The biogas yield of each experiment was measured by
fermentation tests (triplicate determination). Therefore, ca.
20 g of aqueous chicken manure mixture together with 200 g
of digested sludge were filled in gas proofed batch reactor
and stirred with 110 rpm at 38 C under nitrogen atmosphere
(anaerobic milieu). The produced amount of gas was detected
by eudiometers one time a day and the methane content
by a gas analyzer (COMBIMASS GA-m, Binder, Ulm
(Germany)).