Effects of temperature and inoculum on the degradability of poly-ε-caprolactone during composting

The effects of temperature and type of inoculum on the biodegradability of poly-epsilon-caprolactone (PCL) were tested in a bench-scale composting reactor under controlled laboratory composting conditions. The difference between the quantity of CO2 evolved in the presence of the PCL versus the quantity evolved in the absence of the PCL was regarded as the quantity of CO2 evolved in association with the decomposition of PCL. The degradability of PCL was calculated as a ratio of the quantity of PCL decomposition to the mixed quantity of PCL in the compost raw material. The effect of temperature on the degradability of PCL was examined. Temperatures of 40, 50, and 60 degrees C were used, and the optimum temperature for the PCL degradation was found to be approximately 50 degrees C, at which ca. 62% of the PCL was decomposed over 8 days. The effect of the type of inoculum on the degradability of PCL when composting at 50 degrees C was then examined. The degradability of PCL was significantly different for each of the two types of inocula used, with the degradability observed when using one inoculum being half that observed when using the other. (C) 1998 Elsevier Science Limited. All rights reserved.