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 key components of a modern biogas power (or anaerobic digestion) plant include: manure collection, anaerobic digester, effluent treatment, biogas storage, and biogas use/electricity generating equipment.
Working of a Biogas Plant
The fresh organic waste 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 digester 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 Cleanup
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.
Utilization of Biogas
Biogas 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.
Treatment of Digestate
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.
Monitoring of Environmental Parameters
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.
Control System
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.
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!
Dear Salman,
We are an international EPC who does alot on the construction. We are capable of EPCC and also a developers.
WE are looking at green energy and is there any new projects taking place in Malaysia which can participate.
Regards,
Mohan
There is an availability of 250 ton cow dung every day. How the commercial power plant can be run from that ? What would be the outcome of energy from approx 250 ton cow dung & what would be the approx project cost ?
One more thing is that what is the best usage of different kind of waste outcome from a city to dispose off the same ?
Dear Rupin
Thanks for your comment.
A biogas plant based on 250 tpd of cowdung will produce atleast 10000 m3 of biogas. Each m3 of biogas will give around 2kWh of usable electricity.
Best wishes
Salman Zafar
salman@bioenergyconsult.com