The use of a source high in anaerobic microbes (digester effluent for example) to start up an anaerobic system is called inoculation. According to Wilkie (2008), the quality and quantity of inoculums are critical to the performance, time required, and stability of biomethanogenesis during commissioning (startup) or restart of an anaerobic digester. In manures and some wastes the microbes needed for digestion may be already present in the waste in small numbers, albeit sufficient to act as inoculums, and will develop into a fully functional bacterial population if the right conditions are provided (Wilkie 2008).