For all of the treatments, firstly, PP and CM were mixed together
in accordance to their fractions, and then, tap water was added so that the water content
in the digester reached the desirable content, 93 %. In Table 1, the wet weight, C:N ratio,
and the added water of the mixtures are shown. The C:N ratio between 12.5 and 24.4 is
suitable for AD conditions [18]. The pH value for all of the treatments was reached to a
desirable amount (7.6), at the beginning of the process, by adding sodium bicarbonate
solution (10 % concentration) [19]. The substrates were charged into the reactor, and the
lid was tightly closed. To assure anaerobic conditions, the head space of the reactor was
purged with helium gas for about 5 min prior to starting the digestion tests. During the