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Standard Process of Biogas Production

In the standard process of biogas production for Didask Bioenergy plants, the bioorganic material or substrate is processed before being fed into the biogas plant. The plant consists of a receiving tank, a pump or screw feeder, two digesters with mixing and heating devices and a gas storage tank. A desulphurization reactor along with a gas drier is added to make the gas free of sulphur and water vapors.

The digesters are also called fermentation tanks and are the crucial components of the plant since they provide the anaerobic conditions in which the bacteria generate biogas. The substrates have to be constantly heated and stirred in order to ensure their homogeneity and the consistent discharge of gas. The gas holder is normally an airproof steel container that, by floating like an upturned vessel on the fermentation mix, cuts off air to the digesters and collects the gas generated in the upturned vessel. Each plant at Didask Bioenergy is uniquely designed, however the most widely used designs have the gas holder equipped with a gas outlet, while the digesters are provided with an overflow pipe to lead the digestate out into a fertilizer storage area.

Substrate fed to the receiving tank

Animal Dung or manure is pumped directly from a receiving tank into the digesters. To generate significantly more methane than manure alone, Didask Bioenergy digesters accept multiple substrates, from grease to corn silage to food waste. Manure has low energy content since the cattle has already digested the substrate, so adding high-energy value materials produces more methane gas. The complete & continuous mix action in absence of oxygen within the digesters sustains an optimal environment for bacteria to digest these high-energy materials. A pump or screw conveyor feeds the raw materials into the digesters, and other necessary equipment such as grinders are incorporated into the facility wherever required. Automated feeding regulates input of material to ensure optimal digestion and thus optimal production of biogas and reduces labor required for operating the plant.

The Digesters

A Didask biogas facility typically has two or more cylindrical digesters with heating pipes integrated into the walls and floor. The walls are insulated and clad with thermal panels. The digesters are built at ground level to reduce costs and facilitate maintenance, and their cylindrical shape ensures maximum engineering and thermal soundness. With two or more digesters, several crucial benefits are achieved over a single tank design.
In Didask Bioenergy plants, if one digester is taken offline, the other continues to operate without interruption, so the Biogas farmer is not stuck with tons of raw substrate to deal with. Another reason for multiple digesters is the ease of expansion. In order to increase facility capacity by any amount, a digester can be added at any time. Quick disaster prevention and recovery is also a reason for adding additional reactors. If the bacteria in one digester get sick, healthy bacteria from the other tanks can be added to bring it back to normalcy without much delay.

Mixing devices

In Didask Bioenergy plants, the contents of each tank are mixed with two to four submerged agitators to foster optimal bacterial proliferation and ensure steady, reliable methane production. The agitators adjust automatically or manually and ensure a complete, pervasive mix of substrate for an optimized climate for bacterial proliferation and pathogen treatment. Agitators have an expected lifetime of 8-10 years since they only run for 5-20 minutes each hour. Should an agitator require repair or replacement, it's simply matter of folding back the roof, lifting out the unit, and replacing it in minutes. Unlike digesters with concrete roofs or central mixing devices, there is minimal downtime and no loss of operations.

Gas Storage System

Inside the digester, biogas is formed in fluctuating quantities and with performance peaks. Biogas production must be maintained as stable and constant as possible. When biogas is consumed, there would be a large variation in the pressure. To compensate for this variation, it is necessary to temporarily store the produced biogas, in appropriate storage facilities. Various types of biogas storage facilities are available today. The simplest solution is the biogas storage established on top of digesters, using a gas tight membrane, which has also functions as a digester cover. For larger biogas plants, separate biogas storage facilities are established, usually as stand-alone facilities. The biogas storage facilities can be operated at low, medium or high pressure.
Correct selection and dimensioning of biogas storage facility brings substantial contribution to the efficiency, reliability and safety of the biogas plant while ensuring constant supply of biogas and minimizing losses of biogas.
All biogas storage facilities are gas tight and pressure-resistant, and in case of storage facilities which are not protected by buildings, they are UV-, temperature- and weather proof. Before starting-up the biogas plant, the gas storage tanks must be checked for gas tightness. For safety reasons, Didask bioenergy plants are equipped with safety valves for under-pressure and over-pressure monitoring, to prevent damages and safety risks. Explosion protection systems and an emergency flare are also provided. The gas storage facility provided has a minimum capacity corresponding to one fourth of the daily biogas production. Normally, a capacity of one or two day’s gas production is recommended. Gas storage is provided as standard equipment, which gives considerable energy production efficiencies. For example, when the CHP unit is turned off for routine maintenance, the gas can be stored until operations continue. That way, customers don't lose a cubic foot of methane to flaring. Every minute of gas flared is money lost so gas storage adds directly to the bottom line.


High levels of hydrogen sulphide reaching the Combined Heat and Power unit cause severe degradation of the machinery and lead to recurring mechanical failures. Didask Bioenergy builds desulphurization equipment into the digesters that can reduce hydrogen sulphide to acceptable levels, depending on substrates, and can add additional equipment as required. Didask Bioenergys desulphurization is well within the acceptable range for CHP units. For those facilities that require further reduction of sulphur content, additional desulphurization systems are provided.

Combined heat and power unit

After desulphurization, the biogas is converted into electrical and thermal energy in a combined heat and power (CHP) unit. All of the facility's equipment, including the digester heating, runs on power generated by the CHP unit. Surplus electricity which amounts to typically 95% of the volume generated can be fed into the public grid and sold to the local power utility. Surplus heat can be used to heat or cool homes or buildings as well as for agricultural and industrial processes that require significant heat.


To make the world a better place to live in by the development of economic, efficient and environmental friendly energy technology solutions.


To create environmental sustainability and energy independence through the growth of the biogas industry thus reducing the dependence n fossil fuels.


Biogas is the one of the only technologically fully established

renewable energy source that is capable of producing heat, steam, electricity, vehicle fuel and other valuable byproducts. It is, in the true sense of the word, a dynamic energy source. Biogas has become a fuel to be looked forward to. This growth has begun over the last two decades.

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