BIODEGRADABILITY IN SOIL AND COMPOSTING O F MICROBIAL POLYESTER

A petri dish burial test was carried out with poly(3-hydroxybutyrate-c o-3-hydroxyvalerate) [P(3HB-co-3HV)] films at 25 degrees C in 11 kinds of soils and one mature moist compost preparation. The rate of biodeg radation of the films was strongly dependent on the, soil textures. Th e fastest rate of soil was 100% weight loss of the Nm at 50 days, whil e the slowest rate of soil was 20% at 3 months. Relationships between this test, the field testing at the collecting places of 9 kinds of so ils and other factors were investigated. The degrading films seemed ab le sometimes to remain iri soils for one year or more depending on the properties of soils and the environment. Next, the garbage with 3% ad dition of P(3HB-co-3HV) bags was applied to the composting verificatio n test plant. It was found that P(3HBto-3HV) bags were-able to compost with garbage. It was confirmed that shredded P(3HB-co-3HV) bags did n ot prevent garbage from aerobic fermenting and composting; thus the ma terial was degraded and became invisible to the naked eye in approxima tely 10-20 days.