Plant polymer biodegradation in relation to global carbon management

Natural polymers such as starch, protein, and algae are renewable and sustainable materials. They are used in many industrial applications such as polymeric blends for films, fibers, and injection molded articles. However, biodegradability of these materials in anaerobic sludge digestion is largely unreported.Extensive laboratory results were acquired to elucidate biodegradability and biodegradation kinetics of the selected materials according to ASTM D5210. There was no remarkable difference in biodegradability of wheat, native corn, and modified corn starches. For the protein samples, wheat gluten biodegraded to a great extent than soy protein isolate. For the algal samples, Spirulina biodegraded to a great extent than Nannochloropsis. A first order kinetic equation was used to fit all experimental data.A separate set of 14C data examined if the carbon source, which is a building-block for all plant polymers, was bio-based (recent carbon) or fossil-based. The former is a part of global carbon cycle, and the latter is believed to cause adverse greenhouse gas effects resulting in global warming.