Qualitative Changes in Upflow Anaerobic Sludge Blanket Granules during Extracellular Polymer Extraction by Autoclaving.

Abstract

Extracellular or surface polymers play a major role as a matrix keeping the cells together and mediating the adhesion of bacteria in natural or man-made eco-systems. It is presumptive that the bacterial aggregation in upflow anaerobic sludge blanket reactors is brought about in the form of granules by the combination of extracellular polymeric material and inorganic ash. The extracellular polymeric material in the granules of upflow anaerobic sludge blanket reactor was extracted by the autoclaving technique and qualitative changes in the granules before and after autoclaving were investigated with the help of scanning electron microscopy. Autoclaving for thirty, sixty and ninety minutes intervals was carried out and the effect of autoclaving time on the extraction of extracellular polymeric material was also studied. Most of the extracellular polymeric material could be extracted at 30 min autoclaving time without significant damage to the bacterial cells. 90 min of autoclaving resulted in the release of slightly more extracellular material but caused damage to the cells. 30 min autoclaving time seems to be suitable for the extraction of extracellular polymeric material from the upflow anaerobic sludge blanket granular sludges.