Joseph Greene, Ph.D.
Department of Mechanical Engineering Mechatronic Engineering and Manufacturing
Technology
California State University, Chico
Chico, California, USA 95929-0789
Abstract:
Biodegradable and oxodegradable plastics were evaluated in a commercial composting operation and in a marine environment. The plastic materials degraded in an in-vessel compost operation along with food waste from San Francisco, California. Biodegradable plastics included, corn starch based biobag, Mirel PHA bag, BioTuf Ecoflex bag, Husky corn starch based trash bag, PLA lids, sugar cane lids, and Kraft paper. Also buried were polyethylene shrink-wrap, UV degradable plastic bag, and oxodegradable plastic bag.
The samples were placed in perforated plastic sacks and mixed with food waste at NorCal and Jepson Prairie Organics (JPO) composting operation in Vacaville, California. After 180 days, the materials that completely degraded included PLA lids, Mirel bags, Ecoflex bags, Husky bags, and corn starch trash bags. Small fragments of sugar cane lids and Kraft paper were visible. The oxo-biodegradable plastic bags, LDPE plastic bags and UV-degradable plastic bag did not experience any degradation and did not fragment into smaller pieces.
Anaerobic marine biodegradation of several biodegradable plastics
were evaluated in laboratory marine environment. The samples were placed
in 100-ml jars with ocean water and held at 30oC for 90 days in a combined
aerobic and anaerobic environment. The mass of each sample was measured
at 30 day increments. After 90 days, Mirel PHA experienced 70% disintegration.
None of the other samples experienced any disintegration. Mirel PHA biodegrades
in marine water while exposed to anaerobic environments. BioTuf bag,
Husky corn starch based trash bag, PLA straw, sugar cane lid, and Kraft
paper do not biodegrade in anaerobic environments. Oxodegradable
plastic bags do not biodegrade in marine water environment and behave very
similar to polyethylene plastic bags in these environments.
Biography:
Dr. Joe Greene is a professor in the Mechanical Engineering Mechatronic Engineering and Manufacturing Technology Department. He received a Ph.D. in Chemical Engineering in 1993 from the University of Michigan. Joe began teaching in August of 1998 after a 14-year career with General Motors Corporation in Detroit, Michigan. His research interests include compostable and biodegradable polymers, recycled plastics, composting technology, anaerobic digestion, and biodiesel technology.
Dr. Greene has spent the last three years researching the use of biodegradable plastics in California for the California Integrated Waste Management Board. He has published his biodegradable plastics research work at five international conferences since 2005. Currently, Dr. Greene is researching ways to convert the organic sugars in beer and rice waste to biodegradable plastics, e.g., Polylactic acid. Also, Dr. Greene is actively pursuing research with biodiesel to help our university farm and local farms become more sustainable by producing biodiesel to run tractors and heat farm buildings.