Do-it-yourself home biogas plant. Biogas plants. Work and device. Biogas and application Biogas plant for a private house diagram

The theoretical basis for the production of methane gas from biomass by anaerobic digestion was presented.

The role of bacteria in the step-by-step transformation of organic substances was explained, with a description of the necessary conditions for the most intensive production of biogas. This article will provide practical implementations of biogas plants, with a description of some home-made designs.

Since energy prices are rising, and many owners of livestock farms and small farms have problems with waste disposal, industrial complexes for the production of biogas and small biogas plants for private homes have become available for sale. Using search engines, an Internet user can easily find an affordable ready-made solution so that the biogas plant and its price meet the needs, get in touch with equipment suppliers and agree on the construction of a biogas generator at home or on the farm.

Industrial complex for biogas production

Bioreactor - the basis of a biogas plant

The container in which anaerobic decomposition of biomass occurs is called bioreactor, fermenter, or methane tank. Bioreactors can be completely sealed, with a fixed or floating dome, and have a diving bell design. Bell psychrophilic (not requiring heating) bioreactors have the form of an open reservoir with liquid biomass, into which a container in the form of a cylinder or bell is immersed, where biogas is collected.

The collected biogas puts pressure on the cylinder, causing it to rise above the tank. Thus, the bell also serves as a gas holder - a temporary storage facility for the generated gas.

Floating dome bioreactor

The disadvantage of the bell design of the biogas reactor is the impossibility of mixing the substrate and heating it during cold periods of the year. Also a negative factor is a strong odor, and unsanitary conditions due to the exposed surface of part of the substrate.

In addition, part of the resulting gas will escape into the atmosphere, polluting the environment. Therefore, these bioreactors are used only in artisanal biogas plants in poor countries with hot climates.

Another example of a bioreactor with a floating dome

To prevent environmental pollution and eliminate unpleasant odors, reactors in biogas plants for homes and large industries are designed with a fixed dome. The shape of the structure in the process of gas formation is not of great importance, but when using a cylinder with a dome-shaped roof, significant savings in building materials are achieved. Bioreactors with a fixed dome are equipped with pipes for adding new portions of biomass and selecting spent substrate.

A type of fixed dome bioreactor

Main types of biogas plants

Since the most acceptable design is a fixed dome, most ready-made bioreactor solutions are of this type. Depending on the loading method, bioreactors have different designs and are divided into:

• Portion-based, with a one-time loading of all biomass, and subsequent complete unloading after processing of raw materials. The main disadvantage of this type of bioreactor is the uneven release of gas during substrate processing;
• continuous loading and unloading of raw materials, thereby achieving uniform release of biogas. Thanks to the design of the bioreactor, during loading and unloading, the production of biogas does not stop and no leaks occur, since the pipes through which biomass is added and removed are made in the form of a water seal that prevents gas leakage.

Example of a batch bioreactor

Batch biogas reactors can have any design that prevents gas leakage. For example, at one time in Australia, channel methane tanks with an elastic inflatable roof were popular, where a slight excess pressure inside the bioreactor inflated a bubble made of durable polypropylene. When a certain pressure level inside the bioreactor was reached, a compressor was turned on, pumping out the produced biogas.

Channel bioreactors with elastic gas holder

The type of fermentation in this biogas plant can be mesophilic (with low heating). Due to the large area of ​​the inflating dome, channel bioreactors can only be installed in heated rooms or in regions with a hot climate. The advantage of the design is that there is no need for an intermediate receiver, but the big disadvantage is the vulnerability of the elastic dome to mechanical damage.

Large channel bioreactor with elastic gas tank

Recently, batch bioreactors with dry fermentation of manure without adding water to the substrate have been gaining popularity. Since manure has its own moisture, it will be sufficient for the life of organisms, although the intensity of reactions will decrease.

Dry-type bioreactors look like a sealed garage with tightly closing doors. Biomass is loaded into the reactor using a front-end loader and remains in this state until the full gas formation cycle is completed (about six months), without the need to add a substrate or mix it.

Batch bioreactor with loading through a hermetically sealed door

DIY biogas plant

It should be noted that in most bioreactors, as a rule, only the gas formation zone is sealed, and the liquid biomass at the inlet and outlet is under atmospheric pressure. Excessive pressure inside the bioreactor displaces part of the liquid substrate into the nozzles, which is why the level of biomass in them is slightly higher than inside the container.

The red lines in the diagram indicate the difference in levels in the bioreactor and pipes

These designs of homemade bioreactors are popular among folk craftsmen who independently make biogas plants with their own hands for the home, allowing for repeated manual loading and unloading of the substrate. When making bioreactors with their own hands, many craftsmen experiment with completely sealed containers, using several rubber tubes from the tires of large vehicles as a gas holder.

Drawing of a gas holder made from tractor inner tubes

In the video below, an enthusiast of homemade biogas production, using barrels filled with bird droppings as an example, proves the possibility of actually producing combustible gas at home by processing poultry house waste into useful fertilizer. The only thing that can be added to the design described in this video is that you need to install a pressure gauge and a safety valve on a homemade bioreactor.

Bioreactor productivity calculations

The amount of biogas is determined by the mass and quality of the raw materials used. On the Internet you can find tables that indicate the amount of waste produced by various animals, but for owners who have to remove manure every day, this theory is of no use, since thanks to their own practice they know the amount and mass of the future substrate. Based on the availability of raw materials renewable every day, it is possible to calculate the required volume of the bioreactor and the daily biogas production.

Table for obtaining the amount of manure from some animals with an approximate calculation of biogas yield

After the calculations have been made and the design of the bioreactor has been approved, its construction can begin. The material can be a reinforced concrete container poured into the ground, or brickwork sealed with a special coating that is used to treat swimming pools.

It is also possible to build the main tank of a home biogas plant from iron coated with anti-corrosion material. Small industrial bioreactors are often made from large-volume, chemical-resistant plastic tanks.

Construction of a bioreactor from brickwork

In industrial biogas plants, electronic control systems and various reagents are used to correct the chemical composition of the substrate and its acidity level, and special substances are added to the biomass - enzymes and vitamins that stimulate the reproduction and vital activity of microorganisms inside the bioreactor. In the process of development of microbiology, more and more stable and effective strains of methanogen bacteria are being created, which can be purchased from companies involved in the production of biogas.

The graph shows that with the use of enzymes, the maximum biogas yield occurs twice as fast

The need for pumping out and purifying biogas

Constant gas production in a bioreactor of any design leads to the need to pump out biogas. Some primitive biogas plants can burn the resulting gas directly in a burner installed nearby, but instability of the excess pressure in the bioreactor can lead to the disappearance of the flame with subsequent release poisonous gas. The use of such a primitive biogas installation connected to a stove is categorically unacceptable due to the possibility of poisoning by the toxic components of unpurified biogas.

The burner flame when burning biogas must be clean, even and stable.

Therefore, almost any biogas installation scheme includes gas storage tanks and a gas purification system. As a homemade cleaning complex, you can use a water filter and a homemade container filled with metal shavings, or purchase professional filtration systems. A container for temporary storage of biogas can be made from inner tubes from tires, from which the gas is pumped out from time to time by a compressor into standard propane cylinders for storage and subsequent use.

In some African countries, inflatable gas holders in the form of a pillow are used for storing and transporting biogas

An improved bioreactor with a floating dome can be considered as an alternative to the mandatory use of a gas tank. The improvement consists of adding a concentric partition, which forms a water pocket, acting like a water seal and preventing the biomass from coming into contact with air. The pressure inside the floating dome will depend on its weight. By passing the gas through a cleaning system and a reducer, it can be used in a household stove, periodically venting it from the bioreactor.

Bioreactor with floating dome and water pocket

Grinding and mixing the substrate in a bioreactor

Stirring the biomass is an important part of the biogas production process, providing bacteria with access to nutrients that may be clumped at the bottom of the digester. In order for biomass particles to be better mixed in the bioreactor, they must be crushed mechanically or manually before loading into the methane tank. Currently, in industrial and home-made biogas plants, three methods of mixing the substrate are used:

1. mechanical stirrers, driven by an electric motor or manually;
2. circulation mixing using a pump or propeller pumping the substrate inside the bioreactor;
3. bubbling mixing using purging of liquid biomass with existing biogas. The disadvantage of this method is the formation of foam on the surface of the substrate.

The arrow indicates the mixing circulation screw in a homemade bioreactor

Mechanical mixing of the substrate inside the bioreactor can be done manually or automatically by turning on the electric motor using an electronic timer. Water jet or bubbling mixing of biomass can only be carried out using electric motors controlled manually or using a software algorithm.

This bioreactor is equipped with a mechanical mixing device.

Substrate heating in mesophilic and thermophilic biogas plants

The optimum temperature for gas formation is the substrate temperature within 35-50ºC. To maintain this temperature, various heating systems– water, steam, electric. Temperature control should be carried out using a thermostat or thermocouples connected to an actuator that regulates the heating of the bioreactor.

You also need to remember that an open flame will overheat the walls of the bioreactor, and the biomass inside will burn. A burnt substrate will reduce heat transfer and heating quality, and the hot wall of the bioreactor will quickly collapse. One of the best options is water heating from the return pipe of the home heating system. It is necessary to install a system of electric valves to be able to turn off the heating of the bioreactor or connect the heating of the substrate directly from the boiler if it is too cold.

Electric and water heating system for the bioreactor

Heating the substrate in a bioreactor using heating elements will be beneficial only if alternative electricity is available, obtained from a wind generator or solar panels. In this case, heating elements can be connected directly to a generator or battery, which eliminates expensive voltage converters from the circuit. To reduce heat loss and reduce the cost of heating the substrate in a bioreactor, it is necessary to insulate it as much as possible using various insulation materials.

Insulation of the bioreactor with thermal insulation material

Practical experiments inevitable when building biogas plants with your own hands

No matter how much literature a novice enthusiast of self-production of biogas reads, and no matter how many videos he watches, in practice he will have to learn a lot on his own, and the results, as a rule, will be far from the calculated ones.

Therefore, many beginning craftsmen follow the path of independent experiments in producing biogas, starting with small containers, determining how much gas their small experimental biogas plant produces from the available raw materials. Prices for components, methane output and future costs of building a full-fledged working biogas plant will determine its profitability and feasibility.

In the video above, the master demonstrates the capabilities of his biogas installation, measuring how much biogas is produced in one day. In his case, when eight atmospheres are pumped into the compressor receiver, the volume of the resulting gas after recalculation taking into account the volume of the 24 liter container will be about 0.2 m².

This volume of biogas obtained from a two-hundred-liter barrel is not significant, but, as shown in the following video of this master, this amount of gas is enough for an hour of burning one stove burner (15 minutes multiplied by four atmospheres of a cylinder, which is twice the size of the receiver).

In another video below, the master talks about producing biogas and biologically pure fertilizers by processing organic waste in a biogas plant. It must be borne in mind that the value of environmental fertilizers may exceed the cost of the resulting gas, and then biogas will become a useful by-product of the process of producing quality fertilizers. Another useful property of organic raw materials is the ability to store them for a certain period for use at the right time.

Biogas plants for farms, the price depends on the number of components, various parameters characteristic of such devices, varies within 170 thousand rubles.

They work to obtain, as a result of processing the final product, environmentally friendly fuel and fertilizers, which are produced in the unit, which includes technical structures and devices combined in a single technological cycle.

Biogas plants for the home may one day completely replace expensive energy sources for rural residents. Economic cataclysms require developers of agricultural equipment to produce analogues of natural resources in the form of improvised raw materials to reduce the cost of maintaining a private farmstead and farming.

The goals of farmers are different - some get cheap energy, while others need to use a small mini-installation to process waste:

• cattle

As a result of the work, they obtain biofertilizers and their own energy source. In addition, farms have to get rid of various accumulations of household waste; in this they are helped by a convenient, universal structure that gives away useful products instead of unnecessary ones.

Who operates the equipment

Small biogas plants are useful in modern rural households. Larger devices are used by serious cattle breeders, where it is impossible to exist without units that produce the necessary energy types.

The justification for installing it in the courtyard of a private house or large farm is the accumulation of organic matter, since any equipment needs power to work.

The world is fighting for the ecology of the environment, the most acceptable means for this is the construction of biogas facilities, they release pure substances and consume alternative fuels. On this basis, the devices have become in demand in farms in our country and abroad.

Standard equipment

Engineers assemble mechanisms of different sizes. Production depends on the required power, which the unit has to process and produce in exchange. A standard installation consists of the following components:

• storage tank, it receives material for processing
• mixers, mills that are structurally different from each other, they crush large raw material fragments
• gas holder, hermetically sealed, gas accumulates here
• reactor in the form of a reservoir where biofuel is formed
• devices supplying raw materials to the container
• installations that transfer the resulting fuel from one point to another for subsequent conversion
  automatic systems that protect and control the production process

The operation of the technological cycle has been worked out to the smallest detail to make it easier for a person to maintain the unit during the processing period.

How it works

The performance of the units is based on the principle of the influence of bacterial formations of various natures on organic matter, causing fermentation. These processes occur inside the reactor. From the decomposition of some products, another substance is obtained, its composition includes:

• methane
• carbon dioxide
• impurities of ammonia, hydrogen sulfide, nitrogen

The operating principle consists of the following steps:

• raw materials are supplied to the storage tank
• the material is broken up, moved by pumps and conveyors into the acid tank, in this tank the biomass is subjected to additional heating
• a durable, acid-resistant, tightly closed reactor receives prepared raw materials to create biogas

Devices are installed in the reactor to provide additional heating, within +40 degrees, mixing of substances, creating suitable conditions for them, accelerating the processes of decomposition and fermentation, from which the final product is formed. The processing speed depends on the capacity of the facility and the type of waste.

In progress:

• gas accumulation is carried out in gas tanks; they are mounted as a separate element or connected together with the housing
• The reactor tank collects, after the decomposition procedure is completed, it is transferred for use
• sufficient pressure is created in the gas tank tank to move the gas into the cleaning system, in this form it will be used by the consumer in various fields of activity
• used for their intended purpose, they acquire substances for fertilizers after separating them into their components in liquid or solid form and moving them to the storage part

The decision to begin construction must be accompanied by taking into account the conditions under which biogas plants operate with the required efficiency.

Basic options to choose from

Poor functionality of devices occurs due to poor planning. Errors may be noticed immediately or after some time. Through careful and comprehensive research, we ensure that equipment does not fail. The procedure begins after determining the availability of raw materials and how much energy is needed for the normal existence of energy resources.

The reactor and its dimensions are influenced by:

• amount of processing
• quality of material
• raw material type
• temperature regime
• fermentation period

In practice, in a particular farm, attention should be paid to the following points:

• daily loading of materials in relation to reactor size
• the volume of the container in which waste is processed
• calculate the output
• the ability to balance between the result and actual consumption

Before installing the equipment, you have to make a choice:

• the most optimal location for installation
• model suitable for design features

The main criteria that are relied upon when making a constructive choice are the location and definition of an underground or above-ground structure. In addition, when constructing the structure at the top, you should decide how to install the reactor in a vertical or horizontal position.

Biofertilizers are stored in buildings on the site or in pits and metal barrels. Costs will be reduced by ready-made parts of the installation, if they are available on the farm. The accumulation of materials determines the size and shape of the tanks in which they are mixed, as well as what kind of reactor and devices are needed for heating the substances, crushing them and mixing them.

The selected reactor design must comply with:

• practicality
• ease of maintenance
• gas- and water-tight to eliminate leaks and retain gas in full volume

A prerequisite for effective performance is the presence of high-quality thermal insulation. Construction costs and heat losses can be reduced by minimal surface areas.

The structure must be stable and withstand pressure loads:

• raw materials

The installations are equipped in the following most optimal forms:

• ovoid
• cylindrical
• conical
• semicircular

It is not recommended to equip square concrete or brick forms. The raw material puts pressure on the corners, causing cracks to appear, disrupting the processes occurring inside, and solid fragments accumulating. Materials ferment better and dried surfaces do not appear in structures with internal partitions.

The best materials for construction are:

• Steel - in these containers you can achieve absolute tightness, they are easy to manufacture, and they can withstand loads. The problem is increased susceptibility to corrosion. To prevent rust, surfaces are treated. If the farm has a metal tank, its quality should be checked from all sides. Get rid of shortcomings.
• Plastic - tanks made from this material are produced soft and hard. The first option is less suitable, since damage is easily caused and it is difficult to insulate. Tanks made of hard plastic are stable and do not rust.
• Concrete is used by some developing countries. They have no restrictions on service life; special coatings can prevent the appearance of cracks.
• Brick is used by India and China. For this, only well-fired products are used or walls made of concrete blocks or stone are laid.

When installing equipment made of concrete, brick or stone, it is necessary to take care of the internal fireproof finish that is resistant to organic matter and hydrogen sulfide.

The location of the structure should be taken with particular seriousness and the following factors should be taken into account:

• free space
• distance from housing
• storage
• location of cowsheds, pigsties, poultry houses
• groundwater
• convenient loading and unloading of materials

The reactors are located:

• on the surface with the foundation
• buried in the ground
• installed inside the farm

Devices operating using a chemical or biological reaction are equipped with hatches through which periodic repair work is carried out. The rubber gasket provides a seal when the lid is closed. Thermal insulation is necessary to carry out work regardless of the season.
The structure is insulated with improvised materials with layer-by-layer treatment of internal surfaces.

The technology is not new. It began to develop back in the 18th century, when Jan Helmont, a chemist, discovered that manure emits gases that are flammable.

His research was continued by Alessandro Volta and Humphrey Davy, who found methane in the gas mixture. At the end of the 19th century in England, biogas from manure was used in street lamps. In the mid-20th century, bacteria were discovered that produce methane and its precursors.

The fact is that three groups of microorganisms alternately work in manure, feeding on the waste products of previous bacteria.

The first to start working are acetogenic bacteria, which dissolve carbohydrates, proteins and fats in the slurry.

After processing the nutrient supply by anaerobic microorganisms, methane, water and carbon dioxide are formed. Due to the presence of water, biogas at this stage is not able to burn - it needs purification, so it is passed through treatment facilities.

What is biomethane

The gas obtained as a result of the decomposition of manure biomass is an analogue of natural gas. It is almost 2 times lighter than air, so it always rises. This explains the artificial production technology: free space is left at the top so that the substance can be released and accumulate, from where it is then pumped out for use for one’s own needs.

Methane greatly influences the greenhouse effect - much more than carbon dioxide - 21 times. Therefore, manure processing technology is not only an economical, but also an environmentally friendly way to dispose of animal waste.

• Biomethane is used for the following needs:

• cooking;

• in internal combustion engines of automobiles;

for heating a private house. Biogas produces a large amount of heat.

1 cubic meter is equivalent to burning 1.5 kg of coal.

How is biomethane produced?

It can be obtained not only from manure, but also algae, plant matter, fat and other animal waste, and residues from the processing of raw materials from fish shops. Depending on the quality of the source material and its energy capacity, the final yield of the gas mixture depends.

The minimum amount of gas obtained is 50 cubic meters per ton of cattle manure. Maximum - 1,300 cubic meters after processing animal fat. The methane content is up to 90%.

One type of biological gas is landfill gas. It is formed during the decomposition of garbage in suburban landfills. The West already has equipment that processes waste from the population and turns it into fuel. As a type of business, it has unlimited resources.

• Its raw material base includes:

• food industry;

• livestock farming;

• poultry farming;

• fisheries and processing plants;

• dairies;

Any industry is forced to dispose of its waste - it is expensive and unprofitable. At home, with the help of a small homemade installation, you can solve several problems at once: free heating of the house, fertilizing the land with high-quality nutrients left over from manure processing, freeing up space and eliminating odors.

Biofuel production technology

All bacteria that take part in the formation of biogas are anaerobic, that is, they do not need oxygen to function. To do this, completely sealed fermentation containers are constructed, the outlet pipes of which also do not allow air from the outside to pass through.

After pouring the raw liquid into the tank and raising the temperature to the required value, the bacteria begin to work. Methane begins to be released, which rises from the surface of the slurry. It is sent to special pillows or tanks, after which it is filtered and ends up in gas cylinders.

The liquid waste from bacteria accumulates at the bottom, from where it is periodically pumped out and also sent for storage. After this, a new portion of manure is pumped into the tank.

Temperature regime of bacteria functioning

To process manure into biogas, it is necessary to create suitable conditions for bacteria to work. some of them are activated at temperatures above 30 degrees - mesophilic. At the same time, the process is slower and the first products can be obtained after 2 weeks.

Thermophilic bacteria work at temperatures from 50 to 70 degrees. The time required to obtain biogas from manure is reduced to 3 days. In this case, the waste is a fermented sludge that is used in the fields as fertilizer for agricultural crops. There are no pathogenic microorganisms, helminths and weeds in the sludge, as they die when exposed to high temperatures.

There is a special type of thermophilic bacteria that can survive in an environment heated to 90 degrees. They are added to raw materials to speed up the fermentation process.

A decrease in temperature leads to a decrease in the activity of thermophilic or mesophilic bacteria. In private households, mesophylls are more often used, since they do not require special heating of the liquid and gas production is cheaper.

Subsequently, when the first batch of gas is received, it can be used to heat the reactor with thermophilic microorganisms.

How to prepare raw materials for pouring into the reactor

To produce biogas from manure, there is no need to specially introduce microorganisms into the liquid, because they are already found in animal excrement. You just need to maintain the temperature and add a new manure solution in time. It must be prepared correctly.

The humidity of the solution should be 90% (the consistency of liquid sour cream), Therefore, dry types of excrement are first filled with water - rabbit droppings, horse droppings, sheep droppings, goat droppings. Pig manure in its pure form does not need to be diluted, as it contains a lot of urine.

The next step is to break down the manure solids. The finer the fraction, the better the bacteria will process the mixture and the more gas will be released. For this purpose, the installations use a stirrer that is constantly running. It reduces the risk of a hard crust forming on the surface of the liquid.

Those types of manure that have the highest acidity are suitable for biogas production. They are also called cold - pork and cow. A decrease in acidity stops the activity of microorganisms, so it is necessary to monitor at the beginning how long it takes for them to completely process the volume of the tank. Then add the next dose.

Gas purification technology

When processing manure into biogas, the following is obtained:

• 70% methane;

• 30% carbon dioxide;

• 1% impurities of hydrogen sulfide and other volatile compounds.

In order for biogas to become suitable for use on the farm, it must be cleaned of impurities. To remove hydrogen sulfide, special filters are used. The fact is that volatile hydrogen sulfide compounds, dissolving in water, form acid. It contributes to the appearance of rust on the walls of pipes or tanks if they are made of metal.

• The resulting gas is compressed under a pressure of 9–11 atmospheres.

• It is fed into a reservoir of water, where impurities are dissolved in the liquid.

On an industrial scale, lime or activated carbon, as well as special filters, are used for cleaning.

How to reduce moisture content

There are several ways to get rid of water impurities in gas yourself. One of them is the principle of a moonshine still. The cold pipe directs the gas upward. The liquid condenses and flows down. To do this, the pipe is laid underground, where the temperature naturally decreases. As it rises, the temperature also rises, and the dried gas enters the storage facility.

The second option is a water seal. After exiting, the gas enters a container with water and is cleaned of impurities there. This method is called one-stage, when biogas is immediately cleaned from all volatile substances and moisture using water.

Water seal principle

What installations are used to produce biogas?

If the installation is planned to be located near a farm, then the best option would be a collapsible structure that can be easily transported to another location. The main element of the installation is a bioreactor into which raw materials are poured and the fermentation process occurs. Large enterprises use tanks volume 50 cubic meters.

In private farms, underground reservoirs are built as a bioreactor. They are laid out of brick in a prepared hole and coated with cement. Concrete increases the safety of the structure and prevents air from entering. The volume depends on how much raw material is obtained from domestic animals per day.

Surface systems are also popular at home. If desired, the installation can be disassembled and moved to another location, unlike a stationary underground reactor. Plastic, metal or polyvinyl chloride barrels are used as tanks.

By type of control there are:

• automatic stations in which the filling and pumping out of waste raw materials is carried out without human intervention;

• mechanical, where the entire process is controlled manually.

Using a pump, you can facilitate the emptying of the tank into which the waste after fermentation falls. Some craftsmen use pumps to pump gas from cushions (for example, car inner tubes) into a treatment facility.

Scheme of a homemade installation for producing biogas from manure

Before constructing a biogas plant on your site, you need to become familiar with the potential hazards that could cause the reactor to explode. The main condition is the absence of oxygen.

Methane is an explosive gas and can ignite, but to do so it must be heated above 500 degrees. If biogas mixes with air, overpressure will arise, which will rupture the reactor. Concrete may crack and will not be suitable for further use.

Video: Biogas from bird droppings

To prevent the pressure from tearing off the lid, use a counterweight, a protective gasket between the lid and the tank. The container is not completely filled - there should be at least 10% volume for gas release. Better - 20%.

So, to make a bioreactor with all the accessories on your site, you need to:

• It is good to choose a place so that it is located away from housing (you never know).

• Calculate the estimated amount of manure that animals produce daily. How to count - read below.

• Decide where to lay the loading and unloading pipes, as well as a pipe for condensing moisture in the resulting gas.

• Decide on the location of the waste tank (fertilizer by default).

• Dig a pit based on calculations of the amount of raw materials.

• Select a container that will serve as a reservoir for manure and install it in the pit. If a concrete reactor is planned, then the bottom of the pit is filled with concrete, the walls are lined with bricks and plastered with concrete mortar. After this, you need to give it time to dry.

• The connections between the reactor and the pipes are also sealed at the stage of laying the tank.

• Equip a hatch for inspection of the reactor. A sealed gasket is placed between it.

If the climate is cold, then before concreting or installing a plastic tank, consider ways to heat it. These can be heating devices or tape used in “warm floor” technology.

At the end of the work, check the reactor for leaks.

Gas quantity calculation

From one ton of manure you can get approximately 100 cubic meters of gas. Question: How much litter do pets produce per day?

• chicken – 165 g per day;

• cow – 35 kg;

• goat – 1 kg;

• horse – 15 kg;

• sheep – 1 kg;

• pig – 5 kg.

Multiply these figures by the number of heads and you get the daily dose of excrement to be processed.

More gas comes from cows and pigs. If you add energetically powerful plants such as corn, beet tops, and millet to the mixture, the amount of biogas will increase.

Marsh plants and algae have great potential. The highest is for waste from meat processing plants. If there are such farms nearby, then we can cooperate and install one reactor for everyone.

The payback period for a bioreactor is 1–2 years.

Biomass waste after gas production

After processing manure in a reactor, the by-product is biosludge. During anaerobic processing of waste, bacteria dissolve about 30% of organic matter. The rest is released unchanged.

The liquid substance is also a by-product of methane fermentation and is also used in agriculture for root feeding. Carbon dioxide is a waste fraction that biogas producers strive to remove.

But if you dissolve it in water, then this liquid can also be beneficial.

In order to completely utilize the products obtained after processing manure, it is necessary to maintain a greenhouse. Firstly, organic fertilizer can be used for year-round cultivation of vegetables, the yield of which will be stable.

Secondly, carbon dioxide is used as fertilizing - root or foliar, and its output is about 30%. Plants absorb carbon dioxide from the air and at the same time grow better and gain green mass. If you consult with specialists in this field, they will help you install equipment that converts carbon dioxide from liquid form into a volatile substance.

Video: Biogas in 2 days

The fact is that to maintain a livestock farm, the energy resources obtained can be a lot, especially in the summer, when heating the barn or pigsty is not needed.

Therefore, it is recommended to engage in another profitable activity - an environmentally friendly greenhouse. Remaining products can be stored in refrigerated rooms - using the same energy. Refrigeration or any other equipment can run on electricity generated by a gas battery.

Use as fertilizer

In addition to producing gas, the bioreactor is useful because the waste is used as a valuable fertilizer, which retains almost all nitrogen and phosphates. When manure is added to the soil, 30–40% of nitrogen is irretrievably lost.

To reduce the loss of nitrogen substances, fresh excrement is added to the soil, but then the released methane damages the root system of plants. After processing the manure, the methane is used for its own needs, and all nutrients are preserved.

After fermentation, potassium and phosphorus pass into a chelated form, which is absorbed by plants by 90%. If you look at it in general, then 1 ton of fermented manure can replace 70 - 80 tons of ordinary animal excrement.

Anaerobic processing preserves all the nitrogen present in manure, converting it into ammonium form, which increases the yield of any crop by 20%.

This substance is not dangerous for the root system and can be applied 2 weeks before planting crops in open ground, so that the organic matter has time to be processed by soil aerobic microorganisms.

Before use, the biofertilizer is diluted with water. in a ratio of 1:60. Both dry and liquid fractions are suitable for this, which after fermentation also goes into the waste raw material tank.

Per hectare you need from 700 to 1,000 kg/l of undiluted fertilizer. Considering that from one cubic meter of reactor area up to 40 kg of fertilizers are obtained per day, in a month you can provide not only your own plot, but also your neighbor’s, by selling organic matter.

What nutrients can be obtained after manure processing?

The main value of fermented manure as a fertilizer is the presence of humic acids, which, like a shell, retain potassium and phosphorus ions. Oxidizing in air during long-term storage, microelements lose their beneficial qualities, but during anaerobic processing, on the contrary, they gain.

Humates have a positive effect on the physical and chemical composition of the soil. As a result of adding organic matter, even the heaviest soils become more permeable to moisture. In addition, organic matter provides food for soil bacteria. They further process the residues that have not been eaten by anaerobes and release humic acids. As a result of this process, plants receive nutrients that are completely absorbed.

In addition to the main ones - nitrogen, potassium and phosphorus - the biofertilizer contains microelements. But their quantity depends on the source material - plant or animal origin.

Sludge storage methods

It is best to store fermented manure dry. This makes it more convenient to pack and transport. The dry substance loses less useful properties and can be stored closed. Although such fertilizer does not deteriorate at all over the course of a year, it must then be sealed in a bag or container.

Liquid forms must be stored in closed containers with a tight-fitting lid to prevent nitrogen from escaping.

The main problem of biofertilizer producers is marketing in winter, when plants are dormant. On the world market, the cost of fertilizers of this quality fluctuates around $130 per ton. If you set up a line for packaging concentrates, you can pay for your reactor within two years.

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The production of biogas (methane) is important for owners of livestock and poultry breeding farms. On farms with poultry and cattle, the issue of waste disposal is always acute. In order to get rid of litter and manure, you need to take care of collection, removal, disinfection and processing. All these procedures require certain material expenditures, time and effort.

In order for the manure recycling process to begin to bring profit rather than losses, it is advisable to think about processing manure into biogas. Homemade biogas from bird and animal droppings consists of 50-80% methane. This is the same gas that burns in boilers, stoves and is used for cars. Methane is released from manure randomly, on its own. If you leave droppings to rot in the sun for a year, it will begin to “ferment” and release biogas. You just need to optimize this process to increase the amount of methane released and speed up its production time.

To increase the efficiency of biogas production, it is necessary to accelerate the process of decomposition and fermentation of raw materials. To do this, you need to create the most favorable conditions for the proliferation of the necessary bacteria. To do this, you will need to place the manure in a special container - a reactor. The container must be closed - in such conditions bacteria will multiply more actively. Already in the reactor, the manure is crushed and then mixed with water. The water must be clean. Otherwise, foreign microbes will enter the substrate, which can slow down the fermentation process.

In industrial conditions, it is equipped with a reactor heating system, an acidity controller and special blades for mixing the substrate. Mixing manure allows you to get rid of the formation of a hard crust, which blocks the flow of oxygen from the outside and the release of methane from the inside. The period for producing methane under industrial conditions is at least fifteen days. During this time, manure can decompose up to 25%. The maximum outflow of methane occurs at a degree of decomposition of 33%.

It should be taken into account that rotten sludge forms at the bottom of the reactor. It is discharged using a special tube, which takes it to a separate sludge tank. The sludge is subsequently cleaned out and removed. The methane rising up the tank is purified by a steam bath, and then sent to the gas collector.

Industrial methane production involves daily injection of fresh substrate, which is mixed with what has already begun to ferment. You can add 5% fresh manure per day instead of 5% used manure. Manure removed from the reactor can be used as soil fertilizer. This way you will have a waste-free production, where you can get both biogas and fertilizers.

Creating a biogas plant from manure at home

To design a plant for processing manure into biogas you will need:

• a hermetically sealed container (made of metal, concrete, plastic) with a volume of at least one cubic meter;
• cover for the reactor with a sealed passage for the stirrer handle;
• material for thermal insulation of the bottom (plays the role of a heating system);
• a hand mixer made from scrap materials (you can use a shovel or a screw auger);
• pipes for feeding/extracting substrate and for removing biogas.

During the construction process, you may need additional materials: pipes, filters, valves. All this can be found at a hardware store. The design is quite simple, and you can improve it as you build it.

As an experiment, you can try making an installation from an ordinary plastic barrel. They are available in volumes from 100 to 200 liters. The barrel will serve as a reactor. Make two holes in it for the inlet and outlet of the pipes. The inlet hole is made closer to the bottom, and the outlet hole is made from above. The diameter of the holes depends on the diameter of the pipes used. Plastic pipes can be purchased at a hardware store. We insert them into the holes and securely insulate them. A curved pipe (with a connector) is suitable for the inlet, and a short straight pipe for the outlet.

The role of a reservoir for the resulting biogas is given to a container of a smaller volume. For example, you can take a bucket with a volume of 20 liters or more. The bucket is fixed using a plumbing valve. We take the tube from it to a metal holder with a valve, from where the gas will be released.

Don't forget about the thermal insulation of the barrel. It can be wrapped with mineral wool, polyethylene foam or any other material. It is best to place the barrel in the sun to increase the temperature inside the reactor. We pour raw materials inside in a ratio of 0.7 liters of water per 1 kg of manure. We put any suitable container for removing sludge, place a bucket on top and wait for fermentation. We are waiting about three weeks for the first batch of our home biogas. Remember that methane must be stripped of carbon dioxide before use. A special filter, which is sold in the store as a “filter for purifying compressed air, carbon dioxide and steam,” will cope with this task.

Do-it-yourself biogas from manure: building an underground installation

Another easy way to build your own manure-to-biogas plant is to build an underground system. First you need to dig a hole with a volume of at least one cubic meter. Its walls and bottom are filled with expanded clay concrete. From opposite walls there is one pipe for supplying biomass and removing sludge. The outlet pipe should be located closer to the bottom, and the input pipe should be 50 cm above the bottom. The end of the outlet pipe is connected to a waste container. The end of the inlet pipe should be located in such a way that it is convenient for you to pump new raw materials through it.

The upper part of this “bunker” is a dome- or cone-shaped gas holder. It is easiest to make from metal sheets or brickwork. A sealed hatch and a gas pipe with a water seal are mounted on the top of the gas holder. We advise you to provide such an important detail as a pressure relief valve. It will ensure safety when working with the installation and will maintain optimal pressure inside the reactor.

Mixing of the substrate in such an installation occurs according to the bubbling principle. To do this, take several plastic pipes and make as many holes in them as possible. After this, secure the pipes inside the reactor in a vertical position. When the gas rises, it will emit bubbles, which will begin to bubble in the substrate, thereby mixing it.

Biogas from manure is a profitable investment

For those who are not ready to make such a camera, there is always another option - you can buy a ready-made one. Construction of the installation will still require a small investment from you. If you are not confident in your abilities or do not have all the materials, it is advisable to simply buy a PVC installation. As a result, you will still organize your own home production for processing manure and producing biogas.

The growing popularity of alternative methods for generating heat and electrical energy has led to the desire of many owners of country houses and cottages to gain a certain autonomy from external energy suppliers. Moreover, “purchased” energy shows a constant tendency to increase prices, and the maintenance of a country farm is becoming more and more expensive every day. The biogas plant is an excellent alternative to external energy sources. At a minimum, it can provide the house with flammable gas for the stove, and when the power increases (if there is enough of your own or purchased waste), it can provide both heating and electricity for both the house and the entire household.

Who needs biogas plants

Biogas plants are used to produce combustible gases from biological raw materials. So they are needed wherever flammable gases are required. That is, to obtain thermal and electrical energy.
First of all, biogas plants are necessary for those farms where there is a lot of raw materials in the form of biological waste. In this way, it is possible not only to make production waste-free, but also to significantly increase its profitability - due to independent energy production and the absence of costs for the purchase of both thermal and electrical energy.

Vladimir Rashin, a designer of a biogas plant and a farmer from Perm, has proven from his own experience that agricultural production, which independently disposes of waste using an appropriate device, fully meets its needs for thermal and electrical energy, as well as combustible gas. In his quail farm, biogas is used to heat premises (both residential, utility and industrial), to generate electricity, in kitchen stoves, and also to refuel vehicles - all cars on the Rashin farm run on biogas. In this case, the main raw material for the biogas plant is quail droppings. The output, in addition to biogas, also produces organic fertilizer, which also brings additional income to the farm.

Biogas plants like Vladimir Rashin's can significantly increase the profitability of any agricultural production. Not only manure, but also various waste from wood processing industries (bark, sawdust, etc.), and almost any organic substances can be used as a raw material for producing biogas.

In addition, biogas plants can be used in country houses and cottages, even if such farms do not have a farming focus. The household waste of any farm will be enough to provide raw materials for an individual biogas plant, and if the farm is not fully provided with thermal and electrical energy, then at least reduce the cost of purchasing such energy. In addition, in addition to household waste, any country farm also contains waste from the plot (weeds, branch cuttings, and so on). Well, you can even provide a kitchen stove with flammable gas using a mini-biogas installation in a country house.

Principle of biogas production

Biogas is produced by anaerobic (that is, without oxygen) fermentation of biomass, which is provided by special bacteria. Three types of bacteria are involved in the process: hydrolytic, acid-forming and methane-forming.

A biogas plant consists of several parts (containers). First, the raw material enters a preliminary container, where it is thoroughly mixed and crushed (in the case of the solid fraction) to a homogeneous mass. Then the crushed raw material enters the reactor (a container where the biomass is directly fermented).

The reactor is usually made of reinforced concrete, which is acid-resistant. This container is completely sealed. In order to speed up the fermentation process, the liquid in the container is heated and stirred. Most often, a cogeneration unit is used to heat the reactor - in such an installation it is necessary to cool the heat and power generator, and the removed heat enters the reactor. Heat can also come from a special hot water boiler.

After the fermentation process is completed, the produced gas from the reactor enters the gas holder, where the pressure is equalized, and then the biogas enters the heat and power generator (gas or diesel-gas), as a result of which thermal or electrical energy is produced.

In addition to biogas, a solid fraction—organic fertilizers—settles in the reactor, which can then be used in the fields. Liquid fertilizers are also obtained from the reactor after gas is released. Both liquid and solid fertilizers are concentrated and are actively used in agriculture.

Industrial biogas plants have automatic control. Automation is responsible for the flow of raw materials into the installation, and for mixing, controls the temperature, the operation of the generator, and so on. Also, such installations are equipped with emergency flare devices - in case the engine stops, then the gas is simply burned. In addition, industrial biogas plants are often equipped with a line for packaging liquid fertilizers; in this case, the fertilizers are bottled in small (up to 1 liter) bottles.

Individual biogas plant

The operating principle of an individual biogas plant is the same as that of an industrial one. True, mini-installations are rarely equipped with automatic devices for mixing the substrate and other automation - due to the significant increase in the cost of a household installation with such equipment. Most often, these installations only have devices for controlling temperature, generator operation, and so on, and all maintenance of the mini-biogas plant is carried out manually.

Household biogas plants are used mainly for the production of combustible gas for kitchen needs, if the farm does not have livestock or crop production. However, there is an increasing tendency to use mini-installations to provide country houses and cottages with a complete energy complex, that is, not only “kitchen” gas, but also thermal and electrical energy. Moreover, this no longer depends on the presence of large or small livestock on the farm; raw materials for home biogas plants are simply purchased from the nearest farm. This can be either manure or waste from wood processing industries.

DIY biogas plant

The construction of biogas plants, even mini ones, for domestic needs, is not cheap. And, although the payback period for such equipment is relatively short (5-7 years), not every owner is ready or has the opportunity to invest the required amount. Yes, the advantages are obvious: in a short time, with the help of a mini-biogas plant, you can gain almost complete autonomy from purchased energy sources, transfer your farm to self-sufficiency, and even have free fertilizers as additional bonuses. However, you need to pay money today, and the benefits will only appear in a few years. Therefore, many owners of country houses and cottages are wondering: how to make a biogas plant yourself?

A mini biogas plant is not that complicated, and its construction is quite manageable. This saves a significant amount. In addition, there are projects for biogas plants that use improvised means and materials (for example, with a bell reactor, and the bell can be made of rubber, and so on). That is, homemade installations for the production of biogas mean acquiring the desired bonuses for minimal money.

When building a biogas plant, it is necessary to make an accurate calculation of what its productivity should be. To do this, you should take into account all the desired consumers of biogas (for example, a cooker, automotive equipment, and so on). If biogas is planned to be used to produce electrical and/or thermal energy, then the calculation must include all energy consumers. Based on the calculation, a biogas plant project is created.

Homemade biogas production plants are widely available on the Internet. You can find sample calculations, a drawing of the device, and a detailed description. A huge selection of devices will allow you to create both a complex installation with several chambers and a simplified version (for example, such a simple device as a cesspool covered with a rubber bell with a device for venting gas). Anyone can choose a home-made installation in accordance with their desires, capabilities and skills. Descriptions accompanied by step-by-step photographs or videos are especially useful in this case.

Making a biogas plant with your own hands allows you to save up to 50% of the cost of the device, which significantly speeds up the payback of the equipment. In addition, making the simplest installation to begin with allows you to assess the need for such equipment in the household, as well as invest money gradually, which for many is much easier than paying the entire required amount at once.

How does a biogas plant work?