Biodegradation of plastic bottles made from ‘Biopol’ in an aquatic ecosystem under in situ conditions

Abstract

Experiments have been carried out in Lake Lugano, Switzerland, in order to study the biodegradation of poly(3-hydroxyalkanoates) (PHA) in an aquatic ecosystem under natural conditions. Commercially available plastic articles made from PHA, such as bottles and films, were incubated for 254 days in a water depth of 85 m. Shampoo bottles were positioned precisely on the sediment surface by the use of a small manned submarine. A set of bottles was attached to a buoy in order to incubate plastic material in diffent water depths. When incubated in the water column or on the sediment surface, a life span of five to ten years for this specific bottle type was calculated. In situ degradation rates of 10 to 20 mg/d were determined. PHA films were completely degraded when incubated in the top 20 cm of the sediment. The results clearly demonstrate that in an aquatic ecosystem (water column as well as sediment) under in situ conditions (i.e. low temperatures, seasonal variations of the oxygen concentration) plastic goods made from PHA are degraded.