Increase of bacterial population by cross-linked polyvinylpyridine added to a model system for continuous aerobic treatment

Abstract

Cross-linked polyvinylpyridine was previously reported to improve the process of aerobic treatment by enhancing the rate of removal of chemical oxygen demand. In this work, a simplified model system for continuous aerobic treatment was used, consisting of synthetic wastewater, cross-linked polyvinylpyridine in bead form, and a single bacterial species. Addition of the resin to the model treatment system enhanced the rate of removal of total organic carbon as well as the increase of the bacterial population. However, no significant change was observed in the amount of total organic carbon removed per concentration of suspended free bacterial cells, or in the respiration activity of these cells. Therefore, the improvement of the aerobic treatment process by the addition of cross-linked polyvinylpyridine could be explained in terms of an increase of the bacterial population caused by the presence of the resin. Since the resin is an excellent polymeric adsorbent for removal of carboxylic acids and other acidic organic materials from aqueous solution, it is presumed that addition of the resin to the aerobic treatment system removes acidic waste products of bacteria from the cell surface by adsorption on the resin surface, and results in increase of the bacterial population.