## 3 Results
### Material Flow Analysis
The lines are proportional to the mass of each flux. Figure 2: Sankey diagram of mass balance for OFMSW + green waste treatment in kg (wet waste) (the lines are proportional to the mass of each flux). In Table 4, the degradation factors are referred to the biodegradable materials. Paper-like materials present the higher degradation factor with printed paper (61%), cardboard (51%), and dirty paper (43.3%). These materials present high VS, and they consist primarily of cellulose and lignin, organic polymers difficult to decompose. However, the high decompositions are justified by the screening, mixing and the elevated temperatures found during the thermophilic phase of composting process that contribute to the rapid degradation of lignocellulosiculose [52]. Similar high degradation rates have been observed elsewhere [43] concerning various paper-like materials present in OFMSW composting. It is also stated that if the paper-like materials do not exceed 27% of OFMSW, degradations of 36-65% are feasible in controlled conditions with a retention time of 45 days. Concerning biowaste, the degradation factor has an average 48%, while the green waste 15%. The above results suggest that the retention time in the ACT is not sufficient for the complete decomposition of the biodegradable materials of biowaste. Green waste serves as a bulking agent and is shredded to medium-sized particles presenting a low degradation factor [53]. Physical characteristics such as bulk density, particle size, and porosity are important factors for fragment decomposition level. The structure of green waste (containing lignocellulosic materials) appears difficult decomposition and requires specific lignocellulosic microorganisms (and enzymes) to improve it degradation and retention time more than 12 weeks [54; 55]. In order to produce mature compost, [12] stated that degradations of 40-83% of the carbon contained in the biowaste are required, while [56] reported 62-66% and 66-77% degradation of carbon for garden waste and food waste, respectively. \begin{table}
\begin{tabular}{l l} \hline \hline
**Fraction** & **Degradation Factor (\%)** \\ \hline Biowaste & 48 \\ Paper & 61 \\ Dirty paper & 43.3 \\ Cardboard & 51 \\ Green waste & 15 \\ Soft plastic (PE) & 10 \\ Other inert & 5 \\ Other materials & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Degradation factors (%\(w/w\)) for the volatile solids of waste fractions in the aerobic composting tank process. Figure 4: Sankey diagram for nitrogen mass balance in kg for OFMSW + green waste composting processing (the lines are proportional to the mass of each flux). Plastic materials present close to zero degradation for this process; only LDPE abandoned in the form of shopping bags can be accounted to have a 10% degradation. Although LDPE films have presented some degradation only in the harsh environment of the composting process [55], and the degraded portion is meager. The mechanical processes employ throughout the composting process, such as turning mixing and screening, can result in polymers being sheared into smaller fragments during the conventional composting process and could explain the above degradation factor, as it is often apparent in household and commercial organic waste [57; 58]. An additional issue that must be considered is the rapid increase in biodegradable plastic materials that have started to replace the traditional PE film. Their biodegradability is dependent on the composting conditions and the chemical composition of each material [59]. The second sub-process (refinery unit-RFU) is a mechanical separation stage based on sizing the material using a 'flip-flop' sieve with 10 by 10 mm mesh holes, followed by a gravimetric air separator in line with a gravimetric air cyclone to collect the lightweight material. Table 5 presents the transfer coefficients for each material. Bulky and heavy materials are mainly rejected into residue.