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Low cost solutions convert plastics from food waste and renewable raw materials

Low cost solutions convert plastics from food waste and renewable raw materials

15-Sep-12

Until recently corn, sugarcane and other edible crops are being used to make bioplastics. That sets the bioplastics industry up for competition against the world�s food supply, which is already under enormous stress from population growth and climate change among other factors. Several initiatives have been taken by leading giants from end use industry like Cokei, Ford and many more. Soft drink giant Coca-Cola is making a multi-million dollar investment in bio-based companies in an effort to accelerate the development of a PlantBottle made entirely from plants.Ford is increasingly working on newer applications of bio based plastics in its cars. Now Starbucks has made its foray into the field of environmentally friendly polymers with a reduced carbon footprint. 1.3 bln tons of food is trashed, dumped in landfills and otherwise wasted around the world every year. Research is being conducted to explore the low cost possibility of converting food waste and scrap into polymers. Starbucks is exploring the possibility of recycling its used coffee grounds and other food waste to make bioplastics and other useful products. The new food waste initiative was kickstarted by Starbucks Hong Kong, after The Climate Group approached research team leader Carol S.K. Lin at the City University of Hong Kong for help. Using food waste offers a workaround, but the challenge has been to develop a cost-effective conversion process. Lin and her team found a solution by ramping up the process with the help of enzymes from fungi. The extra enzymes help to convert the carbohydrates in food waste into simple sugars. The food biorefinery process works by blending the baked goods with a mixture of fungi that excrete enzymes to break down carbohydrates in the food into simple sugars. The blend then goes into a fermenter, a vat where bacteria convert the sugars into succinic acid. The technology has other environmental benefits. Fewer pollutants enter the atmosphere, because the waste is not incinerated, and the CO2 produced is reused during the biorefining process.

Bioplastics that are naturally synthesized by microbes could be made commercially viable by using waste cooking oil as a starting material. This would reduce environmental contamination and also give high-quality plastics suitable for medical implants, according to scientists presenting their work at the Society for General Microbiology's Autumn Conference at the University of Warwick. The Polyhydroxyalkanoate (PHA) family of polyesters is synthesized by a wide variety of bacteria as an energy source when their carbon supply is plentiful. Poly 3-hydroxybutyrate (PHB) is the most commonly produced polymer in the PHA family. Currently, growing bacteria in large fermenters to produce high quantities of this bioplastic is expensive because glucose is used as a starting material. Work by a research team at the University of Wolverhampton suggests that using waste cooking oil as a starting material reduces production costs of the plastic. "Our bioplastic-producing bacterium, Ralstonia eutropha H16, grew much better in oil over 48 hours and consequently produced three times more PHB than when it was grown in glucose," explained Victor Irorere who carried out the research. "Electrospinning experiments, performed in collaboration with researchers from the University of Birmingham, showed that nanofibres of the plastic produced from oils were also less crystalline, which means the plastic is more suited to medical applications." Using waste cooking oil is a double benefit for the environment as it enables the production of bioplastics but also reduces environmental contamination caused by disposal of waste oil. The next challenge for the group is to do appropriate scale-up experiments, to enable the manufacture of bioplastics on an industrial level.

A robust microorganism that enables efficient production of biobased malic acid has been developed. Novozymes has succeeded in developing a fungus that enables production of malic acid from renewable raw materials instead of oil. Malic acid is used as a flavor enhancer in the food industry and can be converted into other chemical derivatives used for a variety of plastic, polymer and resin products. Malic acid also has significant potential as a building block in the chemical industry. Along with succinic acid and fumaric acid it belongs to the group of C4 dicarboxylic acids. C4 acids can be converted into 1.4-butanediol (BDO), that can be further converted into numerous chemicals, including plastics, polymers and resins for use in everything from golf balls and skateboard wheels to printing inks and cleaning agents. The annual global market for malic acid is around 60,000 tons and has a value of US$130 mln with a growth rate of 4% per year. The market for BDO and derivatives is around 1.4 mln tons at a value of US$2.8 bln and with an annual growth rate of 3%.

 
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