Aerobic Granulation in a Sequencing Batch Reactor Using Real Domestic Wastewater

Aerobic granulation has been extensively investigated in recent decades but most researchers have focused their studies on granule formation in laboratory-scale reactors using synthetic wastewaters at high organic loading rates (OLR) (OLR>2.5kgCOD.m-3.d-1). This research studied the aerobic granulation in a sequencing batch reactor (SBR) using real domestic wastewater with an OLR at or lower than 2kgCOD.m-3.d-1. The reactor was operated in three different stages (Stage I, II, and III), according to the applied OLR (1.4, 1.0, and 2.0kgCOD.m-3.d-1, respectively). After 140days of operation (Stage II), the reactor biomass consisted mainly of compact mature granules (average diameter of 0.7mm) with a good settling ability (SVI30 approximately 53mL.g-1). The OLR increase caused a partial disintegration of the mature granules during the beginning of Stage III. However, the granules were able to quickly recover after the disturbance caused by the higher OLR. The reactor was effective at removing carbon and nitrogen compounds, especially when operated with an OLR of 2kgCOD.m-3.d-1, providing an average removal efficiency of 92% for CODD and 96% for NH4+-N. The results demonstrated that aerobic granules can be formed, using real domestic wastewater, with an effective carbon and nitrogen removal. (C) 2013 American Society of Civil Engineers.