Production and degradation of polyhydroxyalkanoates in waste environment

Polyhydroxyalkanoates (PHAs) are energy/carbon storage materials accumulate d under unfavorable growth condition in the presence of excess carbon sourc e. PHAs are attracting much attention as substitute for non-degradable petr ochemically derived plastics because of their similar material properties t o conventional plastics and complete biodegradability under natural environ ment upon disposal. In this paper, PHA production and degradation in waste environment as well as its role in biological phosphorus removal are review ed. In biological phosphorus removal process, bacteria accumulating polypho sphate (poly P) uptake carbon substrates and accumulate these as PHA by uti lizing energy from breaking down poly P under anaerobic condition. In the f ollowing aerobic condition, accumulated PHA is utilized for energy generati on and for the regeneration of poly P. PHA production from waste has been i nvestigated in order to utilize abundant organic compounds in waste water. Since PHA content and PHA productivity that can be obtained are rather low, PHA production from waste product should be considered as a coupled proces s for reducing the amount of organic waste. PHAs can be rapidly degraded to completion in municipal anaerobic sludge by various microorganisms. (C) 19 99 Elsevier Science Ltd. All rights reserved.