A digester is a sealed chamber (ECOFOCUS´S models adopted) where organic matter diluted with water undergoes a process of anaerobic fermentation (without presence of oxygen), which results in the production of a liquid effluent of high fertilizing power (biofertilizer) and gas methane (biogas).

Can be made with solid bricks or mortar (ferrocement). The use raises a number of economic and environmental advantages, not only as secure treatment of sewage, but also in energy production that can be used to illuminate or cooking. Also, if treated properly, resulting in an effluent which can be used in organic farming.