RU2413408C1 - Method of methane fermentation of manure drains - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: invention relates to the field of processing of liquid raw materials with application of biotechnological processes, namely to the field of recycling of drained wastes of vital functions of animals and birds to produce biogas as one of target products, and may be used in livestock farms and poultry farms, which mainly keep animals and birds without litter and hydraulically wash their wastes of vital functions. To realise the method, association containing cultures Corynebacterium species, Pseudomonas species, Arthrobacter simplex, which process manure into organic acids and methane-generating cultures Methanobacterium omelianskii and Methanococcus mazei, is added into manure drains with moisture from 92 to 98 wt %. Ratio of specified methane-generating cultures to manure-processing cultures makes 0.5:2 - 2:1. Titre of added cultures is from 10⁵ to 10⁸ CFU/ml. Total amount of microbial association biosuspension added into manure drain makes from 1 to 10%.

EFFECT: invention makes it possible to increase speed of biogas formation, to increase its yield, to improve content of methane in biogas.

7 cl, 4 ex

Description

The invention relates to the field of processing liquid raw materials using biotechnological processes, and in particular to the field of disposal of wastes from animals and birds to produce biogas as one of the target products, and can be used in livestock farms and poultry farms, using, preferably, bedding-free and water washing of animal and bird waste.

The widespread adoption of biogas plants is determined by the solution of two main tasks:

- disposal of organic waste (solution of environmental problems);

- receipt of warm and electric energy, ensuring the operation of the actual installation of biogas production, as well as obtaining excess heat and electric energy for sale.

For the effective operation of biogas plants, it is necessary to optimize the microbiological and technological parameters of the process, as well as the design characteristics of the bioreactors used for the specific working conditions and the raw materials used.

At the same time, a rationally organized biogas plant with an optimized method of its operation allows the processing of organic waste to produce sufficiently cheap thermal and electric energy, in particular when using animal and bird vital products as raw materials.

The environmental safety of the application and the calorific value of biogas (from 5 to 7 kcal / m ³ ), combined with the simplicity of the technology for its production, as well as the huge amount of waste to be processed - all this is a positive factor for the further development and dissemination of biogas technology in the processing of agricultural waste.

It should be noted that the processing of various organic waste by the method of anaerobic digestion with the formation of biogas has become a priority in recent years in the creation of various agricultural complexes, municipal waste disposal plants, water treatment plants, etc. Moreover, along with solving the environmental problem of waste disposal, biogas plants are used to produce cheaper electricity and heat.

Manure waste from livestock complexes along with the biotechnology of their processing into various composts, bioorganic fertilizers can be effectively used as raw materials for biogas plants.

Liquid or solid sludge formed during methanogenesis processes - waste from a working biogas plant, is transported to the fields and used as organic fertilizer. This application is due to the conditions of methanogenesis, in which pathogenic enterobacteria, enteroviruses, as well as parasitic populations almost completely die during metagenesis.

Methane digestion is a multi-stage process of microbiological processing of organic matter to final products, mainly methane and carbon dioxide. Moreover, methane-forming bacteria develop only under anaerobic conditions.

The microbiological process of methane digestion proceeds in stages: first, anaerobic microorganisms carry out enzymatic hydrolysis of the raw materials organics (proteins, lipids, polysaccharides) to low molecular weight fatty acids and alcohols, then they are oxidized by acetogenic microorganisms with the formation of low molecular weight organic acids (lactic, propionic, and other acetic acids). . In the process of enzymatic hydrolysis, hydrogen and carbon dioxide are also formed. Then, methane-forming bacteria develop using both an organic substrate and a gas mixture of hydrogen and carbon dioxide formed in the process.

In most cases, in the process of biosynthesis at the stage of methane formation, cultural associations are used. The best performance is achieved with the use of cultures such as cultures of the genus Methanobacterium, Methanococcus, etc., providing the maximum rate of methane formation at 33-37 ° C (mesophilic regime) while maintaining the optimal C: N ratio, the composition of micro- and macroelements of the mineral nutrition of cells in the fermentation medium, its mixing, pH of the medium and other process parameters.

Thermophilic cultures developing at 50-54 ° C have certain advantages, which provides an increase in the intensity (acceleration) of the process, however, this requires large expenditures of thermal energy to maintain such a high temperature in the methane heating and is not always economically justified.

In middle-climate countries, preference is given to the mesophilic fermentation mode, in which less energy is spent on maintaining the process and such thorough thermal insulation of equipment and communications is not needed.

For the production of biogas by methane digestion of liquid manure waste, the most economical installations are continuous installations that ensure a uniform output of biogas and manure. The process is optimally implemented in two reactors connected in series or in one reactor, divided into sections. In the first reactor (section), the process of anaerobic decomposition of organics occurs with the formation of acids, carbon oxides and hydrogen (acid stage). The resulting mash enters the second reactor (section), in which the process of methane formation occurs. In such a system, it is possible to independently vary the fermentation conditions (flow rate, pH, temperature) in each reactor (section), taking into account the creation of optimal conditions for the development of microorganisms of destructors in the first reactor (section) and methanogens in the second reactor (section). In general, the use of such a biosystem allows one to significantly increase the biogas yield from a plant.

The biogas yield mainly depends on the composition and type of raw materials used.

In particular, in the processing of cattle manure (cattle) in methanotine, the biogas yield, in particular, significantly depends on the composition of the manure used, determined by the animal feed formulation, the presence of plant residues in the manure, the content of organic substances and the lignocellulose complex.

The choice of conditions for the process of methane digestion and the development of the microbial community (the use of natural associations or breeding consortia of microorganisms) is an essential factor determining the biogas output, the process speed and the methane content in the gas, which ultimately determines the efficiency of the biogas plant.

Manure drains are formed on livestock farms using hydraulic or gravity-based systems for removing manure from rooms. The content of organic substances in these drains is from 1 to 2%, depending on the method of removing manure and the amount of flushing water spent on the technological needs of the farm.

Typically, such effluents are subjected to biological treatment to the norms of their discharge into open water bodies or used as fertilizer for irrigation of crops after multiple (4-10) dilution with clean water (Norms for the technological design of systems for the removal and preparation of manure for use of ONTP 17-99 of the Ministry of Agriculture of the Russian Federation) .

The disadvantages of these methods is that during biological treatment almost all organic substances are removed (the initial BOD is 10-15 g / l, and after purification - 50-150 mg / l), and a significant amount of other biogenic substances is also lost. As a result, fertilizing the fields with such drains is inefficient. In addition, biological treatment generates about 10% of excess activated sludge, which poses a danger to the environment, and it can only be used to fertilize fields after long-term storage - up to 6 months, and drying on silt sites.

It is known (Results of science and technology. Biotechnology. VINITI, Moscow, vol. 29, pp. 47-51, 1991) anaerobic digestion of manure in special digesters (anaerobic biofilters, upstream or downstream reactors, contact reactors), adapted for the fermentation of low-concentration waste. In this case, anaerobic reactors play the role of devices for preliminary treatment of manure, which also leads to a significant loss of nutrients, without which the use of manure as a fertilizer is useless. In addition, they are not disinfected from helminths and other pathogenic bacteria and are not neutralized from weed seeds.

Known (patent RU 2098933) is a method for producing organic fertilizers, including anaerobic digestion of manure. The disadvantage of this method is the impossibility of treating manure waste with a moisture content of more than 98%, as well as the impossibility of treating solid litter manure having a moisture content of less than 90%, since there is no primary stage of methane fermentation (hydrolysis) and mass transfer between methanogenic bacteria and organic substances, while there is an accumulation of excess volatile fatty acids (more than 2000 mg / l), which inhibit the process.

A known method of processing pork bedding manure into fertilizer (copyright certificate SU 950217, 1982). According to the known method, litterless pig manure, including that obtained by hydraulic washing, from the livestock building enters the manure receptacle equipped with a mixing device designed to prevent separation of incoming manure into fractions. From the specified manure collector, manure is pumped to the mixer through a pump. In the process of pumping, additional grinding of residual feed present in the manure takes place. At the same time, crushed peat, purified from foreign impurities, enters the mixer.

The peat and manure loaded into the mixer are homogenized and mixed. Then the resulting mixture is pumped into the storage tank. After filling the specified capacity, the mixture is pumped in a closed circuit, including an electro-hydraulic crusher. Upon reaching the desired uniformity of the mixture, it enters the storage of the finished product.

The disadvantage of this method should be recognized as its low nutritional value of the resulting fertilizer, due to the lack of a fermentation stage of manure, i.e. deep manure processing.

Known (patent CN 101372666) is a method of preparing organic fertilizer from manure by liquefying manure, digesting it in digesters using methane-forming bacteria to produce organic fertilizer and a small amount of biogas.

The disadvantages of this method include the low nutritional value, low quality of fertilizer due to the lack of trace elements and most organic matter, high content of pathogenic microorganisms, and low quality of the released biogas in terms of fuel methane.

Also known (patent GB 1059888) is also a method for preparing organic fertilizers by multistage anaerobic digestion of hydrocarbon feed in a digester with a mixture of crushed organic feedstock, in which, in order to accelerate the digestion process, an association of microorganism cultures, mainly processing hydrocarbons, as well as methane-forming bacteria, is used. The resulting biogas is a by-product.

An association of methane producers containing Methanosarcina majei, Methanothrix Soehugenii, Methanobacterium formicicum No. 1002 was developed for fermentation (copyright certificate SU 1104152) of plant greenhouse waste and cattle manure.

The disadvantage of the known association should be recognized as the duration of the induction period, as well as a rather small biogas yield.

A known method (copyright certificate SU 1776643) for producing biogas of fermentation of a mixture of carbohydrate raw materials and liquid manure. The moisture content in manure is up to 15%. At the first stage, a sterilizing agent is introduced into the processed mass, then a glucose-fermenting bacterium is introduced into the sterilized mass, in particular Escherichia Coli, which creates anaerobic conditions for the decomposition of glucose to produce hydrogen, carbon dioxide, acids and alcohol. Gases are separated, followed by their separation, and also acid and alcohol are separated from the fermented mass. Then, the fermented mass is re-sterilized and cellulose-destroying bacteria, in particular Clostridium thermocellum, are introduced into the sterilized mass, the formed acids and alcohol are re-separated from the fermented mass, the acids are pumped into the meta-tank, a culture of methane-forming bacteria, in particular Methanobacterium formicium, capable of generating methane and carbon dioxide is added.

The method is extremely complicated, time-consuming, methane yield is negligible.

The closest analogue of the developed technical solution can be recognized (copyright certificate SU 1049537). According to a known technical solution, a syntrophic association is known containing an acidogenic group of microorganisms, which includes Sareina maxima and Sareina ventriruli, as well as a methanogenic group, which includes Methanosareina mazei and Methanobacterium thermoantotrophicum.

The disadvantage of this method should be recognized as insufficient biogas yield for industrial use, probably due to the non-optimal selection of bacterial cultures in the proposed association.

The technical problem solved by the developed method is to optimize the process of methane digestion of manure waste.

The technical result obtained by the implementation of the developed method consists in increasing the rate of biogas formation while increasing its yield and increasing the methane content in biogas.

To increase the specified technical result, it is proposed to use the developed method of fermentation of manure waste. According to the developed method, an association containing cultures of Corynebacterium species, Pseudomonas species and Arthrobacter simplex, which process manure into organic acids, and methanogenous cultures of Methanobacterium omelianskii and Methanococcus mazei are introduced into manure effluents, the ratio of these methanogenizing to processing being 0.5 to 2 2: 1, and the total amount of moisture introduced into the manure runoff from 92 to 98 wt.% Biosuspension of microbial association with a total titer of these cultures from 10 ⁵ to 10 ⁸ (CFU / ml) is from 1 to 10 wt.%. The process is carried out under anaerobic conditions while stirring the medium in a batch or continuous mode, providing a time for fermentation of manure runoff from 7 to 15 days. It is desirable to carry out the process while maintaining the pH of the medium in the range of 6.5-7.8 and at a temperature in the range of 36.0-37.5 ° C, and large values of these parameters provide at the final stage of the process. Preferably, when sowing, the ratio of cultures of Methanobacterium omelianskii: Methanococcus mazei = 2: 1-0.5: 2, as well as the ratio of cultures of Corynebacterium species: Pseudomonas species: Arthrobacter simplex = 2: 1: 0.5-1: 1: 1, is used. Usually, a complex of microelements containing metal salts Cu, Zn, Fe, Mg, Se, Co, Cr is added to the fermented manure runoff. To increase the methane yield in the fermented manure runoff before planting or during the fermentation process, vegetable wastes pre-crushed to a particle size of 1-10 mm are added in an amount of 5 to 35 wt.% By weight of the fermented manure runoff. In particular, chopped straw, chopped tops of crops, chopped residues of plant feed of farm animals, etc. are added.

The initial manure runoff, regardless of the type of manure, contains rather small amounts of organic acids - substances processed by methane-forming bacteria to form methane, the most significant part of biogas. Therefore, in the proposed method, an association of bacteria was compiled containing microorganisms capable of utilizing the components of manure flow with the release of fatty acids, as well as methane-forming bacteria capable of utilizing the forming fatty acids to form biogas components. At the same time as the said association, the processing of manure was carried out by the microflora originally inherent in manure. Since manure runoff resulting from the life of various farm animals and birds contains different microflora inherent only to them, the process of fermentation of manure under the influence of natural microflora is not optimally aimed at obtaining biogas, i.e. biogas yield and methane content in it are not optimal.

The addition of a selected microbial association in the form of a suspension with a cell concentration of 10 ⁵ to 10 ⁸ (CFU / ml) in an amount of 1-10 wt.% To the mass of manure runoff can significantly accelerate the process of methane formation, increase the biogas yield and methane content in it.

In the course of development, an association of five types of microorganisms was compiled experimentally, the joint activity of which, when implementing the experimentally selected conditions for the methane digestion process, allows to obtain maximum biogas generation results and its optimal composition.

The following is the effect of the features introduced into the claims on the achievement of the specified technical result.

EXAMPLE 1

The laboratory process of methane fermentation was carried out using reactor flasks. The original cattle manure runoff (humidity 97.5%) was loaded into the reactor flask and hermetically closed, previously introducing a suspension of the studied microbial consortium Methanobacterium omelianskii and Methanococcus mazei, which is part of the formed association. The working volume of the flask was 700 ml, the amount of the introduced microbial suspension (inoculum) was 15 ml (2% by weight of the manure). The flask was placed in a thermostat. The thermostat was set to a temperature of 37.5 ° C, maintaining it automatically. Mixing (weak) of manure flow in the flask was carried out using a magnetic stirrer and 3 times a day with intensive shaking of the flask.

Similar process conditions were for the control flask, where the manure was fermented without adding microbial suspension due to the natural microflora of manure. It is also installed in a thermostat with the same temperature parameters.

As mentioned earlier, in the first experiment, a consortium of methanogenous cultures Methanobacterium omelianskii and Methanococcus mazei was used as a microbial association. The process was carried out in batch mode for 10 days.

When visually comparing the process, it was noted that already on the 2nd day in the experimental flask there was intense gas evolution and the volume of biogas in the volumetric flask began to increase, the process intensified especially after shaking the flask.

In the control flask (fermentation of manure with natural microflora), the process was noticeably less intense and only for 3-4 days there was an increase in the volume of biogas in the volumetric flask. The titration agent was not supplied to the flasks. Measurements of pH values: initial pH - 7.8 for a control flask pH - 7.5, for an experimental flask pH - 7.0 (the process proceeded more intensively)

As follows from the experimental data, the methanogenesis process using a consortium of microorganisms Methanobacterium omelianskii and Methanococcus mazei A-2 proceeded more intensively and ensured a higher biogas yield (84.3 mg / g dry manure in the experiment at 31.4 mg / g of dry manure under control).

So, in particular, already on the 3rd day 50 ml of biogas were released in the experimental flask, and the methane formation process almost began to appear in the control flask. On the 8th day of the experiment (the highest biogas yield), 325 ml of biogas per day were isolated in the experimental process, and only 130 ml in the control, therefore, the increase was 2.5 times. Over the 10 days of the process, 1,430 ml of biogas was released in the pilot process, and only 580 ml in the control (manure), i.e. an increase of 2.46 times. Thus, the effectiveness of the selected consortium of methane-forming bacteria relative to the natural microflora of manure is obvious.

Example 2

The experimental conditions are similar to Example 1, but as a microbial association in a 700 ml reactor flask (experiment) was added 30 ml (4% by weight of manure) of a suspension containing, in addition to methanogenic cultures of Methanobacterium omelianski, Methanococcus mazei in a ratio of 1: 1, an additional 3 crops that effectively ferment manure with the formation of organic acids and other synthesis products, namely:

Corynebacterium species - efficiently processing plant and organic substrates and used in composting,

Pseudomonas species - used in the processing of manure into fertilizer,

Arthrobacter simplex - growing on plant materials with the formation of organic acids, alcohols.

Thus, the new proposed microbial association (consortium) A-5 contains Methanobacterium omelianskii, Methanococcus mazei, as well as Corynebacterium species, Pseudomonas species and Arthrobacter simplex.

It should be noted that according to published data for the production of biogas, cultures of Corynebacterium species, Pseudomonas species, and Arthrobacter simplex were not previously used separately or together, although these cultures were previously used to obtain other target products without the participation of methane-forming bacteria.

The ratio of cultures in the association (consortium A5) was:

Methano-generating crops (Methanobacterium omelianskii, Methanococcus mazei): cultures that ferment manure to form organic acids (Corynebacterium species, Pseudomonas species, Arthrobacter simplex) = 1: 1 with an equal share of these crops (1: 1: 1).

A suspension of the indicated microbial association (consortium A5) was added to the experimental reactor flask in the amount of 30 ml per 700 ml of manure runoff containing 5.0% dry. substances and carried out the process of methane fermentation at a temperature of 37 ° C.

In a parallel (control) reactor flask, the fermentation process was carried out using the previously used association (consortium A-2) of methanogenous cultures (Methanobacterium omelianskii, Methanococcus mazei), added in an amount of 30 ml of suspension to 700 ml of the same manure runoff containing 5.0 % solids.

It was experimentally found that when fermentation of manure runoff with a moisture content of 95% (5% solids) on the third day of the experiment when using the A-5 consortium, the daily biogas output was two times higher than when using the A-2 consortium, on the seventh day, respectively one and a half times.

In just 10 days of the process, it was obtained: using a consortium (A-2) of methanogenesis cultures (Methanobacterium omelianskii, Methanococcus mazei) 3150 ml of biogas, and using a consortium (A-5) containing Methanobacterium omelianskii, Methanococcus mazei, as well as Coryne , Pseudomonas species and Arthrobacter simplex 4450 ml of biogas. This indicates a significantly greater efficiency of the A5 consortium both in terms of the rate of biogas formation and in its quantity.

The effectiveness of the association, which contains, in addition to a consortium of methane-forming bacteria, bacteria utilizing the components of manure with the formation of fatty acids, compared to using only a consortium of methane-forming bacteria, is obvious. Thus, the new association, consisting of 5 selected bacterial cultures, is much more effective.

The following experiments were carried out in larger methanotanks, comparing the effectiveness of the process with the use of the developed microbial association (A5 consortium) with the process of methane digestion with natural manure microflora.

Example 3

The methane digestion process was carried out in a pilot installation in a capacity of 50 l. The tank was filled with a manure runoff containing 5% solids at pH 7.0 and a suspension of a previously grown microorganism association (consortium A5) consisting of cultures of Methanobacterium omelianskii, Methanococcus mazei, Corynebacterium species was added to a tank of 4 dm ³ (8% by weight of manure) , Pseudomonas species, Arthrobacter simplex.

The ratio of cultures in the association (consortium A5) was:

Methano-generating crops (Methanobacterium omelianskii, Methanococcus mazei): cultures that ferment manure to form organic acids (Corynebacterium species, Pseudomonas species, Arthrobacter simplex) = 0.5: 2. Moreover, the ratio of cultures of Corynebacterium species, Pseudomonas species, Arthrobacter simplex was among themselves (2: 1: 0.5).

A complex of microelements Cu, Zn, Fe, Mg, Se, Co, Cr in the amount of 10 g was added to the manure during sowing at a ratio of these cations 10: 2: 9: 0.4: 0.6: 1.8: 1, 2. The process was carried out at a temperature of 36.5 ° C, in batch mode for 15 days with periodic manual stirring of the medium in the tank. On the 10th day of the process, a titrating agent (alkali) was added to the experimental tank for regulating the pH value, bringing the pH of the medium to the optimum value = 7.7 units. and raising the temperature in the thermostat to 37.5 ° C.

A pilot methanoten with a working volume of 50 dm ³ , which is a bottle with a cork, was placed in a thermostat (T = 36.5-37.5 ° C) and had a biogas outlet. Every day (at least 4 times a day for 15-20 minutes), vigorous shaking (mixing) of fermented manure was carried out.

The specific biogas yield in the pilot experiment was 220 dm ³ / kg of dry manure, and the methane content in biogas was 64%. In the control process (microflora fermentation of manure), the yield was 130 dm ³ / kg of dry matter of manure, and the methane content in biogas was 58%.

The high efficiency of the selected association of five cultures of bacteria relative to the natural microflora of manure is obvious.

Example 4

The methane digestion of manure runoff with a moisture content of 93% (7% dry matter) was carried out in a reactor with a working volume of 15 m ³ . The reactor filled with manure was continuously fed 0.3 m ^{3 of} manure every 6 hours (4 times a day) in a mixture with vegetable waste crushed to a size of 1-10 mm (stalk, corn stalks). The proportion of plant waste in the feed mixture ranged from 7 to 12 wt.% To the mass of manure runoff. The average estimated residence time of fermented manure in the reactor was 12.5 days. A pH of 7.5 and a temperature of 36 ° C were maintained in the reactor. Stirring was carried out using a circulation pump. Biogas was continuously taken into the gas tank, measuring the methane content in it.

An additionally grown suspension of microbial association with a cell concentration of 10 ⁷ CFU / ml in an amount of 50 dm ³ (3% by weight of the manure in the apparatus) was additionally introduced into the manure runoff. The association (consortium A5) consisted of cultures of Methanobacterium omelianskii, Methanococcus mazei, Corynebacterium species, Pseudomonas species, Arthrobacter simplex.

The ratio of cultures in the association (consortium) was:

Methano-generating crops (Methanobacterium omelianskii, Methanococcus mazei): cultures that ferment manure to form organic acids (Corynebacterium species, Pseudomonas species Arthrobacter simplex) = 2: 1. Moreover, the ratio of cultures of Corynebacterium species, Pseudomonas species, Arthrobacter simplex was among themselves (1: 1: 1).

After reaching a stable mode (after 2 weeks), the daily volume of biogas formed in the process was:

300-320 m ³ / day of biogas, and methane yield - an average of 200 m ³ / day.

When carrying out the continuous digestion process on a similar manure runoff without adding a suspension of the indicated microbial association, the process stabilized only after 3 weeks and the daily volume was 120-150 m ³ biogas per day with a methane content of 55-57%.

During the implementation of the development of the method, no effect was found on the achievement of the technical result of specific strains of these crops, as well as the type of manure - pork, poultry or cattle.

Although the association of microorganisms used, as well as the closest analogue, contains two groups of bacteria: acid-generating and methane-generating, the types of bacteria used in the proposed association, their ratio, and process parameters made it possible to increase the biogas yield with an increased methane content in it.

These examples do not limit the proposed method.

Claims (7)

1. The method of methane digestion of manure wastes, characterized in that an association containing cultures of Corynebacterium species, Pseudomonas species, Arthrobacter simplex, which process manure into organic acids, and methane-generating cultures of Methanobacterium omelianskii and Methanococcus mazei are introduced into the manure waste, moreover: manure-processing crops ranges from 0.5: 2 to 2: 1, and the total amount of moisture introduced into the manure runoff from 92 to 98 wt.% biosuspension of microbial association with a total titer of these crops from 10 ⁵ to 10 ⁸ CFU / ml was is from 1 to 10 wt.%. 2. The method according to claim 1, characterized in that the process is carried out with stirring the medium in a batch or continuous mode, providing a time for fermentation of manure flow from 7 to 15 days. 3. The method according to claim 1, characterized in that the process is carried out while maintaining the pH of the medium in the range of 6.5-7.8, at a temperature in the range of 36.0-37.5 ° C, and large values of these parameters are provided at the final process steps. 4. The method according to claim 1, characterized in that when sowing use the ratio of cultures of Methanobacterium omelianskii: Methanococcus mazei, equal to 2: 1-0.5: 2. 5. The method according to claim 1, characterized in that when sowing use the ratio of cultures of Corynebacterium species: Pseudomonas species: Arthrobacter simplex, equal to 2: 1: 0.5-1: 1: 1. 6. The method according to claim 1, characterized in that a microelement complex containing metal salts of Cu, Zn, Fe, Mg, Se, Co, Cr is added to the fermented manure runoff. 7. The method according to claim 1, characterized in that vegetable waste is preliminarily crushed to a particle size of 1-10 mm in an amount of 5 to 35 wt.% By weight of the fermented manure runoff added to the fermented manure runoff.