Abstract
In the following study, a two‐phase anaerobic digestion with an optimised hydrolysis‐acidification reactor was studied in comparison with a single‐step digestion of municipal mixed sludge. The results of the two processes were compared by using the statistical test of BEHRENS‐FISHER. The advantages of the two‐phase digester were the following : ‐Faster steady‐state conditions, they were reached after 45 days instead of 75 days for the single‐stage process. ‐ Greater elimination of volatile suspended solids (degradacion of 60 % instead of 40 %). ‐ Decrease of the retention time by a factor two (11,6 days instead of 25 days).