Study of the Aerobic Biodegradability of Plastic Materials under Controlled Compost

Abstract

Management of municipal solid waste is a serious problem in the current world. Synthetic plastics have been used for various purposes, and annual production of the plastics in 2001 reached about 15 million tons in Japan, and 177 million tons in the world. However, synthetic plastics with high performance and stability cause serious problems in waste management. To solve the problem of plastic waste, biodegradable plastics have attracted the special attention of the public as the plastics of the 21st century, since they are biologically degradable and environmentally friendly. However, before the use of biodegradable plastics spreads, it is crucial to establish the test methods for their biodegradation in the environment. The Biodegradable Plastics Society1,2 has conducted two field experiments for estimating the degradation of biodegradable plastics in soil at more than 20 locations (including one location in the U.S.) over a period of 3 years. The results showed that all of the tested plastics were degraded in soil. Hoshino3 et al. reported on the influence of weather conditions, and soil properties for the degradation of biodegradable polymers. Nishide4 et al. reported that the degradation of biodegradable polymers occurred under aerobic conditions as compared to anaerobic conditions. Many studies on the degradation behaviour in aquatic and terrestrial environments were reported and several standard test methods were established in 2000 in the world, such as JIS K69505 (ISO 14851) and JIS K69516 (ISO 14852), relevant to aquatic environments and JIS K69537 (ISO 14855) for controlled composting condition, respectively. Especially JIS K6953 based on ISO 14855 is an excellent test-method, which automatically calibrates the evolved carbon dioxide by gas chromatography although it is yet presenting some difficulties. First, the reactor is suitable for large-scale tests and the apparatus is expensive. Second, it costs a great deal to examine specimens to develop biodegradable polymers, compounds and manufactured goods. The focus of this study is to develop the evaluating and screening test method for the biodegradation of plastic materials with a simplified apparatus on a laboratory scale.