## 3 Results and Discussion
### Evolution of Soluble and Polymeric Fractions  
In a composting process, the decomposition of polymeric residual matter occurs through microbial action. The microbiota consume nutrients in chemical forms solubilized and simple. If this is not the case, the nutrients must be biotransformed into metabolizable compounds. The exoenzymes secreted by the microorganisms produce the release of the basic sources of nutrients. This action allows the growth of the composing microbiome. Therefore, during composting there must be considerable consumption of the soluble \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Facility \({}^{**}\)**} & \multirow{2}{*}{**M (\%)**} & \multirow{2}{*}{**pH**} & \multicolumn{2}{c}{**EC**} & \multirow{2}{*}{**OM (\%)**} & \multicolumn{2}{c}{**AT\({}_{\mathbf{4}}\)**} & \multicolumn{2}{c}{**DRI**} & \multirow{2}{*}{**GI (\%)**} \\  & & & & & & **(gO\({}_{2}\) kg\({}^{-1}\) OM)** & & & \\ \hline
**VR1** & 85.94 d & 8.10 ef & 16.78 c & 74.06 de & 12.63 d & 52.38 a & 1.07 ab & 7.70 ab \\
**VR2** & 66.62 b & 8.04 ef & 14.73 cd & 73.48 d & 13.30 d & 67.03 a & 1.70 b & 0.00 a \\
**VR3** & 29.27 a & 6.78 c & 13.53 d & 77.13 f & 10.61 c & 38.98 a & 0.46 a & 1.91 b \\
**MSW1** & 78.19 c & 5.16 b & 3.98 ab & 74.73 e & 28.47 f & 196.56 b & 3.01 c & 0.00 a \\
**MSW2** & 84.83 cd & 3.94 a & 2.65 a & 75.15 e & 28.05 f & 160.95 b & 2.73 c & 0.00 a \\
**MSW3** & 61.06 b & 7.22 d & 5.37 b & 71.73 c & 20.10 e & 49.65 a & 0.74 a & 0.00 a \\
**SS1** & 81.87 cd & 7.95 e & 3.02 a & 71.97 c & 9.29 b & 23.27 a & 0.62 a & 40.42 c \\
**SS2** & 66.37 b & 8.63 g & 2.56 a & 64.91 a & 9.50 ab & 57.83 a & 0.95 a & 18.70 b \\
**SS3** & 67.67 b & 8.40 fg & 3.06 a & 66.14 b & 6.44 a & 31.86 a & 0.61 a & 38.34 c \\ \hline \hline \end{tabular}  
* Data are mean values (n = 3), those with the same letter in the same column are not significantly different from each other (LSD, \(p<\) 0.05). Abbreviations: M: moisture; EC: electrical conductivity; OM: organic matter; C/N: carbon-nitrogen ratio; AT\({}_{\mathbf{4}}\): dynamic accumulated respiration activity; DIR: dynamic respymmetric index GI: germination index. All data are on a dry weight basis. ** Vegetal residue (VR); municipal solid waste (MSW); sewage sludge (SS).  
\end{table} 
Table 2: Properties of raw materials from industrial composting facilities \({}^{*}\). and polymeric fractions of the waste material. In the present study, both fractions were evaluated at the beginning and at the end of the process (Figure 1). This quantification allowed the observation of the degradation that these fractions suffered during composting (Figure 2). According to the results obtained in the polymeric fraction, the fibers content of the raw materials ranged between 30 and 40% of the dry weight (Figure 1a). As expected, and also reported earlier by others [34], the main fraction thereof, consisted of cellulose (10-20%). The fiber content was relatively constant among all the samples, regardless of the raw material. In contrast, the soluble fraction was highly dependent on it (Figure 1c). The SOC represented around 2.5% of the dry weight in MSW, but barely reached 0.2% in SS. On the other hand, in SS the majority of the soluble fraction was clearly the soluble protein. This result can be explained by the high content of nitrogen fraction contained in these residues due to their origin [35]. Nitric and ammonia fractions did not represent a considerable soluble fraction either in the SS or in MSW studied. Throughout the composting process, the bio-materials undergo a series of biotransformations. These changes are detectable by analyzing the variation in the soluble and polymeric fractions [25]. Therefore, in this study both fractions were also quantified in the compost produced (Figure 1b,d) despite the fact that in industrial scaling processes, waste can often not be biotransformed as correctly as in ideal composting. The variable content of these fractions in composts revealed situations in which biodegradation were more intense.