Evaluation of Biofilm Development on Various Natural and Synthetic Media

Abstract

Thin film biological treatment systems are attracting increased interest as the need for more cost-effective methods for destruction or detoxification of hazardous organic wastes becomes more evident. The nature and extent of microbial coverage on the solid supports involved in such systems have thus far been matters of speculation. This study discusses an evaluation of the relative tendencies of microorganisms to colonize the surfaces of different types of natural and synthetic media under a variety of conditions. The media investigated were exposed to organic wastes in controlled laboratory experiments and examined using scanning electron microscopy for extent of biogrowth. The observations suggest that both the adsorption properties and surface texture of a solid affect biofilm development. Activated carbon, which is highly adsorbent and offers a relatively rough surface, supported significantly more biomass than did a synthetic carbonaceous adsorbent, an anion-exchange resin, a natural sand, or glass beads. Surface coverage was non-uniform and incomplete for all media, with a maximum observed coverage of approximately 50% for the activated carbon.