Quantifying Glycogen in Solids at Full-Scale Enhanced Biological Phosphorous Removal Wastewater Facilities

Abstract

Glycogen is a chief metabolic storage pool in bacteria performing enhanced biological phosphorous removal (EBPR) and is a potential resource for the production of bio-based fuels and chemicals. Quantifying glycogen at full-scale EBPRs is necessary to evaluate viability. To more fully understand resource potential, both sampling location and lab-scale quantification methods were compared to ensure suitable assessment. Sampling location, before and after final clarification, indicated that clarification selects for high-glycogen flocs and concentrates glycogen with respect to solids—in this case by 51%. Two assays were compared for glycogen quantification of lyophilized sludge: acid treatment (.9 M HCl) and alkaline treatment [5 M potassium hydroxide (KOH)], both at 1°C for 3 h. Alkaline treatment recovered only 58% of glycogen in known standards versus 96% for acid treatment. The acid method was successfully applied to waste-activated sludge (WAS) from seven different treatment facilities, which ranged from 2.5 to 2.8% of solids as glycogen. The results represent the first broad survey of glycogen in full-scale EBPR systems and indicates that it is a modest resource potential.