Post-treatment of swine wastewater using aerobic granular sludge: Granulation, microbiota development, and performance

Abstract

We studied the applicability of aerobic granular sludge (AGS) technology in association with upflow anaerobic sludge blanket (UASB) reactors for swine wastewater (SWW) treatment. Granule formation, long-term operational evaluation, and the system performance for simultaneous C, N, and P removals were assessed. Finally, the AGS microbial changes were evaluated by metagenomic analysis. Aerobic granulation occurred after 54 days of operation, and 81% of the granules had a diameter above 1.0 mm after 96 days of the experiment. The granules formed were spherical, had cohesive structure and good sedimentation capacity, although they were classified as non-resistant. After the sludge granulation (steady-state), high COD, BOD and ammonia removals were found, although the removals of TN and TP were considered moderate. Nonetheless, overall, a good operational stability was achieved. The metagenomic analysis revealed that the microbial groups suffered great influence from the substrate characteristics, but they are commonly found in AGS systems.