Effect of Polymer on Aerobic Granulation in SBAR for Wastewater Treatment

Aerobic granulation is an environmental biotechnology developed for the purpose of high-efficiency wastewater treatment. The distinguishing characteristics of aerobic granules attribute superiority to this technology in comparison with the conventional activated sludge processes. Increase in process stability, higher density, stronger microbial structure, higher biomass retention, good settling ability and ability to withstand high organic loading are such advantages of aerobic granules over conventional activated sludge. In this research, COD removal efficiency with glucose carbon source was evaluated by aerobic granules in SBAR (Sequencing Batch Airlift Reactor) with a 4 hours cycle time. To investigate the role of polymer adding in aerobic granulation, two reactors simultaneously were used. R1 and R2 were determined respectively as control and polymer adding reactors with working volume of 4.5 L. Experiments were done at different organic loading rates (OLRs) ranging from 0.72-5/4 kg COD/(m3.d). The results represent the high capability of aerobic granules in COD removal and yellow and large-sized black filamentous granules with diameters of 0.5-7 mm were formed in the reactors. With high settling capability of granules, sludge volume index (SVI) decreased to less than 100 mL/g. Finally it was indicated that adding of chitosan polymer had positive impact on granulation so that R2 produced 17% and 27% yellow and large-sized black filamentous granules more than R1, respectively.