## 4 Discussion  
As many as 30 VOCs (out of 84 total) in all analyzed scenarios followed first-order kinetics for emissions in storage. Table 1 presents the summary of VOCs and their adherence to first-order kinetics. The apparent lack of adherence to the first-order kinetics model could be due to several reasons. First, some VOCs were measured at very low concentrations, and the apparent linear increase of cumulative emissions was observed (Supplementary Materials). The second reason pertains to VOCs that were initially emitted but, after the third or fourth day, a decrease in concentration was observed. SPME sampling could also be affected by competitive VOC adsorption and displacement from the SPME fiber coating [39; 40; 41; 42]. This means that SPME sampling of VOCs could be affected by apparent higher emission rates and greater affinity of a particular VOC to the SPME fiber coating. This phenomenon should be further investigated. It was also found that some individual VOCs reacted differently to CRDF structural modification (data presented in Appendix A, Table 1). The technology for real-time VOC detection and quantification in occupational settings is improving [43; 44; 45]. Sensors for the identification of explosion risks, including pellistors (thermal sensors) and nondispersive infrared (NDIR) sensors, are available and could be suitable for monitoring VOCs in storage. Metal oxide sensors (MOS), photoionization detectors (PIDs), and electrochemical sensors are suitable for VOC concentration range from \(\sim\)1 ppmv to a low %, \(\sim\)1 ppbv to below 1%, and low ppmv levels, respectively [43]. Conventional chromatographic analysis requires sophisticated equipment as well as surely being non-online. On the one hand, the constant reduction of gas chromatograph-mass spectrometer (GC-MS) prices and low-budget apparatus, available for less than \(\epsilon\)50,000, can be observed. Nowadays, there are also developed \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**VOC Kinetic Parameters**} & \multirow{2}{*}{**Unit**} & \multicolumn{3}{c}{**CRDF Type**} \\ \cline{3-5}  & & **Ground** & **Pelletized** & **Pelletized with** \\  & & **(Control)** & **(Treatment)** & **Binder** \\ \hline \(E_{0}\) – maximum emission potential & \(\upmu\)g\(\cdot\)kg\({}^{-1}\) & 20,238 \(\pm\) 5848 & 2760 \(\pm\) 331 & 7487 \(\pm\) 1459 \\  & **\%** & - & **86.4** & **63.0** \\ \hline \(k\) – emission constant rate & \(\upmu\)day\({}^{-1}\) & 0.280 \(\pm\) 0.152 & 0.307 \(\pm\) 0.073 & 0.251 \(\pm\) 0.088 \\  & **\%** & - & **-9.6** & **10.3** \\ \hline \(t_{0.5}\) – half time of emission & day & 2.5 & 2.3 & 2.8 \\  & **\%** & - & **8.8** & **-11.6** \\ \hline \(r\) – emission rate & \(\upmu\)g(kg\(\cdot\)day)\({}^{-1}\) & 5666.6 & 847.4 & 1879.3 \\  & **\%** & - & **85.0** & **66.8** \\ \hline \(R^{2}\) – determination coefficient & - & 0.876 & 0.976 & 0.947 \\ \hline VOC emission kinetic parameters from ground (loose) CRDF (control), pelletized CRDF and pelletized CRDF with a binder (WG) \(\pm\) standard error, with relative mitigation values, \% obtained after structural modification in comparison to control CRDF (bold font). Volatile organic compounds (VOCs), Carbonized refuse-derived fuel (CRDF). & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The volatile organic compounds emission kinetic parameters from ground (loose) CRDF (control), pelletized CRDF and pelletized CRDF with a binder (water glass, WG) \(\pm\) standard error, with relative mitigation values, % obtained after structural modification in comparison to control CRDF (bold font). modifications of chromatographical equipment (fast gas chromatography - FAST-GC or Fast Gas Chromatography-Mass Spectrometry--FAST-GC/MS) that allow complete analysis within a few minutes (e.g., a whole measurement time of around 7 min) [46]. Likewise, solid phase microextraction fast gas chromatography-mass spectrometry (SPME-FAST-GC/MS) systems were applied for trace aroma compound analysis [47].