Accelerated Reduction and Recycling of Solid Wastes by Application of Enzymes Capable of Green Plastic Degradation

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Attempts were made to accelerate the degradation of an polyvinyl alcohol (PVA)-starch blend plastic, Mater-bi AF10H, by applying starch- and PVA-degrading bacteria and enzymes.Mater-bi degradation tests by an activated sludge, simulating its degradation in natural environment, resulted in the ultimate weight loss of less than 40 % and no film breakage.Applications of a starch-degrading bacterium and a-amylase caused more rapid and extensive weight loss (max. 50 %) than the activated sludge, however the apparent film breakage was not also observed.On the other hand, when a PVA-degrading bacterium or enzyme was applied, a maximal weight loss of ca. 70 % was achieved and film breakage occurred.The enzyme application was especially effective, and led to the film fragmentation into small pieces within 10 days under an optimal condition.These suggested that the degradation of PVA fraction is important and requisite for complete degradation of Mater-bi.On the other hand, an acetate cellulose plastic could not be degraded by applying lipase and/ or cellulase enzymes.However, when it was tre-treated by UV irradiation, about 60 % of weight loss was performed at an optimal condition.As a conclusion, this is a great success for accelerating degradation of green plastics, leading also to acceleration of reduction and recycling of solid wastes.