Case study of aerobic granular sludge and activated sludge—Energy usage, footprint, and nutrient removal

Abstract

This study demonstrates a comparison of energy usage, land footprint and volumetric requirements of municipal wastewater treatment with aerobic granular sludge (AGS) and conventional activated sludge (CAS) at a full‐scale wastewater treatment plant characterized by large fluctuations in nutrient loadings and temperature. The concentration of organic matter in the influent to the AGS was increased by means of hydrolysis and bypassing the pre‐settler. Both treatment lines produced effluent concentrations below 5 mg BOD7 L‐1, 10 mg TN L‐1, and 1 mg TP L‐1, by enhanced biological nitrogen‐ and phosphorus removal. In this case study, the averages of volumetric energy usage over one year were 0.22 ± 0.08 and 0.26 ± 0.07 kWh m‐3 for the AGS and CAS, respectively. A larger difference was observed for the energy usage per reduced P.E., which was on average 0.19 ± 0.08 kWh P.E.‐1 for the AGS and 0.30 ± 0.08 kWh P.E.‐1 for the CAS. However, both processes had the potential for decreased energy usage. Over one year, both processes showed similar fluctuations in energy usage, related to variations in loading, temperature, and DO. The AGS had a lower specific area, 0.3 m2 m‐3 d‐1, compared to 0.6 m2 m‐3 d‐1 of the CAS, and also a lower specific volume, 1.3 m3 m‐3 d‐1 compared to 2.0 m3 m‐3 d‐1. This study confirms that AGS at full‐scale can be compact and still have comparable energy usage as CAS.

Community successional patterns and inter-kingdom interactions during granular biofilm development

“…Aerobic granular sludge is a biofilm-based process for wastewater treatment that has received much attention in recent years. This technology displays several advantages compared to the activated sludge process, achieving an advanced nutrient removal in plants requiring about 50% less space and 20% less energy demand (Bengtsson et al, 2019; Ekholm et al, 2023). Aerobic granules are generally developed from activated sludge in sequencing batch reactors (SBRs), where aggregates with high microbial density and diversity are obtained.…”