biodigesterbi·o·di·gest·er /ˌbaɪəʊdaɪˈdʒestə, -də- $ -oʊdaɪˈdʒestər, -də-/ noun [countable] 
a large container in which plant material or animal waste is changed by bacteria, producing methaneand carbon dioxide
a large container in which plant material or animal waste is changed by bacteria, producing methaneand carbon dioxide