[Electron microscopy of extracellular polymeric substances in activated sludge]

Many problems arise with the TEM preparation of activated sludge flocs because the specimen material contains up to 98% of water. It is difficult to preserve the ultrastructure beyond dehydration and to make the polymers visible, which cannot be visualized with standard methods. The method presented here renders satisfying results. The important role of the exocellular polymers for the structure, size and density of flocs can be well illustrated. Furthermore many structure patterns could be found differing largely from each other but occurring regularly as structure elements.