A simple method suitable to test the ultimate biodegradability of environmentally degradable polymers

A straightforward experimental set-up derived from the Biometer Flask previously utilized for experiments of pesticides biodegradation, has been adopted for testing the ultimate biodegradability of natural, synthetic and semi-synthetic polymeric materials on solid substrates such as soil and mature compost. The use of these whole substrates as incubation media in respirometric experiments, may negatively affect the accuracy of the test due to the large amount of carbon dioxide developed from the blanks, especially in the presence of specimen degrading at low or moderate rates. In the present test procedure soil and compost samples are diluted with perlite, a naturally occurring inert aluminum silicate widely utilized in horticultural applications, in order to ensure optimal conditions for the microbial growth while reducing the carbon dioxide emissions from the blanks. The results so far reported clearly indicate that the adopted procedure is extremely valuable and versatile for the appreciation of even subtle differences in the biodegradation rate of different polymeric materials, as well as for long-term degradation experiments.