Anaerobic digestion has a number of significant advantages as a method for treating sludge. One of the most significant is the potential for energy recovery and re-use. In a properly heated and mixed anaerobic digester, the balance between acid-producing and methane-producing microbes becomes optimal for the production of methane as a byproduct.

In most cases, the methane produced by the digester is well-concentrated. Because methane is the principal component of natural gas (usually on the range of about 75%), it is an excellent source of energy for use either in cogeneration on the electrical grid or simply for fueling boilers at the wastewater treatment plant.

The methane captured from an anaerobic digester will naturally contain some impurities, chiefly sulfur, which should be scrubbed prior to pressurization and combustion in order to protect the boiler elements. However, when performed effectively within a well-balanced anaerobic digester, methane recovery can be highly efficient and will often pay back the cost of the capital equipment involved in a matter of just a few years. Methane recovery can work for mechanical plants and solid-waste landfills as well as some lagoon treatment systems.

Wastewater treatment plants are heavy users of energy, and the use of methane recovery within anaerobic digesters can make the plant a net producer of energy rather than a consumer. For many municipalities as well as waste-intensive industries, methane recovery and energy generation from anaerobic digestion should be considered as an environmentally-friendly option for reducing solid wastes, improving wastewater treatment, and reducing energy costs.

Natural gas prices are volatile and are forecast to increase significantly in the near future. For more information on energy recovery through anaerobic digestion, contact us for design assistance and we'll be happy to assist you.

last revised 10.12.2005