COD removal and nitrification of low-strength domestic wastewater in aerobic granular sludge sequencing batch reactors

Acetate-fed granules were used to start-up reactors for the treatment of low-strength domestic wastewater at 25 °C (R1) and 35 °C (R2). Two hundred milligrams per liter COD in domestic wastewater was easily removed. Granular seeds acclimated to NH4+-N removal after domestic wastewater was used and the specific NH4+-N removal rate increased linely after 7-day operation. Effluent NH4+-N was below 5 mg l−1 and NH4+-N removal efficiency increased to above 90% after 22-day operation with cycle time of 2 h in both reactors with 0.3 kg m−3 day−1 NH4+-N loading rate. In addition, granular seeds cultivated at 25 °C showed good adaptation to higher temperature and the granules in R2 at 35 °C showed good stability in 4-month operation.