Description of a Biogas Power Plant

A biogas plant is a decentralized energy system, which can lead to self-sufficiency in heat and power needs, and at the same time reduces environmental pollution. The components of a modern biogas (or anaerobic digestion) plant include: manure collection, anaerobic digester, effluent treatment, gas storage, and gas use/electricity generating equipment. The fresh animal manure is stored in a collection tank before its processing to the homogenization tank which is equipped with a mixer to facilitate homogenization of the waste stream. The uniformly mixed waste is passed through a macerator to obtain uniform particle size of 5-10 mm and pumped into suitable-capacity anaerobic digesters where stabilization of organic waste takes place.

In anaerobic digestion, organic material is converted to biogas by a series of bacteria groups into methane and carbon dioxide. The majority of commercially operating digesters are plug flow and complete-mix reactors operating at mesophilic temperatures. The type of digester used varies with the consistency and solids content of the feedstock, with capital investment factors and with the primary purpose of digestion.

Biogas contain significant amount of hydrogen sulfide (H2S) gas which needs to be stripped off due to its highly corrosive nature. The removal of H2S takes place in a biological desulphurization unit in which a limited quantity of air is added to biogas in the presence of specialized aerobic bacteria which oxidizes H2S into elemental sulfur.

Gas is dried and vented into a CHP unit to a generator to produce electricity and heat. The size of the CHP system depends on the amount of biogas produced daily. The digested substrate is passed through screw presses for dewatering and then subjected to solar drying and conditioning to give high-quality organic fertilizer. The press water is treated in an effluent treatment plant based on activated sludge process which consists of an aeration tank and a secondary clarifier. The treated wastewater is recycled to meet in-house plant requirements. A chemical laboratory is necessary to continuously monitor important environmental parameters such as BOD, COD, VFA, pH, ammonia, C:N ratio at different locations for efficient and proper functioning of the process.

The continuous monitoring of the biogas plant is achieved by using a remote control system such as Supervisory Control and Data Acquisition (SCADA) system. This remote system facilitates immediate feedback and adjustment, which can result in energy savings.

About Salman Zafar

Salman Zafar is a renowned expert in waste management, biomass energy, waste-to-energy and sustainable development. He is proactively engaged in creating mass awareness on renewable energy, waste management and environment. Salman is the CEO of BioEnergy Consult, apart from being the Founder of Cleantech Solutions and EcoMENA. Salman has successfully accomplished a wide range of projects in the areas of biogas technology, biomass energy, waste-to-energy and solid waste management. He has participated in numerous national and international conferences and has authored many articles in reputed journals and magazines. Salman can be reached at salman@bioenergyconsult.com or salman@cleantechloops.com.
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One Response to Description of a Biogas Power Plant

  1. Uncle B says:

    Canadians have run cars and trucks for decades on CNG 9Compressed Natural Gas) and methane form Anaerobic digestion – gas is stored in common “propane tanks” works just fine!
    In this very cold and “Heat Concious” country, we would rather pipe gas to the point of use, and enjoy the heat as well as the service rendered! Honda sells a home heating/ electricity generating plant for Canada. Germany has done this for years. Austerity and plain Canadian frugality demands the very cheapest smartest solution at all times – unlike our American cousins we cannot bear waste of any kind. Ontario dairy farms currently and commonly “poop-powered” most the heat and electricity locally generated.
    Good on you for finally putting sewage to a better use than polluting your own drinking water!

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