EFFECTS OF INTENSIVE MICROBIAL METABOLISM ON STARCH-FILLED POLYETHYLENE FILMS IN CONTROLLED COMPOSTING WINDROWS

抄録

Low density (LDPE) and high density (HDPE) polyethylene films filled with starch up to a maximum level of 20% by weight were tested for biodegradation under different environmental conditions. Composting windrows consisting of various putrescible waste and assembled for controlled biostabilization management under static conditions were used. The physical and chemical deterioration of the polyethylene-starch films exposed to a controlled composting environment were recorded and analyzed with respect to the different composting evolution and were compared with the data collected in pure culture systems and in bench scale tests simulating an aerobic biostabilization process. Evidences are presented on the partial removal of starch from the different films as a consequence of massive surface colonization by various microorganisms. Loss of starch is accompanied by a small but significant drop in the average molecular weight and decrement in mechanical strength. In the case of a composting trial experiencing prolonged severe temperature conditions, a small but spectroscopically detectable oxidation of the polyethylene matrix was also observed. Efficiency of the controlled composting systems can be claimed in assessing reproducible conditions in an accelerated biostabilization of putrescible matter and hence versatility in the evaluation of the degradation of plastic manufacts.