## 4 Discussion  
The first two weeks were the acclimization process of bacteria, and then the formation of granules began. This explained the low treatment efficiency of both COD and TN removal in the initial \begin{table}
\begin{tabular}{c c c} \hline
**Enzymes** & **Percent Read** & **Pathway** \\ \hline Starch phosphorylase & 0.043 & EC:2.4.1.1 \\ \(\alpha\)-amylase & 0.043 & EC:3.2.1.1 \\ Glucoamylase & 0.001 & EC:3.2.1.3 \\ Pullulanase & 0.017 & EC:3.2.1.41 \\ \(\alpha\)-galactosidase & 0.036 & EC:3.2.1.22 \\ \(\beta\)-galactosidase & 0.072 & EC:3.2.1.23 \\ \(\alpha\)-glucosidase & 0.060 & EC:3.2.1.20 \\ \(\beta\)-glucosidase & 0.113 & EC:3.2.1.21 \\
1,4-\(\alpha\)-glucan branching enzyme & 0.043 & EC:2.4.1.18 \\ Oligo-1,6-glucosidase & 0.002 & EC:3.2.1.10 \\ \hline \end{tabular}
\end{table} 
Table 4: Starch hydrolytic enzymes detected in the granular sludge sample. Figure 8: Pathway from starch to pyruvate in the SBR system. Starch was metabolized to pyruvate through glycolysis. All enzymes were present in the SBR system. process. These parameters significantly increased in the following weeks after the lag phase, despite the fact that the load of COD input also increased. According to the investigation of [PERSON] et al. [26], which used a SBR system to treat municipal wastewater, the efficiency of COD removal was also remarkably high after the acclimatization process of bacteria in the system, which grew to 94.5% after 20 days. Similar results were also reported in previous studies [27; 28; 29]. The value of the organic load rate (OLD) in this study was significantly higher, reaching 7.4 kg COD/m\({}^{3}\)-day when the system was in a stable state, which was two times higher than the similar operating SBR system for municipal wastewater treatment reported by [PERSON] et al. [30]. This could explain why the wastewater from the noodle-manufacturing village contained more easily degradable organic matter such as starch, in comparison to municipal wastewater. However, the loading rate for N was higher in the case of municipal wastewater, as compared to the noodle-manufacturing wastewater at 0.36 g N/L-day and 0.26 g N/L-day, respectively. In an aerobic granular wastewater treatment system, the removal efficiency of TN is normally higher than that of TP through the nitrification process carried out by living microorganisms, which could eventually produce N\({}_{2}\) gas from the treatment system. Most of the phosphorous is taken up and transformed into microorganism biomass and/or precipitated by complex components within active sludge, and remains in the treatment system [31; 32]. The gasification of TN (mostly in the form of ammonia) to N\({}_{2}\) gas is conducted by microorganism due to anoxic condition created by granular activated sludge, which a conventional aerobic wastewater treatment is usually limited [33]. The dominance of TN over TP removal efficiency was also observed in this study, but the difference was not significant (83% vs. 75%). The TN and TP removal rate reached a high value indicating that the settleability of the sludge in the SBR system was relatively fast and effective, and led to a reduction in the suspended microorganism biomass, which mainly contributed to a high nitrogen and phosphorous concentration in effluent [34; 35]. This was reflected by \(\text{SVI}_{30}\) values, a parameter describing the ability of the sludge to settle and compact, that gained the optimal range from 100 mL/g to 200 mL/g after two weeks and was sustained around 90 mL/g for the rest of the operational periods. At this range, the sludge was characterized by a quick settling and high compact, and more importantly, pulling down more particulate matters while settling to produce a clear and good quality of treated water. The \(\text{SVI}_{30}\) value usually performs a higher value (more than 250 mL/g) when a system is undergoing startup and the sludge is just formed, meaning that the sludge has a poor and slow settleability. This happened in the first two-week operation of the SBR system in this study.