Full scale performance of the aerobic granular sludge process for sewage treatment

• A robust and stable granule bed of more than 8 g L−1 was formed and maintained with an SVI5 of 45 mL g−1.
• The energy usage was 13.9 kWh (PE150, removed year)−1.
• The volume needed for the AGS plant was 33% lower than the existing CAS plant.
• Maximum volumetric conversion rates for N and P were 0.17 and 0.24 kg (m3 d)−1 respectively.

Recently, aerobic granular sludge technology has been scaled-up and implemented for industrial and municipal wastewater treatment under the trade name Nereda®. With full-scale references for industrial treatment application since 2006 and domestic sewage since 2009 only limited operating data have been presented in scientific literature so far. In this study performance, granulation and design considerations of an aerobic granular sludge plant on domestic wastewater at the WWTP Garmerwolde, the Netherlands were analysed. After a start-up period of approximately 5 months, a robust and stable granule bed (>8 g L−1) was formed and could be maintained thereafter, with a sludge volume index after 5 min settling of 45 mL g−1. The granular sludge consisted for more than 80% of granules larger than 0.2 mm and more than 60% larger than 1 mm. Effluent requirements (7 mg N L−1 and 1 mg P L−1) were easily met during summer and winter. Maximum volumetric conversion rates for nitrogen and phosphorus were respectively 0.17 and 0.24 kg (m3 d)−1. The energy usage was 13.9 kWh (PE150·year)−1 which is 58–63 % lower than the average conventional activated sludge treatment plant in the Netherlands. Finally, this study demonstrated that aerobic granular sludge technology can effectively be implemented for the treatment of domestic wastewater.