## 3 Results  
### Changes in Influent and Effluent Wastewater Characteristics  
Activated sludge pH assessment was performed with dissolved oxygen (DO) concentration = 8.2 \(\pm\) 0.5 mg/L during the aeration phase. Sludge inoculum mixed liquor suspended solids (MLSS) was 10.2 \(\pm\) 2.0 g/L. MLSS of the SBR working sludge was 2.75 \(\pm\) 0.25 g/L at the start of the experiments. Overall chemical properties of the influent wastewater are summarized in Table 1.  
The results showed that the pH level in alkaline reactor was 7.5 right after the acclimization cycle and then slightly increased to 8.0 at 24 h but did not reach the influent value 8.50 (Figure S1). However, in acidic reactor, pH decreased from 7.4 (at acclimatization cycle) to 6.6 at 24 h. The pH in alkaline reactor was closer to the 'acclimatization cycle' pH = 7.5 due to the nitrification process' tolerance to slightly higher pH than acidic pH, while acidic influence is inappropriate for the nitrification process (ammonium conversion to nitrites). The differences in IC concentration (Table 1) in the influent of both reactors (IC = 70.2 \(\pm\) 8.0 mg/L in acidic reactor and IC = 123.9 \(\pm\) 22.0 mg/L in alkaline reactor) were influenced by pH regulation. IC concentration in the effluent from acidic reactor had a significant decrease compared with control (without inhibitor); IC concentration remained under 3 mg/L from 24 h to 72 h (Figure 1c). The high DO concentration ensured nitrification under aerobic conditions. The pH drop in the acidic reactor affected its alkalinity, which was observed as a decrease in IC concentration. The same trend has been shown earlier [2]. IC concentration in the effluent from alkaline reactor increased after inhibitor addition and reached 36.5 mg/L at 72 h (Figure 1c). Limitation of inorganic carbon source combined with AOB inhibition by alkaline pH can lead to high FA formation and AOB dynamics modifications [21]. Thus, the high IC concentration in alkaline reactor effluent acted as a buffer for the AOB, and the further inhibition process was not intensified. However, in acidic reactor, effluent IC concentration rapidly decreased after the pH regulation and low pH showed a potentially stronger influence on both AOB and NOB, which can also be influenced by the low inorganic carbon source to buffer nitrification process acidity. Electrical conductivity (EC) increased in both reactor effluents from 0 h to 24 h due to influent EC increase after inhibitor addition. After 24 h, EC stayed almost constant; thus, treated wastewater had higher salinity after inhibitor influence. NaOH and HCl addition contributed to non-biodegradable wastewater fraction increase. Thus, the ASP process had less treatment efficiency because of biological treatment interruption. COD concentration increased in the acidic reactor effluent between 0 h and 48 h of operation, which is related to sludge washout from the reactor. At 48 h, COD concentration was the highest--170.0 mg/L (COD removal only 30%). However, in the alkaline reactor, effluent COD was under 68.0 mg/L from 0 h to 72 h (Figure S2). The initial COD removal efficiency was 72%; therefore, COD removal was not affected in alkaline reactor (75%). Total phosphorus (TP) and PO4-P did not change significantly in both reactor effluents from 0 h to 72 h after inhibitor addition (Tables S1 and S2).