Anaerobic Digester (AD) can be performed using wet and dry processes.
In the wet AD process, AD operates in a similar process to a digestive tract. De-packaged food slurry is fed into large steel digester tanks full of bacteria, which break down the organic waste to produce methane and digestate. The methane is burned in engines to produce electricity (and heat, where the latter has an economic use). The digestate is dewatered where possible and treated to become a fertiliser, while the water is cleaned and discharged.
In the dry AD process, anearoic bacteria is used to produce biogas. Organic materials are sealed inside anaerobic digestion tunnels fitted with airtight doors.