Fig. 4
From: Methanogens: biochemical background and biotechnological applications
Micro biogas systems. a Arti biogas (India). Material two plastic water tanks (working volume of 1 m3). Substrate mainly kitchen waste. Disadvantage of gas losses of up to 20% (Voegeli et al. 2009). b Floating cover (India). Material bricks and metal cover. Top rises when gas is produced. Substrate mainly pig and cow manure (Bond and Templeton 2011). c Fixed dome (China). Material bricks and clay. Substrate mainly pig and cow manure (Plöchl and Heiermann 2006). d Plug flow. Material affordable plastic foils (Bond and Templeton 2011)