In the first phase, protein, carbohydrate and fat are converted to soluble substances followed by acid formation
give rise to fatty acids, amino acids and alcohols by acidogenic bacteria. Methane, carbon dioxide, hydrogen
sulphide and ammonia form in the third phase by methanogenic bacteria. The slurry becomes somewhat
thinner during the process of digestion [12]. The more the two phases merge the shorter the digestion times. The
conditions for this are particularly favorable in the “fermentation channel” arrangement. The following types of
digestion are distinguished according to the temperature in the digester: