Installation for biogas production (cheap do-it-yourself gas). Methods for self-production of biogas Installation for producing biogas u3

05.09.2023

Features of organic waste processing in home bio-installations. Processing organic waste without access to oxygen is a highly effective way to obtain high-quality organic fertilizers and an environmentally friendly energy carrier, which is biogas. Moreover, this method of waste processing is absolutely safe for the environment.

Biogas is a gas that is approximately 60% methane and 40% carbon dioxide (CO2). A variety of microbial species metabolize carbon from organic substrates under oxygen-free (anaerobic) conditions (Table 4).

Biogas yield (m3) from one ton of organic matter
Type of organic raw materials	Gas output, m3 per ton of raw material
Cattle manure
Pig manure
Bird droppings
Horse dung
Sheep manure
Corn silage
Grass silage
Fresh grass

Sugar beet leaves
Ensiled sugar beet leaves

This is the process of so-called putrefaction or oxygen-free fermentation.

Methane fermentation is a complex anaerobic process (without air access), which occurs as a result of the vital activity of microorganisms and is accompanied by a number of biochemical reactions. The fermentation temperature is 35°C (mesophilic process) or 50°C (thermophilic process). This method should be assessed as a local environmental protection measure, which at the same time improves the energy balance of the economy, since it is possible to organize a low-waste, energy-saving economy.

During the processing of liquid manure with a moisture content of up to 90-91% in a methane digestion unit, three primary products are obtained: dewatered sludge, biogas, and liquid waste. Dehydrated sludge is odorless, does not contain pathogenic microflora, and the germination of weed seeds is reduced to zero. In general, dewatered sludge is a highly concentrated, disinfected, deodorized organic fertilizer suitable for direct application to the soil. It is also used as a raw material for the production of vermicompost. Methane fermentation improves the quality of the substrate. This occurs due to the fact that during methane fermentation without access to oxygen, ammonia nitrogen is converted into ammonium form, which subsequently, in the process of aerobic fermentation, reduces nitrogen losses. The substrate obtained from fermented manure and litter helps increase crop yields by 15-40%.

Since 1920, biogas has been produced on a large scale from sewage wastewater. In European cities, city truck fleets began to be converted to run on biogas in 1937. During World War II and the post-war era, the production of biogas from organic waste was researched and promoted. Due to the decline in oil prices, the development of biogas technologies ceased in the 60s. In developing countries, simple biogas plants have become widespread. Millions of such “backyard” type installations have already been created in China. About 70 million units have been built in India. In developed countries, after the 1973 crisis, large-volume biogas plants became widespread. It has become possible to quickly ferment sewage in anaerobic filters at a relatively low fermentation temperature.

Among the variety of biogas plants that operate today in many countries around the world, there are plants with reactor volumes from several to several thousand cubic meters. Conventionally, they can be divided into:

Small, or household - reactor volume up to 20 m3;

Farm - 20-200 m3;

Medium - 200-500 m3;

Large - over 500 m3

Advantages of biogas plants:

Agronomic - the ability to obtain highly effective organic fertilizers;

Energy - biogas production;

Environmental - neutralization of the negative impact of waste on the environment;

Social - improving living conditions, which is especially important for residents of rural areas.

Many countries are widely using the potential that this method of waste processing provides. Unfortunately, in Ukraine even now it remains somewhat exotic and is used in practice in isolated cases, in particular for the anaerobic processing of organic waste for fertilizer, which is relevant in the current conditions. Even the energy crisis did not stimulate the development of this energy production technology, while in some countries, such as India and China, national programs for recycling waste in bio-based plants have been operating for a long time. A significant percentage of the energy needs in many European countries are provided by this technology, and in England, even before 1990, it was planned to provide the rural population with gas of “own production.”

Figure 41. Biogas plantFigure 42.Indian

biogas plant in Ethiopia

Without discounting the importance of large-scale plants, it is worth paying close attention to the advantages of small biogas plants. They are cheap, available for construction by individual and industrial methods, simple and safe to maintain, and the products of organic waste processing in them - biogas and high-quality organic fertilizers - can be used directly for the needs of the farm without the cost of transportation.

The advantages of small biogas plants include the availability of local materials for the construction of the plant, the possibility of maintenance by the owner, the absence of the need for accounting, transportation over long distances and preparation for the use of biogas.

Small biogas plants also have certain disadvantages compared to large ones. Here it is more difficult to automate and mechanize the processes of preparing the substrate and the operation of the installations themselves; grinding the substrate, its heating, loading and unloading, storage before and after processing, which predetermines the need for containers for storing fermented waste, is problematic. In addition, in order to bring the substrate to the concentration required for fermentation, you should have another container and a certain amount of water. To reduce water costs, it is worth considering the possibility of its reuse. Problems also arise with dehydration of the fermented mass. Most often, units that are used for mechanization of work (grinding, mixing, heating, feeding processed products, etc.) in large installations are unsuitable for use in small ones due to their technical parameters and high cost.

Homestead plants produce small volumes of biogas, so it is more difficult to organize the processes of its dehydration and purification from impurities of non-combustible components.

The problems of operating small biogas plants include the unevenness of the process of producing biogas at different times of the year. During the summer period of operation, problems arise due to the fact that in the presence of a gas heater, less biogas of own production will be spent on heating the substrate; its commercial quantity will be greater than in the winter. In the summer, when animals are turned out to pasture, the amount of waste, the raw material for the bioreactor, decreases. As part of such installations, it is inappropriate to provide units for significant accumulation of biogas - when more gas is produced than is needed for the economy, it will simply have to be released into the atmosphere.

But no matter what, anaerobic processing of organic waste is a highly effective and profitable way to obtain high-quality organic fertilizers and environmentally friendly energy carriers. Small household biogas-humus plants with a reactor of up to 20 m3 can be recommended for installation in almost every rural yard where organic waste accumulates.

Among the main modern trends in the development of biogas technologies are the following:

Fermentation of multicomponent substrates;

The use of “dry” type of anaerobic fermentation for the production of biogas from energy plant crops;

Creation of centralized biogas stations with high productivity and the like.

There are four main types of implementation of anaerobic digestion technology, namely: covered lagoons and digesters operating in the mode of a mixing reactor and a reactor with a biomass carrier. The technical and economic feasibility of using one type or another depends mainly on the moisture content of the substrates and climatic conditions in the area where the biogas plant is located. The type of bioreactor used affects the total duration of the methanization process.

Indoor lagoons are advisable to use in warm and temperate climates - for liquid manure waste that does not contain inclusions with significant hydraulic coarseness. Such reactors are not specially heated, and therefore they are considered not intensive. The duration of decay of organic matter to stabilize waste significantly exceeds that in reactors with intensive fermentation mode.

Reactors with intensive fermentation mode include heated reactors of various types. There are two fundamental differences between the designs of such reactors, which depend on the characteristics of the fermented substrates. In reactors of the first type, substrates with a predominance of liquid manure waste are fermented. The most common type of such reactors are cylindrical concrete or steel with a central column, covered with an elastic membrane, which serves to seal the structure and accumulate the generated biogas. Such reactors operate on the principle of complete mixing, when each fresh portion of the mixture of initial substrates is mixed with the entire fermentable mass of the reactor. The basic design of such reactors is shown in Figure 43.

Fig.43 . Vertical type digester

2 - substrate overflow;

3 - air supply pump;

4 - thermal insulation of the methane tank;

5 - central column, which supports the gas tank membrane from falling;

6 - mixing device;

7 - drive of the mixing device;

8 - service area;

9 - gas tank membrane;

10 - methane tank filling level;

11 - height of raising of the gas tank membrane;

12 - heating pipelines

Another type of reactor for liquid substrates is the horizontal type, operating on the displacement principle. In such structures, the initial substrate mixture is supplied from one side and removed from the other. In this case, organic matter undergoes successive transformations due to a consortium of microorganisms already present in the original substrate. Such reactors can be considered less efficient in terms of the intensity of the process, however, in them, due to the spatial separation of the entry points of fresh substrates and the exit points of fermented ones, it is possible to minimize the risk of the release of an unfermented portion of fresh substrates along with the fermented substrate (which is removed from the methane tank). It is advisable to use reactors of this type for small volumes of fermented substrates.

The following type of reactors are designed for the methanization of dry organic mixtures, in which cosubstrates from energy plant crops predominate. Reactors of this type are becoming widespread along with the spread of technologies for “dry” fermentation of energy plant crops. A characteristic feature of such methane tanks is that they are designed as full displacement reactors.

From a technological point of view, the process of producing biogas from organic matter is multi-stage. It consists of the process of preparing substrates for fermentation, the process of biological decomposition of the substance, post-fermentation (optional), processing of the fermented substrate and extracted biogas, preparing them for use or disposal on site. Figure 2 shows a schematic flow diagram of a typical farm biogas station for co-digestion of manure waste and organic co-substrates.

Rice. 44. Schematic diagram of a typical farm biogas station

Preparing the substrate for fermentation involves collecting and homogenizing (mixing) the substrate. To collect the substrate, depending on its design quantity, a storage tank is built, equipped with a special mixing device and a pump, which will subsequently supply the prepared substrate to the reactor (methane tank). Depending on the types of substrates, the substance preparation system can be complicated by modules for grinding or sterilizing cosubstrates (if necessary).

After preliminary preparation, a pre-calculated amount of substrate is pumped using pumps through a pipeline system to the reactor. In a reactor (methane tank), the substrate is subject to destruction with the participation of microbiocenosis over a calculated period of time, depending on the selected temperature regime. The digester tank is equipped with a system of heating pipelines, a mixing device (to eliminate the possibility of stratification of the medium and the formation of a crust, uniform division of substances nutritious for the microbiological environment and leveling the temperature of the substrate), systems for removing the extracted biogas and discharging the fermented substrate. In addition, the digester tank is equipped with an air supply system, a small amount of which is needed to purify biogas from hydrogen sulfide by biochemical precipitation.

The degree of decomposition of organic matter at the time of completion of active gas formation approaches 70-80%. In this state, the fermented organic mass can be fed to a separation system to be divided into solid and liquid parts in a special separator.

There are several schemes for utilization of extracted biogas, the main one of which is the combustion of biogas in a cogeneration plant directly on site, with the production of electricity and heat, which are used for the own needs of the farm and the biogas station. In addition, part of the electrical energy is transmitted to the power grid.

The main substrate for anaerobic digestion, as a rule, is animal and poultry manure, as well as slaughterhouse waste. Substrates of this origin contain the most microorganisms necessary for the organization and progress of the methane fermentation process, since they are already present in the stomach of animals.

As the experience of Germany shows, most installations operate on a mixture of cosubstrates with different proportions. The country implemented a special program to collect data from more than 60 representative operating biogas plants and analyzed them. There are quite a lot of stations (about 45%), where manure is used as the main substrate in a volume of 75-100% of the total volume of the mixture. However, there are also many stations where the slurry content is less than 50%. This indicates that biogas plants in Germany largely utilize the potential not only of manure waste, but also of a variety of additional co-substrates when producing biogas.

Analysis of data on biogas production at these stations showed that with an increase in cosubstrate particles in the mixture, the specific yield of methane increases. The most common type of cosubstrate is corn silage. It is purchased from farmers in crushed form, ready for loading into reactors, and stored in open fenced areas. In addition to corn silage, grass silage, grain chaff, fat waste, grass clippings, whey, food and vegetable waste, and the like are also widely used.

In the minds of the Ukrainian farmer, a biogas plant is strongly associated exclusively with the processing of waste from large farms. The main incentive for the construction of biogas plants in Ukraine, which is often not very effective, remains the need for wastewater treatment. The possibility of obtaining high-quality organic fertilizers is also interesting for the farmer. The energy aspects of biogas production remain underutilized due to low tariffs for electricity and heat, resulting in very low return on investment for biogas plants through energy sales.

Of course, in order for biogas technologies to begin to actively develop, it is necessary to legalize the system of “green” tariffs for all types of renewable electrical and thermal energy, as has already happened in many countries of the world, and not only in developed ones.

Another way to increase the efficiency of biogas plants is to actively use additional substrates for fermentation, such as corn silage. An excellent example of an effective biogas plant is the BGU of the German company Envitek Biogas. The company's standard BGU is equipped with a 2500 m3 reactor and a cogeneration unit with an electrical power of 500 kW. The basic supplier of raw materials for such an installation could be a typical German pig farm with a population of 5,000 pigs. An increase in biogas yield is achieved by adding corn silage. For continuous operation of the installation throughout the year, 6000 tons of silage are needed, or 300 hectares of land with a silage yield of 20 t/ha.

Brief technical characteristics of biogas company LLC				Biodieseldnepr"
Installation brand	Reactor volume, m 3	Installed power	Biogas output	Electricity production, kW	Production heat, kW	Biogasoline

Liquid waste is a disinfected, deodorized liquid that contains up to 1% of suspended substances and contains fertilizing elements. Centrate is an excellent organic feed for agricultural crops, the use of which is convenient both for watering and irrigation. After post-treatment, liquid waste can even be used as process water.

Biogas is used to produce electrical and thermal energy. By burning 1 m3 of biogas, you can get 2.5-3 kW/hour of electricity and 4-5 kW of thermal energy. At the same time, 40-60% of biogas is used for the technological needs of the installation. Biogas under pressure 200-220 atm. can be used to refuel vehicles.

In addition to producing energy and fertilizers during waste fermentation, biogas plants act as treatment facilities - they reduce chemical and bacteriological pollution of soil, water, air and convert organic waste into neutral mineralized products. Compared to the energy of small rivers, wind and solar energy, where installations use environmentally friendly energy sources (passively clean plants), bioenergy plants (BES) are actively clean, which eliminates the environmental hazards of the products that are their raw materials.

There are many types of biogas plants in use around the world. They contain devices for receiving plant manure, metatanks and energy power units.

Methane tanks differ from each other in the design of devices for mixing the mass during fermentation. The most frequent mixing is carried out using a shaft with blades, which ensures layer-by-layer mixing of the fermented mass. In addition, they are mixed by hydraulic and mechanical devices, which ensure that the mass is taken from the lower layers of the digester and fed to the upper part. Biogas plants that operate in intensive mode have aerobic (oxygen) fermentation chambers, where the mass is prepared for fermentation, and anaerobic (methane) fermentation. There are also devices for mixing the mass, made in the form of a shaft with blades, located along the vertical axis of the housing and attached to the top of the floating gas cap. Mixing of the mass in the reactor occurs due to the rotation of the shaft with blades and the movement of the floating floor. Some devices only provide breaking of the crust that forms on the surface of the mass of the workpiece. Mixing is also achieved by using partitions and a double-acting siphon, which ensures alternate pouring of mass from the lower zone of one section to the upper zone of the second and, vice versa, by regulating the gas pressure. Sometimes the methane tank is designed in the form of a sphere or cylinder, which must be able to rotate around its geometric axis.

In Ukraine, due to the sharp rise in price of natural gas and the depletion of its resources, interest in biogas technologies has increased. Today, small biogas plants are not yet used in homesteads and small farms in the country. At the same time, for example, in China and India, millions of small methane tanks have been built and are successfully operating. In Germany, out of 3,711 operating biogas plants, about 400 are farm biogas plants, in Austria there are more than 100 of them.

Fig.45.German biogas plant (farm)

Fig.46 Diagram of a biogas plant for a farm:

1 - collections for pus (schematically); 2 - biomass loading system; 3- reactor 4 fermentation reactor; 5 - substrate; 6 - heating system; 7 - power plant; 8 - automation and control system; 9 - gas pipeline system.

Fig.47 Diagram of a biogas plant for a farm

According to the testimony of veterans of the Great Patriotic War, during the liberation of Romania they saw in many peasant households small primitive biogas installations that produced biogas used for domestic needs.

Among the small biogas plants, the ones developed by Biodieseldnepr LLC (Dnepropetrovsk) should be mentioned. They are intended for processing by anaerobic digestion (without access of oxygen) of organic waste from household plots and farms. Such installations make it possible to process 200-4000 kg of waste daily in a continuous mode or 1000-20000 kg in a cyclic mode for five days. At the same time, it is ensured that at least 3 m3 of biogas is obtained per 1 m3 of reactor volume, which can be used in installations to generate heat or electricity necessary to cover the energy needs of the installation; for gas supply systems (room lighting, cooking), heating and hot water supply for households; in plants for the synthesis of bioethanol and biodiesel fuel, as well as an appropriate amount of high-quality organic fertilizer, ready to be applied to the soil.

The industrial and commercial company "Dnepr-Desna" (Dnepropetrovsk) has developed a small bioenergy plant "Biogas-6MGS 2", intended for private households (3-4 cows, 10-12 pigs, 20-30 poultry). The productivity of this installation is approximately 11 m 3 of biogas per day.This amount of gas covers the heating needs of a 100 m 2 room and hot water for a family of five people.

The experience of introducing a small biogas plant in the village of Leski, Kenyan district, Odessa region, deserves attention. The biogas plant was developed and manufactured by a private company in Dnepropetrovsk.

The installation was installed within the framework of the project “Model for the disposal of livestock waste in the Danube Delta region”, developed by a group of Odessa non-governmental organizations within the framework of the program of small environmental projects with the financial support of the British Environment Fund for Europe and with the assistance of the Ministry of Environment and Food and British Agriculture and British Council.

Under normal loading and operation, a biogas plant with a reactor volume of 3 m3 will be able to produce up to 3 m3 of biogas per day by processing waste from 100 poultry, or 10 pigs, or 4 cows. These are the minimum requirements for the operation of the installation.

The reactor is installed on the surface of the earth. This is due, firstly, to the design of the reactor. Biological raw materials are loaded into it from below, through an extruder, and waste material is drained through the top, which distinguishes this design from others, in which loading occurs from above and selection from below. The second reason for the above-ground placement is the high level of soil water in the village - at a depth of 50 cm. In winter, heating of manure in the reactor is carried out using electricity, and in summer, solar energy is sufficient.

The resulting gas is used primarily for cooking - the gas pipeline is connected to the summer kitchen. It is necessary to maintain a temperature in the reactor of 30-35°C and monitor the production of biogas. Manure processed in a bioreactor must be unloaded in a timely manner.

As already noted, in Western Europe, biogas plants are being widely implemented on livestock farms. A feature of such installations is the introduction of power units, where biogas is converted into electricity, and the use of plant mass, in addition to manure.

It is advisable to use small feeders to feed plant mass into methane tanks. The capacity of the receiving hopper of such a feeder is 4 m3, the total length of the conveyor is 6 m; drive power - 7.5 kW.

The S-BOKH50 mini-power unit can be effectively used to complete farm biogas plants. The electrical power of such a power unit ranges from 25 to 48 kW; thermal power - from 49 to 97 kW.

Germany offers small compact biogas plants with a power of 30 and 100 kW, which are designed for the use of manure and corn silage. The 30 kW installation includes a storage loader for 5 m3 of solid organic matter, a concrete fermenter for 315 m3 and a USH gas motor with a power of 30 kW of electrical energy and 46 kW of thermal energy. To ensure the operation of a 30 kW biogas plant when using a mixture of 50% manure and 50% silage, it is necessary to have 5-7 hectares of corn. The 100 kW installation has a corn silage receiver-feeder with a capacity of up to 20 m3, a fermenter with a capacity of 1200 m3 and a gas engine with a power of 100 kW of electrical energy and 108 kW of thermal energy. When used to ensure the operation of a 100 kW biogas plant, a mixture of 50% manure and 50 % corn silage you need to have 30 hectares of corn.

It should be noted that when introducing biogas plants, foreign companies take an individual approach to each farmer. For a specific farm, after an appropriate examination of the available types and resources of biomass and determining the main purposes of using the installation, the appropriate technology (technological mode) is developed or selected, on the basis of which the installation (process line) is designed. The configuration depends on the selected technology. Most companies develop and install biogas plants on a turnkey basis. When using biogas plants, much attention is paid to technologies for preparing biomass for fermentation, since energy indicators depend on the quality of the raw materials. To effectively manage a biogas plant, it is advisable to use measuring and control technology.

The most effective technology is considered to be fermentation, which converts biogas energy into electrical and thermal energy.

Biogas production technology. Modern livestock breeding complexes ensure high production indicators. The technological solutions used make it possible to fully comply with the requirements of current sanitary and hygienic standards in the premises of the complexes themselves.

However, large quantities of liquid manure concentrated in one place create significant problems for the ecology of the areas adjacent to the complex. For example, fresh pig manure and droppings are classified as hazard class 3 waste. Environmental issues are under the control of supervisory authorities, and legislative requirements on these issues are constantly becoming more stringent.

Biocomplex offers a comprehensive solution for the disposal of liquid manure, which includes accelerated processing in modern biogas plants (BGU). During the processing process, natural processes of decomposition of organic matter occur in an accelerated mode with the release of gas including: methane, CO2, sulfur, etc. Only the resulting gas is not released into the atmosphere, causing a greenhouse effect, but is sent to special gas generator (cogeneration) units that generate electrical and thermal energy.

Biogas - flammable gas, formed during anaerobic methane fermentation of biomass and consisting mainly of methane (55-75%), carbon dioxide (25-45%) and impurities of hydrogen sulfide, ammonia, nitrogen oxides and others (less than 1%).

The decomposition of biomass occurs as a result of chemical and physical processes and the symbiotic life activity of 3 main groups of bacteria, while the metabolic products of some groups of bacteria are food products of other groups, in a certain sequence.

The first group is hydrolytic bacteria, the second is acid-forming, the third is methane-forming.

Both organic agro-industrial or household waste and plant raw materials can be used as raw materials for biogas production.

The most common types of agricultural waste used for biogas production are:

pig and cattle manure, poultry litter;
residues from the feeding table of cattle complexes;
vegetable tops;
substandard harvest of cereals and vegetables, sugar beets, corn;
pulp and molasses;
flour, spent grain, small grain, germ;
brewer's grain, malt sprouts, protein sludge;
waste from starch and syrup production;
fruit and vegetable pomace;
serum;
etc.

Source of raw materials	Type of raw material	Amount of raw materials per year, m3 (tons)	Amount of biogas, m3
1 milk cow	Unlittered liquid manure
1 fattening pig	Unlittered liquid manure
1 fattening bull	Litter solid manure
1 horse	Litter solid manure
100 chickens	Dry droppings
1 ha of arable land	Fresh corn silage
1 ha of arable land	Sugar beet
1 ha of arable land	Fresh grain silage
1 ha of arable land	Fresh grass silage

The number of substrates (types of waste) used to produce biogas within one biogas plant (BGU) can vary from one to ten or more.

Biogas projects in the agro-industrial sector can be created according to one of the following options:

biogas production from waste from a separate enterprise (for example, manure from a livestock farm, bagasse from a sugar factory, stillage from a distillery);
biogas production based on waste from different enterprises, with the project linked to a separate enterprise or a separately located centralized biogas plant;
biogas production with the primary use of energy plants at separately located biogas plants.

The most common method of energy use of biogas is combustion in gas piston engines as part of mini-CHP, producing electricity and heat.

Exist various options for technological schemes of biogas stations- depending on the types and number of types of substrates used. The use of preliminary preparation, in some cases, makes it possible to achieve an increase in the rate and degree of decomposition of raw materials in bioreactors, and, consequently, an increase in the overall yield of biogas. In the case of using several substrates with different properties, for example, liquid and solid waste, their accumulation and preliminary preparation (separation into fractions, grinding, heating, homogenization, biochemical or biological treatment, etc.) is carried out separately, after which they are either mixed before supplied to bioreactors, or supplied in separate streams.

The main structural elements of a typical biogas plant are:

system for receiving and preliminary preparation of substrates;
substrate transportation system within the installation;
bioreactors (fermenters) with a mixing system;
bioreactor heating system;
system for removal and purification of biogas from hydrogen sulfide and moisture impurities;
storage tanks for fermented mass and biogas;
system for software control and automation of technological processes.

Technological schemes of biogas plants vary depending on the type and number of processed substrates, the type and quality of the final target products, the particular know-how used by the company providing the technological solution, and a number of other factors. The most common today are schemes with single-stage fermentation of several types of substrates, one of which is usually manure.

With the development of biogas technologies, the technical solutions used are becoming more complex towards two-stage schemes, which in some cases is justified by the technological need for efficient processing of certain types of substrates and increasing the overall efficiency of using the working volume of bioreactors.

Features of biogas production is that it can be produced by methane bacteria only from absolutely dry organic substances. Therefore, the task of the first stage of production is to create a mixture of substrate that has a high content of organic substances, and at the same time can be pumped. This is a substrate with a dry matter content of 10-12%. The solution is achieved by releasing excess moisture using screw separators.

Liquid manure comes from the production premises into a tank, is homogenized using a submersible mixer, and is supplied by a submersible pump to the separation workshop into auger separators. The liquid fraction accumulates in a separate tank. The solid fraction is loaded into the solid raw material feeder.

In accordance with the schedule for loading the substrate into the fermenter, according to the developed program, the pump is periodically turned on, supplying the liquid fraction to the fermenter and at the same time the solid raw material loader is turned on. As an option, the liquid fraction can be fed into a solid raw material loader that has a mixing function, and then the finished mixture is fed into the fermenter according to the developed loading program. The inclusions are short-lived. This is done to prevent excessive intake of organic substrate into the fermenter, since this can upset the balance of substances and cause destabilization of the process in the fermenter. At the same time, pumps are also turned on, pumping digestate from the fermenter to the fermenter and from the fermenter to the digestate storage tank (lagoon) to prevent overflow of the fermenter and fermenter.

The digestate masses located in the fermenter and fermenter are mixed to ensure uniform distribution of bacteria throughout the entire volume of the containers. Low-speed mixers of a special design are used for mixing.

While the substrate is in the fermenter, bacteria release up to 80% of the total biogas produced by the biogas plant. The remaining part of the biogas is released in the digester.

An important role in ensuring a stable amount of biogas released is played by the temperature of the liquid inside the fermenter and fermenter. As a rule, the process proceeds in mesophilic mode with a temperature of 41-43ᴼС. Maintaining a stable temperature is achieved by using special tubular heaters inside fermenters and fermenters, as well as reliable thermal insulation of walls and pipelines. The biogas coming out of the digestate has a high sulfur content. Biogas is purified from sulfur using special bacteria that colonize the surface of the insulation laid on a wooden beam vault inside the fermenters and fermenters.

Biogas is accumulated in a gas holder, which is formed between the surface of the digestate and the elastic, high-strength material covering the fermenter and fermenter on top. The material has the ability to greatly stretch (without reducing strength), which, when biogas accumulates, significantly increases the capacity of the gas holder. To prevent the gas tank from overflowing and material rupture, there is a safety valve.

Next, the biogas enters the cogeneration plant. A cogeneration unit (CGU) is a unit in which electrical energy is generated by generators driven by gas piston engines running on biogas. Cogenerators running on biogas have design differences from conventional gas generator engines, since biogas is a highly depleted fuel. The electrical energy generated by the generators provides power to the electrical equipment of the BSU itself, and everything beyond this is supplied to nearby consumers. The energy of the liquid used to cool cogenerators is the generated thermal energy minus losses in boiler devices. The generated thermal energy is partially used to heat fermenters and fermenters, and the remaining part is also sent to nearby consumers. enters

It is possible to install additional equipment to purify biogas to the level of natural gas, however, this is expensive equipment and is used only if the purpose of the biogas plant is not the production of thermal and electrical energy, but the production of fuel for gas piston engines. The proven and most commonly used biogas purification technologies are aqueous absorption, pressurized adsorption, chemical precipitation and membrane separation.

The energy efficiency of biogas power plants largely depends on the chosen technology, materials and design of the main structures, as well as on the climatic conditions in the area where they are located. The average consumption of thermal energy for heating bioreactors in a temperate climate zone is 15-30% of the energy generated by cogenerators (gross).

The overall energy efficiency of a biogas complex with a biogas-fired thermal power plant averages 75-80%. In a situation where all the heat received from a cogeneration station during the production of electricity cannot be consumed (a common situation due to the lack of external heat consumers), it is released into the atmosphere. In this case, the energy efficiency of a biogas thermal power plant is only 35% of the total biogas energy.

The main performance indicators of biogas plants can vary significantly, which is largely determined by the substrates used, the adopted technological regulations, operational practice, and the tasks performed by each individual plant.

The manure processing process takes no more than 40 days. The digestate obtained as a result of processing is odorless and is an excellent organic fertilizer, in which the highest degree of mineralization of nutrients absorbed by plants is achieved.

Digestate is usually separated into liquid and solid fractions using screw separators. The liquid fraction is sent to lagoons, where it is accumulated until the period of application to the soil. The solid fraction is also used as fertilizer. If additional drying, granulation and packaging are applied to the solid fraction, it will be suitable for long-term storage and transportation over long distances.

Production and energy use of biogas has a number of advantages justified and confirmed by world practice, namely:

Renewable energy source (RES). Renewable biomass is used to produce biogas.
The wide range of raw materials used for the production of biogas allows the construction of biogas plants virtually everywhere in areas where agricultural production and technologically related industries are concentrated.
The versatility of the methods of energy use of biogas, both for the production of electrical and/or thermal energy at the place of its formation, and at any facility connected to the gas transportation network (in the case of supplying purified biogas to this network), as well as as motor fuel for cars.
The stability of electricity production from biogas throughout the year makes it possible to cover peak loads in the network, including in the case of using unstable renewable energy sources, for example, solar and wind power plants.
Creation of jobs through the formation of a market chain from biomass suppliers to operating personnel of energy facilities.
Reducing the negative impact on the environment through recycling and neutralization of waste through controlled fermentation in biogas reactors. Biogas technologies are one of the main and most rational ways to neutralize organic waste. Biogas production projects reduce greenhouse gas emissions into the atmosphere.
The agrotechnical effect of using mass fermented in biogas reactors on agricultural fields is manifested in improving soil structure, regeneration and increasing their fertility due to the introduction of nutrients of organic origin. The development of the market for organic fertilizers, including those from mass processed in biogas reactors, will in the future contribute to the development of the market for environmentally friendly agricultural products and increase its competitiveness.

Estimated unit investment costs

BGU 75 kWel. ~ 9.000 €/kWel.

BGU 150 kWel. ~ 6.500 €/kWel.

BGU 250 kWel. ~ 6.000 €/kWel.

BGU bis 500 kWel. ~ 4.500 €/kWel.

BGU 1 MWel. ~ 3.500 €/kWel.

The generated electrical and thermal energy can satisfy not only the needs of the complex, but also the adjacent infrastructure. Moreover, the raw materials for biogas plants are free, which ensures high economic efficiency after the payback period (4-7 years). The cost of energy generated at biogas power plants does not increase over time, but, on the contrary, decreases.

Biogas is a gas produced by the fermentation of biomass. In this way you can get hydrogen or methane. We are interested in methane as an alternative to natural gas. Methane is colorless and odorless and is highly flammable. Considering that the raw materials for producing biogas are literally under your feet, the cost of such gas is significantly less than natural gas, and you can save a lot on this. Here are the numbers from Wikipedia “From a ton of cattle manure, 50-65 m³ of biogas is obtained with a methane content of 60%, 150-500 m³ of biogas from various types of plants with a methane content of up to 70%. The maximum amount of biogas is 1300 m³ with a methane content of up to 87% can be obtained from fat.", "In practice, 300 to 500 liters of biogas are obtained from 1 kg of dry matter."

Tools and materials:
-Plastic container 750 liters;
-Plastic container 500 liters;
-Plumbing pipes and adapters;
-Cement for PVC pipes;
-Epoxy adhesive;
-Knife;
-Hacksaw;
-Hammer;
- Open-end wrenches;
-Gas fittings (details in step 7);

Step one: a little more theory
Some time ago, the master made a prototype of a biogas plant.

And he was bombarded with questions and requests to help with the assembly. As a result, even the state authorities became interested in the installation (the master lives in India).

The next step the master had to do a more complete installation. Let's consider what it is.
-The installation consists of a storage tank in which organic material is stored, and microorganisms process it and release gas.
-The gas thus obtained is collected in a reservoir known as a gas header. In the floating type model, this tank floats in suspension and moves up and down depending on the amount of gas stored in it
-The guide pipe helps the gas collector tank to move up and down inside the storage tank.
-Waste is fed through a supply pipe inside the storage tank.
-The completely recycled suspension flows through the outlet pipe. It can be collected, diluted and used as plant fertilizer.
-From the gas manifold, gas is supplied through a pipe to consumer appliances (gas stoves, water heaters, generators)

Step two: choosing a container
To select a container, you need to consider how much waste can be collected per day. According to the master, there is a rule where 5 kg of waste requires a container of 1000 liters. For a master it is approximately 3.5 - 4 kg. This means the capacity needed is 700-800 liters. As a result, the master purchased a capacity of 750 liters.
Installation with a floating type of gas manifold, which means you need to select a container such that gas losses are minimal. A 500 liter tank was suitable for these purposes. This 500 liter container will move inside the 750 liter container. The distance between the walls of the two containers is about 5 cm on each side. Containers need to be selected that will be resistant to sunlight and aggressive environments.

Step Three: Preparing the Tank
Cuts the top off the smaller tank. First, he makes a hole with a knife, then saws it with a hacksaw blade along the cut line.

The top part of the 750 liter container also needs to be cut off. The diameter of the cut part is the lid of the smaller tank + 4 cm.

Step four: supply pipe
An inlet pipe must be installed at the bottom of the larger tank. Biofuel will be poured inside through it. The pipe has a diameter of 120 mm. Cuts a hole in the barrel. Installs the knee. The connection is secured on both sides with cold welding epoxy glue.

Step five: pipe for draining the suspension
To collect the suspension, a pipe with a diameter of 50 mm and a length of 300 mm is installed in the upper part of a larger tank.

Step six: guides
As you already understood, a smaller one will “float” freely inside a large container. As the internal tank fills with gas, it will heat up and vice versa. To allow it to move freely up and down, the master makes four guides. In the “ears” he makes cutouts for a 32 mm pipe. Secures the pipe as shown in the photo. Pipe length 32 cm.

4 guides made of 40 mm pipes are also attached to the inner container.

Step seven: gas fittings
The gas supply is divided into three sections: from the gas manifold to the pipe, from the pipe to the cylinder, from the cylinder to the gas stove.
The master needs three 2.5 m pipes with threaded ends, 2 taps, sealing gaskets, threaded adapters, FUM tape and brackets for fastening.

To install the gas fittings, the master makes a hole in the upper part (formerly the lower part, i.e. the 500 liter cylinder is turned upside down) in the center. Installs the fittings, seals the joint with epoxy.

Step Eight: Assembly
Now you need to place the container on a flat, hard surface. The installation location should be as sunny as possible. The distance between the installation and the kitchen should be minimal.

Installs smaller diameter tubes inside the guide tubes. The pipe for draining excess suspension is extended.

Extends the inlet pipe. The connection is fixed using cement for PVC pipes.

Installs a gas accumulator inside a large tank. Orients it along the guides.

Step nine: first launch
For the initial start-up of a biogas plant of this volume, about 80 kg of cow manure is needed. Manure is diluted with 300 liters of non-chlorinated water. The master also adds a special additive to accelerate the growth of bacteria. The supplement consists of concentrated juice of sugar cane, coconut and palm trees. Apparently it's something like yeast. Fills this mass through the inlet pipe. After filling, the inlet pipe must be washed and a plug installed.

After a couple of days, the gas accumulator will begin to rise. This began the process of gas formation. As soon as the storage tank is full, the resulting gas must be vented. The first gas contains many impurities, and there was air in the storage tank.

Step ten: fuel
The process of gas formation has started and now we need to figure out what can and cannot be used as fuel.
So, the following are suitable for fuel: rotten vegetables, peelings of vegetables and fruits, unusable dairy products, overcooked butter, chopped weeds, waste from livestock and poultry, etc. A lot of unusable plant and animal waste can be used in the installation. The pieces need to be crushed as finely as possible. This will speed up the recycling process.

Do not use: onion and garlic peelings, eggshells, bones, fibrous materials.

Now let's look at the question of the amount of loaded fuel. As already mentioned, such a capacity requires 3.5 - 4 kg of fuel. Fuel processing takes from 30 to 50 days, depending on the type of fuel. Every day adding 4 kg of fuel, within 30 days about 750 g of gas will be produced from it daily. Overfilling the unit will lead to excess fuel, acidity and lack of bacteria. The master reminds that according to the rules, 5 kg of fuel is needed daily per 1000 liters of volume.
Step Eleven: Plunger
To make loading fuel easier, the master made a plunger.

One of the problems that has to be solved in agriculture is the disposal of manure and plant waste. And this is a rather serious problem that requires constant attention. Recycling takes not only time and effort, but also considerable amounts. Today there is at least one way to turn this headache into an income source: processing manure into biogas. The technology is based on the natural process of decomposition of manure and plant residues due to the bacteria they contain. The whole task is to create special conditions for the most complete decomposition. These conditions are the absence of oxygen access and optimal temperature (40-50 o C).

Everyone knows how manure is most often disposed of: they put it in heaps, then, after fermentation, they take it out to the fields. In this case, the resulting gas is released into the atmosphere, and 40% of the nitrogen contained in the initial substance and most of the phosphorus also escape there. The resulting fertilizer is far from ideal.

To obtain biogas, it is necessary that the process of decomposition of manure takes place without access to oxygen, in a closed volume. In this case, both nitrogen and phosphorus remain in the residual product, and the gas accumulates in the upper part of the container, from where it can be easily pumped out. There are two sources of profit: gas itself and effective fertilizer. Moreover, the fertilizer is of the highest quality and 99% safe: most of the pathogenic microorganisms and helminth eggs die, and the weed seeds contained in the manure lose their viability. There are even lines for packaging this residue.

The second prerequisite for the process of processing manure into biogas is maintaining an optimal temperature. The bacteria contained in the biomass are inactive at low temperatures. They begin to act at an ambient temperature of +30 o C. Moreover, manure contains two types of bacteria:

Thermophilic plants with temperatures from +43 o C to +52 o C are the most effective: in them, manure is processed for 3 days, and the output from 1 liter of useful bioreactor area is up to 4.5 liters of biogas (this is the maximum output). But maintaining a temperature of +50 o C requires significant energy expenditure, which is not profitable in every climate. Therefore, biogas plants often operate at mesophilic temperatures. In this case, the processing time can be 12-30 days, the yield is approximately 2 liters of biogas per 1 liter of bioreactor volume.

The composition of the gas varies depending on the raw materials and processing conditions, but it is approximately as follows: methane - 50-70%, carbon dioxide - 30-50%, and also contains a small amount of hydrogen sulfide (less than 1%) and very small amounts of ammonia, hydrogen and nitrogen compounds. Depending on the design of the plant, biogas may contain a significant amount of water vapor, which will require drying (otherwise it simply will not burn). What an industrial installation looks like is demonstrated in the video.

This can be said to be an entire gas production plant. But for a private farmstead or small farm such volumes are useless. The simplest biogas plant is easy to make with your own hands. But the question is: “Where should the biogas be sent next?” The heat of combustion of the resulting gas is from 5340 kcal/m3 to 6230 kcal/m3 (6.21 - 7.24 kWh/m3). Therefore, it can be supplied to a gas boiler to generate heat (heating and hot water), or to an electricity generation installation, to a gas stove, etc. This is how Vladimir Rashin, a biogas plant designer, uses manure from his quail farm.

It turns out that if you have at least a decent amount of livestock and poultry, you can fully meet your farm’s needs for heat, gas and electricity. And if you install gas installations on cars, then it will also provide fuel for the fleet. Considering that the share of energy resources in the cost of production is 70-80%, you can only save on a bioreactor, and then earn a lot of money. Below is a screenshot of an economic calculation of the profitability of a biogas plant for a small farm (as of September 2014). The farm cannot be called small, but it is definitely not large either. We apologize for the terminology - this is the author's style.

This is an approximate breakdown of the required costs and possible income Schemes for homemade biogas plants

Schemes of homemade biogas plants

The simplest scheme of a biogas plant is a sealed container - a bioreactor, into which the prepared slurry is poured. Accordingly, there is a hatch for loading manure and a hatch for unloading processed raw materials.

The simplest scheme of a biogas plant without any bells and whistles

The container is not completely filled with the substrate: 10-15% of the volume should remain free to collect gas. A gas outlet pipe is built into the tank lid. Since the resulting gas contains a fairly large amount of water vapor, it will not burn in this form. Therefore, it is necessary to pass it through a water seal to dry it. In this simple device, most of the water vapor will condense, and the gas will burn well. Then it is advisable to clean the gas from non-flammable hydrogen sulfide and only then can it be supplied to a gas holder - a container for collecting gas. And from there it can be distributed to consumers: fed to a boiler or gas oven. Watch the video to see how to make filters for a biogas plant with your own hands.

Large industrial installations are placed on the surface. And this, in principle, is understandable - the volume of land work is too large. But on small farms the bunker bowl is buried in the ground. This, firstly, allows you to reduce the cost of maintaining the required temperature, and secondly, in a private backyard there are already enough all kinds of devices.

The container can be taken ready-made, or made from brick, concrete, etc. in a dug pit. But in this case, you will have to take care of the tightness and impermeability of air: the process is anaerobic - without air access, therefore it is necessary to create a layer impenetrable to oxygen. The structure turns out to be multi-layered and the production of such a bunker is a long and expensive process. Therefore, it is cheaper and easier to bury a ready-made container. Previously, these were necessarily metal barrels, often made of stainless steel. Today, with the advent of PVC containers on the market, you can use them. They are chemically neutral, have low thermal conductivity, a long service life, and are several times cheaper than stainless steel.

But the biogas plant described above will have low productivity. To activate the processing process, active mixing of the mass located in the hopper is necessary. Otherwise, a crust forms on the surface or in the thickness of the substrate, which slows down the decomposition process, and less gas is produced at the outlet. Mixing is carried out in any available way. For example, as demonstrated in the video. In this case, any drive can be made.

There is another way to mix the layers, but it is non-mechanical - barbitation: the generated gas is fed under pressure into the lower part of the container with manure. Rising upward, gas bubbles will break the crust. Since the same biogas is supplied, there will be no changes in processing conditions. Also, this gas cannot be considered a consumption - it will again end up in the gas tank.

As mentioned above, good performance requires elevated temperatures. In order not to spend too much money on maintaining this temperature, you need to take care of insulation. What type of heat insulator to choose, of course, is up to you, but today the most optimal one is polystyrene foam. It is not afraid of water, is not affected by fungi and rodents, has a long service life and excellent thermal insulation performance.

The shape of the bioreactor can be different, but the most common is cylindrical. It is not ideal from the point of view of the complexity of mixing the substrate, but it is used more often because people have accumulated a lot of experience in building such containers. And if such a cylinder is divided by a partition, then they can be used as two separate tanks in which the process is shifted in time. In this case, a heating element can be built into the partition, thus solving the problem of maintaining temperature in two chambers at once.

In the simplest version, homemade biogas plants are a rectangular pit, the walls of which are made of concrete, and for tightness they are treated with a layer of fiberglass and polyester resin. This container is equipped with a lid. It is extremely inconvenient to use: heating, mixing and removal of the fermented mass is difficult to implement, and it is impossible to achieve complete processing and high efficiency.

The situation is a little better with trench biogas manure processing plants. They have beveled edges, making it easier to load fresh manure. If you make the bottom at a slope, then the fermented mass will shift to one side by gravity and it will be easier to select it. In such installations, it is necessary to provide thermal insulation not only for the walls, but also for the lid. It is not difficult to implement such a biogas plant with your own hands. But complete processing and the maximum amount of gas cannot be achieved in it. Even with heating.

The basic technical issues have been dealt with, and you now know several ways to build a plant for producing biogas from manure. There are still technological nuances.

What can be recycled and how to achieve good results

The manure of any animal contains the organisms necessary for its processing. It has been discovered that more than a thousand different microorganisms are involved in the fermentation process and gas production. Methane-forming substances play the most important role. It is also believed that all these microorganisms are found in optimal proportions in cattle manure. In any case, when processing this type of waste in combination with plant matter, the largest amount of biogas is released. The table shows average data for the most common types of agricultural waste. Please note that this amount of gas output can be obtained under ideal conditions.

For good productivity it is necessary to maintain a certain substrate humidity: 85-90%. But water must be used that does not contain foreign chemicals. Solvents, antibiotics, detergents, etc. have a negative effect on processes. Also, for the process to proceed normally, the liquid should not contain large fragments. Maximum fragment sizes: 1*2 cm, smaller ones are better. Therefore, if you plan to add herbal ingredients, you need to grind them.

It is important for normal processing in the substrate to maintain an optimal pH level: within 6.7-7.6. Usually the environment has normal acidity, and only occasionally acid-forming bacteria develop faster than methane-forming bacteria. Then the environment becomes acidic, gas production decreases. To achieve the optimal value, add regular lime or soda to the substrate.

Now a little about the time it takes to process manure. In general, the time depends on the conditions created, but the first gas can begin to flow already on the third day after the start of fermentation. The most active gas formation occurs when manure decomposes by 30-33%. To give you a sense of time, let’s say that after two weeks the substrate decomposes by 20-25%. That is, optimally the processing should last a month. In this case, the fertilizer is of the highest quality.

Calculation of bin volume for processing

For small farms, the optimal installation is a constant one - this is when fresh manure is supplied in small portions daily and removed in the same portions. In order for the process not to be disrupted, the share of the daily load should not exceed 5% of the processed volume.

Homemade installations for processing manure into biogas are not the pinnacle of perfection, but are quite effective

Based on this, you can easily determine the required tank volume for a homemade biogas plant. You need to multiply the daily volume of manure from your farm (already in a diluted state with a humidity of 85-90%) by 20 (this is for mesophilic temperatures, for thermophilic temperatures you will have to multiply by 30). To the resulting figure you need to add another 15-20% - free space for collecting biogas under the dome. You know the main parameter. All further costs and system parameters depend on which biogas plant scheme is chosen for implementation and how you will do everything. It is quite possible to make do with improvised materials, or you can order a turnkey installation. Factory developments will cost from 1.5 million euros, installations from the Kulibins will be cheaper.

Legal registration

The installation will have to be coordinated with the SES, gas inspectorate and firefighters. You will need:

Technological diagram of the installation.
Layout plan for equipment and components with reference to the installation itself, the installation location of the thermal unit, the location of pipelines and energy mains, and pump connections. The diagram should indicate the lightning rod and access roads.
If the installation will be located indoors, then a ventilation plan will also be required, which will provide at least an eightfold exchange of all the air in the room.

As we see, we cannot do without bureaucracy here.

Finally, a little about the performance of the installation. On average, per day a biogas plant produces a volume of gas twice the useful volume of the reservoir. That is, 40 m 3 of slurry will produce 80 m 3 of gas per day. Approximately 30% will be spent on ensuring the process itself (the main expense item is heating). Those. at the output you will receive 56 m 3 of biogas per day. According to statistics, to cover the needs of a family of three and to heat an average-sized house, 10 m 3 is required. In net balance you have 46 m3 per day. And this is with a small installation.

Results

By investing a certain amount of money in setting up a biogas plant (either with your own hands or on a turnkey basis), you will not only meet your own needs and needs for heat and gas, but will also be able to sell gas, as well as high-quality fertilizers resulting from processing.

The topic of alternative fuels has been relevant for several decades. Biogas is a natural fuel source that you can produce and use yourself, especially if you have livestock.

What it is

The composition of biogas is similar to that produced on an industrial scale. Stages of biogas production:

A bioreactor is a container in which biological mass is processed by anaerobic bacteria in a vacuum.
After some time, a gas is released consisting of methane, carbon dioxide, hydrogen sulfide and other gaseous substances.
This gas is purified and removed from the reactor.
Recycled biomass is an excellent fertilizer that is removed from the reactor to enrich fields.

Producing biogas with your own hands at home is possible provided that you live in a village and have access to animal waste. It is a good fuel option for livestock farms and agricultural enterprises.

The advantage of biogas is that it reduces methane emissions and provides an alternative energy source. As a result of biomass processing, fertilizer is formed for vegetable gardens and fields, which is an additional advantage.

To make your own biogas, you need to build a bioreactor to process manure, bird droppings and other organic waste. The raw materials used are:

wastewater;
straw;
grass;
river silt

It is important to prevent chemical impurities from entering the reactor, as they interfere with the processing process.

Use Cases

Processing manure into biogas makes it possible to obtain electrical, thermal and mechanical energy. This fuel is used on an industrial scale or in private homes. It is used for:

heating;
lighting;
heating water;
operation of internal combustion engines.

Using a bioreactor, you can create your own energy base to power your private home or agricultural production.

Thermal power plants using biogas are an alternative way to heat a private farm or small village. Organic waste can be converted into electricity, which is much cheaper than running it to the site and paying utility bills. Biogas can be used for cooking on gas stoves. The great advantage of biofuel is that it is an inexhaustible, renewable source of energy.

Biofuel efficiency

Biogas from litter and manure is colorless and odorless. It provides the same amount of heat as natural gas. One cubic meter of biogas provides the same amount of energy as 1.5 kg of coal.

Most often, farms do not dispose of waste from livestock, but store it in one area. As a result, methane is released into the atmosphere, and manure loses its properties as a fertilizer. Timely processed waste will bring much more benefits to the farm.

It is easy to calculate the efficiency of manure disposal in this way. The average cow produces 30-40 kg of manure per day. This mass produces 1.5 cubic meters of gas. From this amount, 3 kW/h of electricity is generated.

How to build a biomaterial reactor

Bioreactors are concrete containers with holes for the removal of raw materials. Before construction, you need to choose a location on the site. The size of the reactor depends on the amount of biomass you have daily. It should fill the container 2/3 full.

If there is little biomass, instead of a concrete container, you can take an iron barrel, for example, an ordinary barrel. But it must be strong, with high-quality welds.

The amount of gas produced directly depends on the volume of raw materials. In a small container you will get a little of it. To get 100 cubic meters of biogas, you need to process a ton of biological mass.

To increase the strength of the installation, it is usually buried in the ground. The reactor must have an inlet pipe for loading biomass and an outlet for removing waste material. There should be a hole at the top of the tank through which biogas is discharged. It is better to close it with a water seal.

For a correct reaction, the container must be hermetically sealed, without air access. The water seal will ensure timely removal of gases, which will prevent the system from exploding.

Reactor for a large farm

A simple bioreactor design is suitable for small farms with 1-2 animals. If you own a farm, it is best to install an industrial reactor that can handle large volumes of fuel. It is best to involve special companies involved in developing the project and installing the system.

Industrial complexes consist of:

Interim storage tanks;
Mixing installations;
A small thermal power plant that provides energy for heating buildings and greenhouses, as well as electricity;
Containers for fermented manure used as fertilizer.

The most effective option is to build one complex for several neighboring farms. The more biomaterial is processed, the more energy is produced as a result.

Before receiving biogas, industrial installations must be approved by the sanitary and epidemiological station, fire and gas inspection. They are documented; there are special standards for the location of all elements.

How to calculate reactor volume

The volume of the reactor depends on the amount of waste generated daily. Remember that the container only needs to be 2/3 full for effective fermentation. Also consider fermentation time, temperature and type of raw material.

It is best to dilute manure with water before sending it to the digester. It will take about 2 weeks to process manure at a temperature of 35-40 degrees. To calculate the volume, determine the initial volume of waste with water and add 25-30%. The volume of biomass should be the same every two weeks.

How to ensure biomass activity

For proper fermentation of biomass, it is best to heat the mixture. In the southern regions, the air temperature promotes the onset of fermentation. If you live in the north or in the middle zone, you can connect additional heating elements.

To start the process, a temperature of 38 degrees is required. There are several ways to ensure this:

A coil under the reactor connected to the heating system;
Heating elements inside the container;
Direct heating of the container with electric heating devices.

The biological mass already contains bacteria that are needed to produce biogas. They wake up and begin activity when the air temperature rises.

It is best to heat them with automatic heating systems. They turn on when cold mass enters the reactor and automatically turn off when the temperature reaches the desired value. Such systems are installed in water heating boilers; they can be purchased at gas equipment stores.

If you provide heating to 30-40 degrees, then processing will take 12-30 days. It depends on the composition and volume of the mass. When heated to 50 degrees, bacterial activity increases, and processing takes 3-7 days. The disadvantage of such installations is the high cost of maintaining high temperatures. They are comparable to the amount of fuel received, so the system becomes ineffective.

Another way to activate anaerobic bacteria is by stirring the biomass. You can install the shafts in the boiler yourself and move the handle out to stir the mass if necessary. But it is much more convenient to design an automatic system that will mix the mass without your participation.

Correct gas removal

Biogas from the manure is removed through the top cover of the reactor. It must be tightly closed during the fermentation process. Typically a water seal is used. It controls the pressure in the system; when it increases, the lid rises and the release valve is activated. A weight is used as a counterweight. At the outlet, the gas is purified with water and flows further through the tubes. Purification with water is necessary to remove water vapor from the gas, otherwise it will not burn.

Before biogas can be processed into energy, it must be accumulated. It should be stored in a gas tank:

It is made in the shape of a dome and installed at the outlet of the reactor.
Most often it is made of iron and coated with several layers of paint to prevent corrosion.
In industrial complexes, the gas tank is a separate tank.

Another option for making a gas holder: use a PVC bag. This elastic material stretches as the bag fills. If necessary, it can store large quantities of biogas.

Underground biofuel production plant

To save space, it is best to build underground installations. This is the easiest way to get biogas at home. To set up an underground bioreactor, you need to dig a hole and fill its walls and bottom with reinforced concrete.

Holes are made on both sides of the container for the inlet and outlet pipes. Moreover, the outlet pipe should be located at the base of the container for pumping out the waste mass. Its diameter is 7-10 cm. The entrance hole with a diameter of 25-30 cm is best located in the upper part.

The installation is covered with brickwork on top and a gas tank is installed to receive biogas. At the outlet of the container you need to make a valve to regulate the pressure.

A biogas plant can be buried in the yard of a private house and sewage and livestock waste can be connected to it. Recycling reactors can completely cover a family's electricity and heating needs. An additional benefit is getting fertilizer for your garden.

A DIY bioreactor is a way to get energy from pasture and make money from manure. It reduces farm energy costs and increases profitability. You can do it yourself or order installation. The price depends on the volume, starting from 7,000 rubles.