1-26 are higher than those in comparative examples 1-7, which indicates that the domestic waste treatment process of the present application has an effect of promoting substrate fermentation, and can improve the yield of methane.

As can be seen by combining examples 1-7 with Table 2, the yield of methane and the peak value of the methane production rate in example 5 are relatively high, indicating that the trace element additive obtained in preparation example 3 is superior in effect.

By combining the example 1 and the comparative examples 1-5 and combining the table 2, it can be seen that the methane yield can be effectively improved by adding the trace elements into the anaerobic fermentation system, and the mutual matching of Fe, Ni, Co, Mo, Se and W in the trace elements has a more obvious promoting effect on the fermentation of the substrate, thereby being more beneficial to improving the methane yield.

Combining example 5 with examples 8-10, and Table 2, it can be seen that the methane yield was higher in examples 8-10 than in example 5, and the peak in methane production rate was higher in examples 8-10 than in example 3, and the time to reach the peak in methane production rate was also shorter, perhaps by increasing the Ni content with the addition of nitrilotriacetic acid²⁺Thereby enhancing the bioavailability of Ni²⁺Promoting fermentation.

Combining example 9 with examples 11-13 and Table 2, it can be seen that the methane yield was higher in examples 11-13 than in example 9, and the peak in methane production rate was higher in examples 11-13 than in example 9, and the time to reach the peak in methane production rate was also shorter, probably by adding EDTA to increase the Co yield²⁺Thereby enhancing the bioavailability of Co²⁺Promoting fermentation.

Combining example 12 with examples 14-15, and table 2, it can be seen that the methane yield in example 12 is higher than in examples 14-15, probably because breaking up particles with a particle size of 15-80mm is more suitable for fermentation, thereby increasing the methane yield.

In combination with examples 12 and 16 to 19 and Table 2, it can be seen that the fermentation temperature has a certain influence on the methane yield, and that the fermentation temperature is preferably from 30 ℃ to 35 ℃.

Combining example 16 with examples 20-22, and table 2, it can be seen that the methane yield in examples 20-22 is significantly higher than in example 16, indicating that hydrothermal treatment of the fermentation substrate prior to anaerobic fermentation can increase the methane yield, probably because the hydrothermal treatment degrades the macromolecular ferment into a relatively small molecular ferment, reducing the difficulty of substrate utilization by the flora, and increasing the methane yield.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.