Year: 2013
Type: dissertation
Abstract: Municipal solid waste (MSW) management is a costly necessity. Petroleum-based plastics are \ncommonplace in MSW of modern, throw-away societies. Petroleum-based plastics do not \nbreakdown from natural processes in landfills and take up large amounts of valuable space. \nCompostable plastics offer a sustainable solution to petroleum-based plastics. Polylactic acid \n(PLA) is a plastic made from 100% renewable resources, is compostable at industrial composting \nconditions (high heat, high moisture) and is also recyclable. Published research describing \nresponsible waste management of PLA is scarce. The University of Wisconsin-Stevens Point \n(UWSP) currently implements PLA plastic ware at dining facilities on campus. This research \ncompared two end-of-life options of post-consumer PLA waste. First, efficiency of industrial \ncompostability of PLA waste was investigated. The composting experiments were performed \nusing controlled conditions at 55°C comparing the degradation effects on 5, 10, 20 and 30 % (by \nweight) additions of PLA cups vs. paper cups to equal amounts of compost feedstock. PLA \ntreatments degraded significantly more than paper treatments at all treatment levels. A \nsubsequent plant germination trial evaluated the effects of this compost on plant growth. No \nsignificant difference was found among treatments, suggesting that degraded PLA is not toxic to \nplant growth. As an alternative to composting, chemical recycling of PLA was investigated. \nChemical recycling of PLA has potential to be a closed-loop process, increasing the \nsustainability of PLA product use. Collection for chemical recycling has been implemented at \nUWSP, titled the FRESH project, and is being managed by the WI Institute for Sustainable \nTechnology. No standards currently exist for the cleaning/processing of PLA waste in \npreparation for chemical recycling. Chemical recycling of post-consumer PLA waste was \nperformed via hydrolysis with a focus on two industrial rinse-processing methods (high- and \nlow-level) and compared to pre-consumer PLA. Results indicated no significant differences \nbetween the high- and low-level treatments on the quality of the lactic acid/oligomer product.
Author: Waneta T. Kratz
Language: English
Subfield: Biomaterials
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W3161563871