Biogas can be produced in digesters. Production depends on the following factors: Organic content, Wet or dry waste, Land availability. There are several different types of digester technologies including lagoons which are typically employed when the feedstock is wastewater effluent from agricultural waste or animal manure. Using this technology, typical retention time of material is between 30 and 40 days for the biogas to reach full production. A lagoon is a good option when sufficient land is available.
Other technologies such as Continuously Stirred Tank Reactors (CSTR) and Dry Cell Anaerobic Digestion (DCAD) are used when land requirements are limited. CSTR’s are a proven and reliable technology as an alternative to a lagoon based system but are slightly more expensive to build than a lagoon, and require more attention during operation.