Exploring the relationship between carbon redirection, microbial ecology and operational strategies in High-Rate Contact Stabilization (HiCS) Process

This study investigated the influence of solid retention time (SRT) and aeration on the efficiency of the high-rate contact stabilization (HiCS) process. Decreasing SRT from 3 to 1.3 days favored carbon capture, peaking its efficiency at 47%, but negatively impacted total Chemical Oxygen Demand (COD) removal. Lowering SRTs peaked protein and polysaccharide concentrations in EPS production at 176.2 mg protein/g VSS and 44.5 mg polysaccharide/g VSS respectively. Polyhydroxybutyrate (PHB) dominance in polyhydroxyalkanoates (PHAs) production was observed due to high wastewater acetate concentrations. Furthermore, extended aeration significantly affected treatment efficiencies and microbial community composition. Aquabacterium, being the most abundant species at 20.12%, could have a putative influence on the reactor's performance. These findings offer valuable insights into optimizing HiCS processes for wastewater treatment and advancing sustainable, energy-positive facilities.