composting plant in Manresa (Barcelona, Spain). All the composting
experiments with the three wastes considered (MSW, OF_wood
and OF_tube) were carried out with aliquots of 25 kg per reactor
and performed in duplicate.
Air-filled porosity was determined using an air pycnometer
according to previous studies (specific details about the methodology
can be found in Ruggieri et al., 2009). The results of air-filled
porosity for OF_wood and OF_tube, mixed in the laboratory, initial
MSW (not mixed, the waste collected was composted as collected
from the plant) and final samples for the six trials can be found in
Table 1. A homogeneous sample from each waste and each mixture
(waste plus bulking agent) was stored at 18 C to be used for
waste characterization.
The main characteristics of the initial wastes and the final products
obtained from each experiment are presented in Table 1. Dry
and organic matter, conductivity and pH have been determined in
triplicate following the standard procedures for composting samples
(US Department of Agriculture and US Composting Council,
2001).