## 3 Results and Discussion
### Bioethanol Production Process  
Tall fescue biomass obtained from saline sites (average sample) before and after alkaline treatment was analyzed for chemical composition (cellulose, hemicellulose, lignin) [13]. The biomass was ground by a knife mill with 2 mm sieve and treated with alkali, i.e., 1.5% NaOH. The chemical structure analysis of tall fescue biomass showed that the alkaline treatment effect caused an increase in the content of cellulose from 33.69% to 50.41% (approx. 17%), a potential substrate in the process of obtaining biofuels. Moreover, partial degradation of hemicellulose from 34.74% to 25.23% (over 9%) was found. However, in the case of lignin content, which is a strong obstacle in the biomass conversion process, a decrease from 17.08% to 12.35% (almost 5%) was observed after alkaline treatment. Overall, the biomass of tall fescue from saline areas exhibits delignification after alkaline treatment and additionally solubilization of part of hemicellulose [13; 44]. The effect of alkaline treatment on tall fescue biomass from saline soils was confirmed using Scanning Electron Microscopy (Hitachi, Tokyo, Japan) shown in Figure 4.  
Significant changes on the surface of tall fescue biomass were observed before and after pretreatment. Figure 4a shows that untreated biomass has intact and rigid structure, which effectively blocks access to lignocellulosic. On the other hand, after pretreatment with sodium hydroxide (Figure 4b), SEM image of biomass shows structural damage and partial purification of the biomass surface. It can be concluded that NaOH degrades the bonds in lignocellulosic, which increases its surface area and makes it more accessible to enzymes [45; 46; 47]. Figure 3: Correlation between the salt content in the soil and above-ground plant parts of tall fescue. Then, the SSF process was performed, which ensures optimal synergy of enzymes and distiller's microorganisms. The enzymes Flashzyme Plus 200 (AB Enzymes GmbH, Darmstadt, Germany) and Celluclast 1.5 L (7:3 \(v\)/\(v\)) in the amount of 10 FPU-g\({}^{-1}\) in total and the yeast _Saccharomyces cerevisiae_ in the amount of 0.5 g\(\cdot\)L\({}^{-1}\) were used. Fermentation tests were performed on tall fescue biomass samples obtained from saline soils with different levels of salinity, and the amount of ethanol was determined using High Performance Liquid Chromatography (Figure 5). In the SSF process, ethanol was obtained in the range of 8.62-10.60 g\(\cdot\)L\({}^{-1}\) for all tall fescue biomass samples obtained from saline soils in the range of 0.70-6.85 g NaCl\(\cdot\)L\({}^{-1}\), and for which the Na\({}^{+}\) content in dry matter was from 2.45 to 8.66 mg\(\cdot\)g\({}^{-1}\). It was found that both the level of soil salinity and sodium content in tall fescue biomass had no significant effect on the amount of ethanol obtained. For example, for sample FA_1 (soil salinity: 6.85 g NaCl\(\cdot\)L\({}^{-1}\) and Na\({}^{+}\) content in biomass: 2.72 mg\(\cdot\)g\({}^{-1}\)) and sample FA_7 (soil salinity: 1.49 g NaCl\(\cdot\)L\({}^{-1}\) and Na\({}^{+}\) content in biomass: 8.57 mg\(\cdot\)g\({}^{-1}\)), despite the extreme values of soil salinity and sodium content in the biomass, the concentration of ethanol was obtained  
Figure 4: SEM images of tall fescue biomass (**a**) before and (**b**) after NaOH pretreatment. Figure 5: Ethanol concentration of tall fescue biomass after the SSF process (Statistica 13.0). at a similar level of approx. 9.7 g\(\cdot\)L\({}^{-1}\). In conclusion, in general, tall fescue biomass from saline soils has great potential of producing bioethanol with an average concentration of 9.66 g\(\cdot\)L\({}^{-1}\) (19.32 g\(\cdot\)100 g\({}^{-1}\) biomass), which makes obtaining approx. 245 L of ethanol per ton of raw material (DM) possible and from one hectare of degraded soil approx. 1.7 m\({}^{3}\) of ethanol. It is worth mentioning that in literature reports, tall fescue is also mentioned as a crop that is a potential raw material for the production of second-generation bioethanol [48].