RELEVANCE OF AQUATIC BIODEGRADATION TESTS FOR PREDICTING DEGRADATION OF POLYMERIC MATERIALS DURING BIOLOGICAL SOLID-WASTE TREATMENT

The aquatic biodegradability of cellulose and cellulose acetate with d egrees of substitution (d.s.) in the range of 1.5 to 3.0, was compared with the mineralization under laboratory controlled composting condit ions. In line with previous observations, it was found that cellulose acetates with d.s. less than or equal to 2.5 were readily mineralized to CO2 in the controlled composting test. The degradation rate was cle arly affected by the degree of substitution (d.s. 1.5 > d.s. 2.5 > d.s . 3.0). Surprisingly, however, biodegradation of cellulose acetate mat erials was not observed in the aquatic Sturm test. Modifications of th e pH and the inoculum source in an attempt to improve the activity of fungi and actinomycetes in the aquatic environment, did not increase C O2-evolution, It is concluded that the relevance of modified Sturm tes ts is limited for predicting complete biodegradation of polymeric mate rials during biological waste processing. For evaluation of the compos tability of polymeric products or packaging materials, more relevant l aboratory controlled composting rests should be used. (C) 1997 Elsevie r Science Ltd.