Influence of synthetic and natural polymers on the anaerobic granulation process

The influence of synthetic Percol 763 and natural chitosan polymers on the granulation rate of suspended anaerobic sludge was studied in laboratory-sc ale upflow anaerobic sludge bed (UASB)-like reactors. The results showed th at supplementation of the reactors with polymers, either natural or synthet ic, enhanced the granulation in comparison to control reactors (without the addition of polymers). A greater granulation was, however, obtained with c hitosan compared to that with Percol 763. Chitosan yielded a granulation ra te as high as 56 m/d compared to 35 m/d with Percol 763. The superior granu lation performance of chitosan was probably related to its polysaccharidic structure, hence acting similarly to the extracellular polymeric substances (EPS) in aggregating anaerobic sludge. The granules specific activities we re enhanced in the reactors supplemented with both polymers compared to tho se in control reactors. Overall, the results showed that polymers play a mo re critical role than microbial trophic groups in enhancing anaerobic granu lation in UASB-like reactors. (C) 1998 IAWQ Published by Elsevier Science L td. All rights reserved.