Performance assessment of aerobic granulation for the post treatment of anaerobic effluents

Present study investigates the formation of aerobic granular biomass and its comparative performance in treatment of anaerobic effluents using two lab scale sequencing batch reactors (SBR), (Reactor 1 and 2) fed with medium strength synthetic wastewater and anaerobic effluent respectively. The granulation was better in reactor 1 with biomass concentration of 7014 mg/L while in reactor 2 it could reach only 3910 mg/L. Reactor 1 showed good organic and nitrogen removal performance. The COD removal efficiency in reactor 1 was more than 90% (average similar to 94 +/- 2%) reaching to a maximum of 98% with influent concentration of 1400 +/- 12 mg/L. While in reactor 2, it was only 55 +/- 9% reaching to a maximum of 64% with influent concentration of 213 +/- 47 mg/L. Total nitrogen removal efficiency with influent of 140 +/- 3 mg/L in reactor 1 was more than 90% compared to average removal efficiency of 78 +/- 7% with influent of 84 +/- 25 mg/L in reactor 2. Reactor 1 showed better nitrate removal of 91 +/- 9%(influent nitrate concentration of 53 +/- 6 mg/L) while as reactor 2 showed better ammonia removal of 87 +/- 25% with influent concentration of 67 +/- 29 mg/L. Sludge characterization by Scanning Electron Microscopy and Fourier Transforms Infrared Spectroscopy revealed bacterial morphologies of rod, coccus and filament coexisted in the granules. The preliminary findings in this study may supplement insights about application of aerobic granulation in post treatment of anaerobic effluents. (C) 2019 Published by Elsevier B.V.