Biological gas (biogas) is a substance that consists of carbon dioxide (40%) and methane (60%). Its analogues are swamp gas, mine, sewer and methane.

If we take manure as an example, then if a ton of this biological waste is generated at an enterprise per day, approximately 50 m 3 of gas, or 100 kW of electrical energy, or 35 liters of diesel fuel can be obtained from this amount of material. Equipment for biogas production pays off in two to three years, and when using other types of raw materials, the period can be even less - about one and a half years.

Benefits of a biogas plant

A biogas plant will not only bring a cash profit to the company. There are also indirect benefits in its use. For example, it will cost much less than pulling power lines, gas pipelines, creating lagoons or backup diesel generators.

Biogas plants are modern bioreactor complexes. They work with minimal cost and high efficiency. Basically, equipment for the production of biogas is installed on the basis of livestock enterprises, complexes for the processing of agricultural products and other waste.

Purpose of the biogas plant

As a rule, biogas plants are used in the processing of waste from the food industry and agriculture. Thanks to such equipment, it is possible not only to use waste materials, but also to improve the environmental situation in production and processing areas.

In addition, an additional source of energy resources is provided. In fact, biogas equipment reduces the cycle of substances many times over, from several years to several weeks.

Components that a biogas plant should include

1. Homogenization tank.
2. Reactor.
3. Loader of raw materials: solid or liquid.
4. Gas holder.
5. Mixers.
6. Fuel and water connection system.
7. Gas system.
8. Separator.
9. Pumping station.
10. Control devices.
11. I&C with the possibility of visualization.
12. Safety system.

Raw waste is periodically fed into the reactor with the help of a loader or a pumping station. The reactor is a reinforced concrete tank, insulated and heated, equipped with mixers. It contains beneficial bacteria that feed on waste and produce biogas in the course of their life.

In order for the bacteria to be constantly viable, they need to be fed with food - salvage, ensure the temperature is not higher than 35 degrees and stir from time to time. The gas generated in the process is accumulated in a special storage (gas tank), and then, after passing through the purification system, it is fed to the end point, to the boiler or electric generator. The reactor is completely sealed and safe.

Use of biogas

Biogas is used as a fuel for generating heat, steam, electricity or for refueling vehicles. Equipment for the production of biogas can also be installed as a treatment plant in poultry farms, farms, meat processing plants, distilleries and sugar factories.

For new enterprises, the use of such an installation will significantly reduce start-up costs, since it will be possible not to spend money on laying power lines, gas pipelines, install diesel generators and build waste storage tanks. As a result, capital costs are reduced by about 30-40% of the cost of equipment for biogas production.

Many household owners are concerned about how to cut home heating, cooking and electricity costs. Some of them have already built biogas plants with their own hands and partially or completely separated themselves from energy suppliers. It turns out that getting almost free fuel in a private household is not very difficult.

What is biogas and how can it be used?

Owners of household plots know that by putting together any vegetable raw materials, bird droppings and manure, after a while you can get valuable organic fertilizer. But few of them know that biomass does not decompose by itself, but under the influence of various bacteria.

Processing the biological substrate, these tiny microorganisms release waste products, including a gas mixture. Most of it (about 70%) is methane - the same gas that burns in the burners of household stoves and heating boilers.

The idea of ​​using such eco-fuels for various household needs is not new. Devices for its extraction were used in ancient China. The possibility of using biogas was also explored by Soviet innovators in the 60s of the last century. But the technology experienced a real revival in the early 2000s. At the moment, biogas plants are actively used in Europe and the USA for heating houses and other needs.

How does a biogas plant work?

The principle of operation of the device for the production of biogas is quite simple:

• biomass diluted with water is loaded into a sealed container, where it begins to “ferment” and release gases;
• the contents of the tank are regularly updated - the raw materials processed by bacteria are drained and fresh ones are added (on average, about 5-10% daily);
• the gas accumulated in the upper part of the tank is supplied through a special tube to the gas collector, and then to household appliances.

Diagram of a biogas plant.

Which raw material is suitable for bioreactor?

Biogas plants are profitable only where there is a daily replenishment of fresh organic matter - manure or droppings from livestock and poultry. Also, crushed grass, tops, leaves and household waste (in particular, vegetable peelings) can be mixed into the bioreactor.

The efficiency of the installation largely depends on the type of feedstock. It has been proven that with the same mass, the largest biogas yield is obtained from pig manure and turkey manure. In turn, cow dung and silage produce less gas for the same load.

The use of bio-raw materials for home heating.

What cannot be used in a biogas plant?

There are factors that can significantly reduce the activity of anaerobic bacteria, or even completely stop the process of biogas production. Do not allow raw materials containing:

• antibiotics;
• mold;
• synthetic detergents, solvents and other "chemistry";
• resins (including sawdust of coniferous trees).

It is inefficient to use already rotting manure - only fresh or pre-dried waste is to be loaded. Also, waterlogging of raw materials should not be allowed - an indicator of 95% is already considered critical. However, it is still necessary to add a small amount of pure water to the biomass in order to facilitate its loading and speed up the fermentation process. Dilute manure and waste to the consistency of thin semolina.

Biogas plant for home

Today, the industry is already producing plants for biogas production on an industrial scale. Their purchase and installation is expensive, such equipment in private households pays off no earlier than in 7-10 years, provided that large volumes of organic matter are used for processing. Experience shows that, if desired, a skilled owner can build a small biogas plant for a private house with his own hands, and from the most affordable materials.

Preparing a processing bunker

First of all, you need a hermetically sealed cylindrical container. You can, of course, use large pots or boils, but their small volume does not allow sufficient gas production to be achieved. Therefore, for these purposes, plastic barrels with a volume of 1 m³ to 10 m³ are most often used.

You can make one yourself. PVC sheets are commercially available, with sufficient strength and resistance to aggressive environments, they are easily welded in the design of the desired configuration. A metal barrel of sufficient volume can also be used as a bunker. True, it will be necessary to carry out anti-corrosion measures - to cover it from the inside and outside with moisture-resistant paint. If the tank is made of stainless steel, this is not necessary.

Gas exhaust system

The gas outlet is mounted in the upper part of the barrel (usually in the lid) - this is where it accumulates, according to the laws of physics. Through a connected pipe, biogas is supplied to a water seal, then to a storage tank (as an option, using a compressor into a cylinder) and to household appliances. It is also recommended to install a release valve near the gas outlet - if the pressure inside the tank becomes too high, it will release excess gas.

Feeding and unloading system of raw materials

To ensure the continuous production of the gas mixture, the bacteria in the substrate must be constantly (daily) “feeded”, that is, fresh manure or other organic matter must be added. In turn, already processed raw materials must be removed from the bunker so that it does not take up useful space in the bioreactor.

To do this, two holes are made in the barrel - one (for unloading) is almost near the bottom, the other (for loading) is higher. Pipes with a diameter of at least 300 mm are welded (soldered, glued) into them. The loading pipeline is directed upwards and equipped with a funnel, and the drain is equipped so that it is convenient to collect the processed slurry (it can later be used as fertilizer). Joints are sealed.

heating system

Bunker insulation.

If the bioreactor is installed outdoors or in an unheated room (which is necessary for safety reasons), then it must be provided with thermal insulation and heating of the substrate. The first condition is achieved by "wrapping" the barrel with any insulating material or a recess in the ground.

As for heating, here you can consider a variety of options. Some craftsmen lead pipes inside, through which water from the heating system circulates and mount them along the walls of the barrel in the form of a coil. Others place the reactor in a larger tank with water inside, heated by electric heaters. The first option is more convenient and much more economical.

To optimize the operation of the reactor, it is necessary to maintain the temperature of its contents at a certain level (at least 38⁰C). But if it rises above 55⁰C, then the gas-producing bacteria will simply “cook” and the fermentation process will stop.

Mixing system

As practice shows, in designs, a hand stirrer of any configuration significantly increases the efficiency of the bioreactor. The axis, to which the blades of the “mixer” are welded (screwed), is output through the barrel lid. A gate handle is subsequently put on it, the hole is carefully sealed. However, home craftsmen do not always equip fermenters with such devices.

Biogas production

After the installation is ready, it is loaded with biomass, diluted with water in a ratio of approximately 2:3. In this case, large waste must be crushed - the maximum fraction size should not exceed 10 mm. Then the lid closes - it remains to wait for the mixture to begin to "ferment" and release biogas. Under optimal conditions, the first supply of fuel is observed a few days after loading.

The fact that the gas "went" can be judged by the characteristic gurgling in the water seal. At the same time, the barrel should be checked for leaks. This is done using an ordinary soapy solution - it is applied to all joints and observed to see if bubbles have appeared.

The first update of bio-raw materials should be carried out in about two weeks. After the biomass is poured into the funnel, the same volume of spent organics will pour out of the outlet pipe. Further, this procedure is performed daily or every two days.

How much biogas is produced?

In a small farm, a biogas plant will not become an absolute alternative to natural gas and other available energy sources. For example, using a device with a capacity of 1 m³, you can get fuel for only a couple of hours of cooking for a small family.

But with a bioreactor of 5 m³ it is already possible to heat a room of 50 m², but its work will need to be supported by a daily load of raw materials weighing at least 300 kg. To do this, you need to have about ten pigs, five cows and a couple of dozen chickens on the farm.

Masters who managed to independently make existing biogas plants share videos with master classes on the Internet:

Peculiarities of organic waste processing in household biological installations. Processing of organic waste without access to oxygen is a highly efficient 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 (CO 2 ). Various types of microorganisms metabolize carbon from organic substrates under oxygen-free conditions (anaerobic) (Table 4).

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

Methane digestion 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 evaluated as a local environmental 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 plant, three primary products are obtained: dehydrated sludge, biogas, liquid effluents. The dehydrated sludge is odorless, does not contain pathogenic microflora, the germination of weed seeds is reduced to zero. In general, dehydrated sludge is a highly concentrated decontaminated deodorized organic fertilizer suitable for direct application to the soil. It is also used as a raw material for the production of biohumus. Methane digestion improves the quality of the substrate. This is due to the fact that during methane fermentation without access to oxygen, ammonia nitrogen passes into the ammonium form, which further, in the process of aerobic fermentation, reduces nitrogen losses. The substrate obtained on the basis of fermented manure and manure contributes to an increase in crop yields by 15-40%.

Since 1920, biogas has been produced on a large scale from sewage wastewater. In European cities, since 1937, urban truck fleets began to be converted to run on biogas. During the Second World War and in the post-war period, the production of biogas from organic waste was researched and promoted. Due to the decrease in the cost of oil, the development of biogas technologies stopped in the 60s. In developing countries, simple biogas plants have become widespread. China has already created millions of such installations - "homestead" type. About 70 million installations have been built in India. In developed countries, after the crisis of 1973, large-volume biogas plants became widespread. It became 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 of the world, there are plants with a reactor volume from several to several thousand cubic meters. Conventionally, they can be divided into:

Small or backyard - the volume of the reactor is 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 - improvement of living conditions, which is especially important for rural residents.

In many countries, the potential offered by this method of waste processing is being used on a large scale. 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 has not stimulated the development of this energy technology, while in some countries, such as India and China, there have been national programs for recycling waste in bio-installations for a long time. A significant percentage of energy needs in many European countries is 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 discarding the importance of large-volume 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 their 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, the grinding of 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 necessary for fermentation, one should have another container and a certain amount of water. To reduce the cost of water, it is worth considering the possibility of its reuse. There are also problems with dehydration of the fermented mass. Most often, the units that are used for mechanization of work (grinding, mixing, heating, supply of processed products, etc.) at large plants are unsuitable for use at small ones due to their technical parameters and high cost.

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

The problems of operation of small biogas plants include the uneven process of obtaining biogas at different times of the year. In the summer period of operation, problems arise due to the fact that less biogas of own production will be spent on heating the substrate in the presence of a gas heater, its commercial amount will be greater than in the winter period. In the summer, when the animals are driven out to pasture, the amount of waste, the raw material for the operation of the bioreactor, also decreases. As part of such installations, it is impractical to provide nodes for a 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 efficient and profitable way to obtain high-quality organic fertilizers and an environmentally friendly energy source. Small household biogas-humus plants with a reactor 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 polycomponent substrates;

The use of "dry" type anaerobic fermentation for the production of biogas from energy crops;

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

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

It is advisable to use covered lagoons in a warm and temperate climate - for liquid manure that does not contain inclusions with a significant hydraulic fineness. Such reactors are not specially heated, and therefore they are considered not intensive. The duration of the decay of organic matter to stabilize the waste significantly exceeds that in reactors with an intensive digestion regime.

The reactors with an intensive digestion regime 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, mainly substrates are fermented with the dominance of liquid manure waste. The most common type of such reactors are cylindrical concrete or steel reactors 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 fermented mass of the reactor. The principal design of such reactors is shown in Figure 43.

Fig.43 . Vertical type methane tank

2 - substrate overflow;

3 - air supply pump;

4 - thermal insulation of the methane tank;

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

6 - mixing device;

7 - drive of the mixing device;

8 - service platform;

9 - gas tank membrane;

10 - filling level of the methantank;

11 - the height of the gas tank membrane;

12 - heating pipelines

Another type of reactor for liquid substrates is the horizontal type, operating on the principle of displacement. In such structures, the initial mixture of the substrate is supplied from one side, and removed from the other. In this case, the 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 separation in space of the points of entry of fresh substrates and the exit of fermented ones, it is possible to minimize the risk of an unfermented portion of fresh substrates exiting together with the fermented substrate (which is removed from the methanetank). Reactors of this type should be used for small volumes of fermented substrates.

Reactors of the following type are designed for methanization of dry organic mixtures, in which co-substrates from energy crops predominate. Reactors of this type are becoming widespread along with the spread of technologies for the "dry" fermentation of energy crops of plants. A characteristic feature of such methanetanks is that they are designed as full displacement reactors.

From technological positions, the process of obtaining biogas from organic matter is a multi-stage one. It consists of the process of preparing the substrates for digestion, the process of biological decomposition of the substance, after-fermentation (optional), the processing of the digested substrate and the extracted biogas, preparing them for use or disposal on site. Figure 2 shows a schematic diagram of a typical farm biogas plant for co-digestion of manure waste and organic co-substrates.

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

Preparation of the substrate for fermentation involves the collection and homogenization (mixing) of 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 later 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 co-substrates (if necessary).

After pre-treatment, a pre-calculated amount of the substrate is pumped with the help of pumps by a piping system to the reactor. In the reactor (methane tank), the substrate is destructible with the participation of microbiocenosis during the estimated time, depending on the chosen temperature regime. The methane tank is equipped with a system of heating pipelines, a mixing device (to eliminate the possibility of separation of the medium and the appearance of a crust, uniform division of nutrients for the microbiological environment and equalization of the temperature of the substrate), extraction systems for extracted biogas and removal of the fermented substrate. In addition, the methanetank 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 the separation system for separation into solid and liquid parts in a special separator.

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

The main substrate for anaerobic digestion, as a rule, is animal and poultry manure, as well as waste from slaughterhouses. 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 plants operate on a mixture of cosubstrates with different proportions. The country implemented a special program to collect data from more than 60 demonstrative operating biogas plants and analyzed them. There are quite a few stations (about 45%) where manure is used as the main substrate in the amount of 75-100% of the total volume of the mixture. However, there are also many stations where the content of manure runoff is less than 50%. This indicates that biogas plants in Germany in the production of biogas to a large extent use the potential of not only manure waste, but also a variety of additional co-substrates.

An analysis of data on biogas production at these stations showed that with an increase in the particle size of cosubstrates in the mixture, the specific yield of methane increases. Corn silage is the most common cosubstratum of various types. It is bought from farmers in crushed form, ready to be loaded into reactors, and stored in open fenced areas. In addition to corn silage, grass silage, grain chaff, fat waste, grass cuttings, whey, food and vegetable waste, and the like are widely used.

In the mind of a 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, is 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 underused due to low tariffs for electricity and heat, as a result of which the payback of BGU through the sale of energy is very low.

Of course, in order for biogas technologies to begin to develop actively, it is necessary to legalize the system of "green" tariffs for all types of renewable electrical and thermal energy, as has already taken place 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 efficient biogas plant is the biogas plant of the German company Envitek Biogas. The standard biogas plant of the company is equipped with a 2500 m3 reactor and a cogeneration unit with an electric power of 500 kW. The basic supplier of raw materials for such an installation can be a typical German pig farm with a population of 5,000 pigs. Increasing the yield of biogas is achieved by adding corn silage. For continuous operation of the installation throughout the year, 6,000 tons of silage, or 300 hectares of land, with a silage yield of 20 t/ha, are needed.

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

Biogas is used to produce electricity and heat energy. By burning 1 m3 of biogas, you can get 2.5-3 kWh 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 plant. Biogas under pressure 200-220 atm. can be used for refueling vehicles.

In addition to the production of energy and fertilizers during waste digestion, biogas plants play the role of treatment facilities - they reduce chemical and bacteriological pollution of soil, water, air and convert organic waste into neutral mineralized products. Compared to small river energy, wind and solar energy, where installations use environmentally friendly energy sources (passively clean installations), bioenergy installations (BEU) are actively clean, which eliminates the environmental hazard 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 power units.

Methantanks 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 provides layer-by-layer mixing of the fermented mass. In addition, they are mixed with hydraulic and mechanical devices that provide mass intake from the lower layers of the digester and supply to the upper part. Biogas plants that operate in intensive mode have chambers for aerobic (oxygen) fermentation, 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, placed along the vertical axis of the housing and attached to the upper part of the floating gas cap. Mixing of the mass in the reactor occurs due to the rotation of the shaft with the blades and the movement of the floating floor. Some devices provide only breaking the crust that forms on the surface of the mass of the workpiece. Mixing is also achieved by using baffles and a double-acting siphon, which provides alternate transfer of the mass from the lower zone of one section to the upper one of the second and, vice versa, by regulating the gas pressure. Sometimes the methane tank is made in the form of a sphere or a cylinder, which must be able to rotate around its geometric axis.

In Ukraine, due to a sharp rise in the price of natural gas, the exhaustibility 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, millions of small methanetanks have been built and successfully operated in China and India. In Germany, out of 3711 operating biogas plants, about 400 are farm biogas plants, in Austria there are more than 100.

Fig.45.German biogas plant (farm)

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

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

Fig. 47 Scheme 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 small primitive biogas plants in many peasant households that produced biogas used for domestic needs.

Of the small biogas plants, it is worth mentioning the plants developed by Biodieseldnepr LLC (Dnepropetrovsk). They are intended for processing by anaerobic digestion (without oxygen access) of organic waste from household and farm households. Such installations allow processing 200-4000 kg of waste daily in continuous mode or 1000-20000 kg - cyclically, for five days. At the same time, at least 3 m3 of biogas per 1 m3 of the reactor volume is obtained, which can be used in plants to produce heat or electricity needed to cover the energy needs of the plant; for gas supply systems (room lighting, cooking), heating and hot water supply of the economy; 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.

Production and commercial company "Dnepr-Desna" (Dnepropetrovsk) has developed a small bioenergy plant "Biogas-6MGS 2", designed for private households (3-4 cows, 10-12 pigs, 20-30 poultry). The plant produces approximately 11 m 3 of biogas per day, which covers the heating and hot water needs of a 100 m 2 house for a family of five.

Noteworthy is the experience of introducing a small biogas plant in the village of Leski, Kenya district, Odessa region. The biogas plant is designed and manufactured by a private company in Dnepropetrovsk.

The installation was installed within the framework of the project "Animal Waste Management Model in the Danube Delta Region", developed by a group of Odessa non-governmental organizations within the framework of a program of small environmental projects with financial support from the British Environment Fund "Environment for Europe" and with the assistance of the Ministry of Environment, Food and Agriculture of Britain and the 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 due to the processing of waste from 100 poultry, or from 10 pigs, or from 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. The loading of biological raw materials into it is carried out from below, through the extruder, and the waste material is drained through the top, which distinguishes the noted design from others, in which the loading is from above, and the selection is from below. The second reason for land placement is the high level of soil water in the village - at a depth of 50 cm. In winter, manure in the reactor is heated by electricity, and in summer there is enough solar energy.

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

As already noted, in Western Europe, livestock farms are widely introduced biogas plants. A feature of such plants is the introduction of energy-power units into their composition, where biogas is converted into electricity, and the use, in addition to manure, of plant mass.

It is advisable to use small feeders to supply plant mass to the methanetanks. 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 mini-energy-power unit "S-BOX50" can be effectively used to complete farm biogas plants. The electric power of such a power unit is from 25 to 48 kW; thermal power - from 49 to 97 kW.

Germany offers small compact biogas plants with a capacity of 30 and 100 kW, which are designed for the use of manure and corn silage. The 30 kW plant includes a 5 m3 solid organic mass storage-loader, a 315 m3 concrete fermenter and a 30 kW electric and 46 kW thermal USH gas engine. To ensure the operation of a 30 kW biogas plant in the case of using a mixture of 50% manure and 50% silage, it is necessary to have 5-7 hectares of corn. The 100 kW unit has a corn silo feeder with a capacity of up to 20 m3, a fermenter with a capacity of 1200 m3 and a gas engine with a capacity of 100 kW of electrical and 108 kW of thermal energy. When used to ensure the operation of a biogas plant for 100 kW of 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 apply an individual approach to each farmer. For a specific farm, after an appropriate examination of the available types and resources of biomass and the determination of the main purposes of using the installation, an appropriate technology (technological regime) is developed or selected, on the basis of which the installation (process line) is designed. The complete set depends on the chosen technology. Most companies develop and install turnkey biogas plants. When using biogas plants, much attention is paid to technologies for preparing biomass for fermentation, since energy indicators depend on the quality of raw materials. For effective control of a biogas plant, it is advisable to use measuring and control technology.

The most efficient technology is considered to be digestion with the conversion of biogas energy into electrical and thermal energy.

A prudent owner dreams of cheap energy resources, efficient waste disposal and obtaining fertilizers. A do-it-yourself home biogas plant is an inexpensive way to make dreams come true.

Self-assembly of such equipment will cost reasonable money, and the gas produced will be a good help in the household: it can be used for cooking, heating the house and other needs.

Let's try to understand the specifics of this equipment, its advantages and disadvantages. And also whether it is possible to independently build a biogas plant and whether it will be effective.

Biogas is formed as a result of the fermentation of a biological substrate. It is decomposed by hydrolytic, acid- and methane-forming bacteria. The mixture of gases produced by bacteria turns out to be combustible, because. contains a large percentage of methane.

By its properties, it practically does not differ from natural gas, which is used for industrial and domestic needs.

If desired, each home owner can purchase an industrial biogas plant, but it is expensive, and the investment pays off within 7-10 years. Therefore, it makes sense to make an effort and make a bioreactor with your own hands.

Biogas is an environmentally friendly fuel, and the technology for its production does not have a particular impact on the environment. Moreover, as a raw material for biogas, waste products that need to be disposed of are used.

They are placed in a bioreactor where processing takes place:

• for some time, the biomass is exposed to bacteria. The fermentation period depends on the volume of raw materials;
• as a result of the activity of anaerobic bacteria, a combustible mixture of gases is released, which includes methane (60%), carbon dioxide (35%) and some other gases (5%). Also, during fermentation, potentially dangerous hydrogen sulfide is released in small quantities. It is poisonous, so it is highly undesirable for people to be exposed to it;
• the mixture of gases from the bioreactor is cleaned and enters the gas tank, where it is stored until it is used for its intended purpose;
• gas from a gas tank can be used in the same way as natural gas. It goes to household appliances - gas stoves, heating boilers, etc.;
• decomposed biomass must be regularly removed from the fermenter. This is an additional effort, but the effort pays off. After fermentation, the raw material turns into high-quality fertilizer, which is used in fields and gardens.

A biogas plant is beneficial for the owner of a private house only if he has constant access to waste from livestock farms. On average, out of 1 cubic meter. substrate can be obtained 70-80 cubic meters. biogas, but gas production is uneven and depends on many factors, incl. biomass temperature. This complicates the calculations.

Biogas plants. Biogas production

Complete stainless steel plants for biogas production.

Biogas plants are a comprehensive solution for the disposal of waste from the food industry, the agro-industrial complex, the production of heat, electricity, and fertilizers. The production of methane in a biogas plant is the implementation of a biological process.

The German company designs and manufactures complete biogas plants and sells them all over the world. More than 300 biogas plants have been built, launched and are successfully operating in Germany, France, the Netherlands, Greece, Great Britain, Sweden, Spain, Luxembourg, Czech Republic, Lithuania, USA, Japan and Cyprus. The proposed installations are not experimental, but working, tested and reliable German equipment, certified according to ISO and manufactured as a set at our own factory.

We will show you how you can use bioenergy intelligently and economically.

Biogas is a gas composed of approximately 60% methane (CH4) and 40% carbon dioxide. Synonyms for biogas are sewer gas, mine gas and swamp gas, methane gas. If we consider manure as an example, then if the enterprise generates 1 ton of such “bio-waste” per day, then this means that 50 m3 of gas or 100 kW of electricity can be obtained from it, or 35 liters of diesel fuel can be replaced. The payback period for manure processing equipment is within 2-3 years, and for some other types of raw materials it is even lower and reaches 1.5 years. In addition to direct monetary benefits, the construction of a biogas plant has indirect benefits. For example, it is cheaper than pulling a gas pipeline, power lines, backup diesel generators and creating lagoons. The table shows the gas yield for various types of raw materials.

SOURCES OF RAW MATERIALS

An important area of ​​application for biogas plants is large agro-industrial complexes, cattle farms, poultry farms, fish factories, bakeries, food processing plants, meat processing plants, distilleries, breweries, dairies, crop plants, sugar factories, starch factories, enterprises for yeast production, and not only as an alternative source of energy, but also as an effective method of manure (dung) disposal and the production of cheap fertilizer, both for own needs and for sale on the market. The biogas plant produces biogas and biofertilizers from organic waste from agriculture and the food industry through oxygen-free fermentation, which provides the most active cleaning system. Can be used as raw materials: cattle manure, pig manure, poultry manure, slaughterhouse waste (blood, fat, intestines, bones), plant waste, silage, rotten grain, sewage, fats, biowaste, food industry waste, garden waste, malt sludge , pomace, distillery stillage, beet pulp, technical glycerin (from biodiesel production). Most raw materials can be mixed with each other. Waste recycling is primarily a cleaning system that pays for itself and makes a profit. At the outlet of the plant, waste is produced simultaneously and in large quantities: biogas, electricity, heat and fertilizers.

All of the above is produced at zero cost. After all, manure is free, and the installation itself consumes only 10-15% of energy. For the operation of a powerful installation, one person is enough for two hours a day. Biogas plants are fully automated and, accordingly, labor costs are minimal.

Technology and principle of operation of a biogas plant

The biogas plant produces biogas and biofertilizers from biological waste from agriculture and the food industry through oxygen-free fermentation. Biogas is a waste product of beneficial methane-forming bacteria. Microorganisms metabolize carbon from organic substrates under anoxic conditions (anaerobically). This process, called putrefaction or anoxic fermentation, follows the food chain.

Composition of a typical biogas plant:

Biowaste can be delivered by trucks or pumped to the biogas plant. First, the coenzymes are poured out (ground), homogenized and mixed with manure (litter). Homogenization is most often carried out at 70°C for one hour with a maximum particle size of 1 cm. Homogenization with manure is carried out in a mixing tank with powerful agitators.

The reactor is a gas-tight, fully sealed vessel. This design is thermally insulated, because the temperature inside the tank must be fixed for microorganisms. Inside the reactor is a mixer designed to completely mix the contents of the reactor. Conditions are created for the absence of floating layers and/or sediment.

Microorganisms must be provided with all the necessary nutrients. Fresh feed should be fed into the reactor in small portions several times a day. The average time of hydraulic settling inside the reactor (depending on substrates) is 20-40 days. During this time, organic substances within the biomass are metabolized (transformed) by microorganisms. At the outlet of the plant, two products are formed: biogas and substrate (composted and liquid).

The biogas is stored in a gas storage tank, where the pressure and composition of the gas are equalized. From the gas tank there is a continuous supply of gas to the gas engine generator. Heat and electricity are already produced here. If necessary, biogas is purified to natural gas (95% methane) after such purification, the resulting gas is an analogue of natural gas (90-95% methane CH4). The only difference is in its origin.

Biogas plants operate 24 hours a day, 7 days a week, all year round. This mode of operation is another advantage. The whole system is controlled by an automation system. Only one person is enough to manage two hours a day.

This employee controls with a simple computer and also works on a tractor to feed the biomass. After 2 weeks of training, a person without special skills can work on the unit, i.e. with secondary or secondary special education.

BENEFITS

• Biogas.
• Own bioenergy station.
• Proper disposal of organic waste. Waste to income!
• Biofertilizers. When using fertilizers obtained from biogas plants, yields can be increased by 30-50%. Ordinary manure, bard or other waste cannot be effectively used as fertilizer for 3-5 years. When using a biogas plant, biowaste is fermented and the fermented mass can immediately be used as a highly effective biofertilizer. The fermented mass is ready-made environmentally friendly liquid and solid biofertilizers, devoid of nitrites, weed seeds, pathogenic microflora, helminth eggs, and specific odors. When using such balanced biofertilizers, the yield increases significantly.
• Electricity. By installing a biogas plant, the enterprise will have its own, in fact, free electricity, which means a significant reduction in the cost of production, which in turn will allow the latter to gain additional competitive advantages.
• Warm. The heat from generator cooling or biogas combustion can be used to heat an enterprise, greenhouses, technological purposes, get steam, dry seeds, dry firewood, get boiled water for livestock. The enterprise receives gas, electricity, heat, fertilizers and provides a closed production cycle. The project pays off by reducing the cost of products manufactured by the enterprise, as the cost of buying gas, electricity, hot water and fertilizers is reduced.
• Additional profit can be used to repay the loan and to develop production. Reduction of energy dependence, reduction of greenhouse gas emissions, reduction of environmental pollution by agricultural waste, absence of an unpleasant smell at the enterprise.

The construction of a biogas plant is relevant not only for newly created farms, but also for old ones. Indeed, often the old lagoons are overcrowded, and their repair requires significant funds. While some wastes can simply be stored in lagoons, some (such as slaughterhouse waste) require energy and expense to dispose of. Site requirements. The installation can be located on the site of lagoons, lagoons or an old landfill. The average size of the site for installation is 40x70 m.

Biogas plant price

Each enterprise is individual, therefore, in each case, financial costs will be calculated by specialists.

Project example

We give an example of average costs and revenues for the installation of biogas equipment.
Calculation of costs and revenues on the example of a biogas plant for a distillery. The installation cost is 1280 thousand euros. All services and works included. Productivity on a grain bard is 100 tons a day.

Humidity of the separated bard is 70%. The average payback period of the project is 2-3 years. And with full use of the installation's capabilities, the payback can be 1.5-1.8 years. The use of opportunities is the addition of coenzymes, the use of heat in greenhouses, the sale of all fertilizers produced.

Energy costs are one of the main cost items that significantly affect the cost of production. Wastewater treatment plants consume about 50% of energy, and when building a biogas plant, this 50% is saved. The enterprise receives gas, electricity, heat, fertilizers and provides a closed production cycle.

The project pays off by reducing the cost of production, as the cost of buying gas, electricity, hot water and fertilizers is reduced. Additional profit can be used to repay the loan and to develop production.

The material was prepared by Shilova E.P.