The SS was collected from the wastewater treatment plant of
Kazan city (Tatarstan Republic, Russia) and the OFMSW was collected
from the waste sorting station of Kazan city (Tatarstan
Republic, Russia).
The SS and OFMSW were mixed in a 2:1 w/w ratio. Each of the
waste types individually and their mixtures were divided into two
parts. The first part was anaerobically digested by the addition of
10% inoculate (a fermentative mass after a previous digestion).
Anaerobic digestion for each sample was performed in 3 hermetically
sealed 12 L vessels at 55.5 C and fermentation was performed
for 15 days. After 15 days of fermentation, the digestate
was dehydrated to a moisture content of 80% and was mixed with
oiled sawdust (OS) in a 5:2 w/w ratio, and was further composted
in a mesophilic regime for 90 days. The size of the composting piles
was 0.03 m3. The second parts of the wastes fractions and their
mixtures were also mixed with OS and composted. Digestion process
for each variant was carried out in triplicate. Composting process
was carried out in one pile for each variant. During the
anaerobic digestion the samples were taken at the beginning and
at the end of the process. The wastes and digestates were collected
from 5 sampling points and then mixed. During the composting
the samples (from 5 sampling points) were taken at the beginning
and after 30, 60 and 90 days of the composting.