Separation of PHA-accumulating cells in activated sludge based on differences in buoyant density

Abstract

Polyhydroxyalkanoates (PHAs) are polyesters found in prokaryotic cells as carbon and energy storage materials. The formation of PHB, the homopolymer of 3-hydroxybutyrate (3HB), was reported by Lemoigne (1926). In 1974, Wallen and Rohwedder (1974) reported the occurrence of a copolymer of 3-hydroxyvalerate (3HV) and 3-hydroxybutyrate in an extract from activated sludge. This was the fi rst report on the occurrence of PHAs that includes monomeric units other than 3-hydroxybutyrate.