## 3 Results and Discussion  
### Reactor Performance  
Methane content in biogas was measured to determine the performance of reactor Figure 2a,b illustrates the methane production curve of both experiments for S/I ratio 1.5 and 2.5 comprising of all reactors (WSRS, BAWSRS, BARS, BAWS), the trend shows a continuous rise in methane production, reactor WSRS has shorter lag phase when compared with other reactors. For experiment 1(S/I ratio 1.5), methane production was started within a week, efficient methane production was noticed by the reactor WSRS i.e., 41\(\%\) on the fourth day of the experiment, whereas the startup phase for other reactors BAWSRS, BAWS was 29\(\%\) and 37\(\%\) on seventh and eleventh day respectively; for Experiment 2 (S/I ratio 2.5), WSRS, BAWSRS, and BAWS produced methane at 17\(\%\), 11\(\%\) and 3\(\%\) on the fourth, seventh and twentieth day respectively. Reactor RSBA showed the lowest methane production among all reactors in both experiments. Methane production for reactors other than WSRS was determined to slow because hydrolysis was the rate-limiting step in both experiments [33]. Hydrolysis of lignocellulosic material is mostly affected by its recalcitrant structure among lignocellulosic materials shorter hydrolysis, and enhanced methane production was observed for substrates having higher cellulose content, lignin concentration of each substrate effects total biogas production as well as the initial hydrolysis rate [34], the hydrolysis rate is shown in Table 4. Cellulose and hemicelluloses formulate almost \(\sim\)70% of the biomass and are linked to the lignin structural units all the way through covalent and hydrogenic bonds; thereby, the structure formulated is tremendously rigid and resistive against processing [35]. While comparing both ratios, a decrease in methane production and hydrolysis rate was observed for reactors of S/I ratio 20. Maximum K\({}_{\text{h}}\) was observed for reactor WSRS (Experiment 1, S/I ratio 1.5) followed by BAWSRS. This suggests that an increase in substrate concentration would lower the hydrolysis rate and methane production. After the startup phase, the maximum methane production recorded by reactors WSRS, BAWS, BARS, and BAWSRS (Experiment 1; S/I ratio 1.5) was 70.63%, 64.5%, 65%, 69%, respectively. Similarly, maximum methane production for reactors WSRS, BAWS, BAWSRS, and BARS (Experiment 2; S/I ratio 2.5) was recorded as 68.5%, 58%, 65.5%, and 18%, respectively. Furthermore, the graph of cumulative methane yield is shown in Figure 3a,b for both Experiments. The maximum methane yield observed for all reactors WSRS, BAWS, BARS, and BAWSRS of Experiment 1 were 393.08 NmLCH4/gVS, 177.96 NmLCH4/gVS, 188.299 NmLCH4/gVS, and 337.900 NmLCH4/gVS, respectively. Whereas, for Experiment 2, methane yield of reactors WSRS, BAWS, BARS, and BAWSRS were 244.78 NmLCH4/gVS, 65.79 NmLCH4/gVS, 15.74 NmLCH4/gVS, and 151.34 NmLCH4/gVS, respectively. Among both experiments, the combinations in Experiment 2 show an initial lag in methane production, the inhibition is likely due to higher lignin content and an increase in organic loading ratio (increase in the substrate concentration) [36]. Lignin has a recalcitrant structure that limits the degradation of lignocellulosic waste whereas cellulose and hemicellulose degrade after  
Figure 2: Methane % Potential of Reactors with (S/I ratio) (**a**) 1.5 and (**b**) 2.5.  
the hydrolysis process, the degradation of cellulose and hemicellulose in lignocellulosic material would govern methane production [37; 38]. Moreover, the substrates used in the present study show bagasse has higher lignin content and lower methane production. Lignin is the protective barrier that provides support to the lignocellulosic structure and resists any microbial attack and oxidative stress. Additionally, lignin is insoluble in water hence, anaerobic bacteria require more time to adhere on the substrate to start the anaerobic digestion.