## 3 Results and Discussion
### Aeration Tank Performance
FOG also results in an increased organic load that requires additional energy consumption due to increased aeration demand in the clarifier; hence, 35% of COD is in FOG form [13; 34]. In this study, the protein removal was quantified to assess the design efficiency of Bio-AS, Syn-AS, and CAS in removing proteins that cause biofoamation. Figure 4D shows that the raw PSW fed into the Bio-AS initially contained 96 mg/L of protein. During days 0 to 2, the Bio-AS aeration tank removed protein by between 50.2% and 51%. During day 3, protein depreciation was 51.5%, and the highest average protein removal obtained from days 4 to 10 was 99%. The PSW fed into the Syn-AS contained 29.4 mg/L of soluble proteins, and the protein removal observed was between 5% and 57% during the unsteady state, while the highest removal during the steady state was 92% on day 5. The CAS was fed with a concentration of 31 mg/L soluble protein, and the highest protein removal achieved during the steady state was 72%. These systems can reduce the soluble proteins; however, Bio-AS achieved the highest protein removal due to the presence of a biodefoamer that also enhanced sludge flocculation in the presence of oxygen. A high TSS concentration affects the treated wastewater's turbidity and harms water quality and aquatic life [35]. Figure 4H,I graphically illustrates the removal of TSS by Bio-AS, Syn-AS, and CAS at unsteady, transitional, and steady states. At an unsteady state (days 0-2), the Bio-AS removed 55.3% of TSS. During the transition state (day 3), 39% of the TSS was decreased; during the steady state (day 10), the highest TSS reduction was 88%. This indicated the effectiveness of biodefoamers against PSW constituents. The 48 h acclimation defoamer-producing cultures were added to enhance the attachment of the planktonic colloids into the sludge due to the charge neutralization of the surface charge of the solids and the biodefoamer. The synthetic defoamer (antifoam A concentrate) used in the Syn-As contained active silicon. Solubility and hydrophobicity of a defoamer are essential for the effectiveness of the defoamer; however, these conditions are not favorable for the AS microbial culture [36]. Throughout the unsteady state, TSS removal in Syn-AS ranged between 5.2% and 86%, whereas through the transition state, it increased to 34%; during the steady state, the highest TSS removal obtained was 59% in the aeration tank. A high concentration of COD in wastewater indicates high oxidizable organic and inorganic reducible substances, which leads to a decrease in DO, creating an anaerobic environment that deteriorates the efficiency of an aerobic treatment system. As depicted in Figure 4K,L, during the steady state (day 10), the Bio-AS achieved the highest COD removal of 60.2% on day 10. Syn-AS attained 24.4% removal during the unsteady state (day 1) but reached a maximum of 41.2% later during the steady state (day 6). Though the aeration tank can decrease the organic contaminants in the wastewater a secondary clarifier is necessary to further improve the quality of the wastewater by settling down the aggregates and clarifying the wastewater.