## 3 Results
### Thermogravimetric Analysis
The decrease in moisture content can be associated with the hydroxyl group's breakdown during the torrefraction process. Generally, biomass material such as sugarcane bagasse absorbed the moisture, usually bond to this hydroxyl group, thus subjecting the biomass to thermal treatment, lowers the moisture content [4,35]. It is of great importance to highlight that the obtained MC for all the samples is within the acceptable limit for downdraft gasification. The decrease in moisture MC and VM with torrefraction relatively increased the FC of the samples. At torrefraction temperature of 300 \({}^{\circ}\)C, the FC of M\({}_{\text{e}200}\) increased from 16.76% to 23.18%, while at 350 \({}^{\circ}\)C, it increased further to 51.37%. M\({}_{\text{a}200}\) increased from 26.54% to 31.77% for the torrefraction temperature of 300 \({}^{\circ}\)C. However, M\({}_{\text{a}250}\) showed the lowest FC content of 1.15% due to its high volatile matter content as compared to other torrefraction temperature. Recalling that FC content is determined by difference using volatile matter as one of the parameter hence an increase in volatile matter will corresponding decrease FC. Indeed, the increase in FC content with temperature increase is in agreement with the findings in literature [6,36,37]. Moreover, a combination of increased temperature and residence time are required to obtain a biomass with high FC content. This is advantageous during gasification or combustion as high content of FC translates to better heat of combustion [20]. It is a necessary constituent of solid fuel needed to achieve a stable combustion process. After the complete combustion of the samples, the leftover inorganic solid residue known as ash is typically composed of calcium, silica, iron and phosphorus. The presence of these components in the ash could lead to agglomeration, corrosion and fouling in \begin{table}
\begin{tabular}{c c c c c c} \hline
**Sample** & **MC (wt \%)** & **VM (wt \%)** & **FC (wt \%)** & **AC (wt \%)** & **FR** \\ \hline M\({}_{\text{a}200}\) & 5.05 & 44.90 & 26.54 & 23.51 & 0.59 \\ M\({}_{\text{a}250}\) & 4.16 & 76.89 & 1.15 & 17.80 & 0.014 \\ M\({}_{\text{a}300}\) & 3.56 & 40.94 & 31.77 & 23.73 & 0.77 \\ M\({}_{\text{a}350}\) & 5.00 & 31.11 & 26.50 & 37.39 & 0.85 \\ M\({}_{\text{e}200}\) & 4.05 & 49.6 & 16.76 & 29.59 & 0.33 \\ M\({}_{\text{e}250}\) & 3.63 & 70.62 & 13.87 & 11.88 & 0.19 \\ M\({}_{\text{e}300}\) & 3.65 & 36.89 & 23.18 & 36.28 & 0.62 \\ M\({}_{\text{e}350}\) & 2.95 & 29.88 & 51.37 & 15.8 & 1.71 \\ \hline \end{tabular}
\end{table} 
Table 1: Proximate analysis of the blended ratio of torrefied sewage sludge (SS) and raw bagasse (BG). gasifiers [27]. Hence, low AC, as obtained in M\({}_{\rm e250}\), is recommended to curb the mechanical problem associated with high ash content. Finally, the fuel ratio used in determining the combustibility of a solid fuel showed an increasing trend at higher temperatures. The FR of 1.7 obtained for the M\({}_{\rm e350}\) sample compares very close with the FR range of 1.4-1.5 reported for optimum combustion performance of coal [38]. Although the increase in fuel ratio usually creates an ignition difficulty, it still results in an improved and stable combustion performance. Another solid fuel property of importance, higher heating value (HHV) shown in Table 2, was calculated following the correlation of [PERSON] et al. [39] and the second correlation adapted from [PERSON] [40] study. The established correlation used in calculating the HHV of the samples considered the vital solid fuel properties, namely: volatile matter, fixed carbon and ash content. From Table 2, the HHV obtained for all samples varied between 12.25-23.62 MJ/kg. This is consistent with [PERSON] et al. [37] study where an HHV range of 13.55-16.64 MJ/kg was reported for sewage sludge torrefaction at a temperature range of 200-350 \({}^{\circ}\)C. [PERSON] et al.