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Biodegradation of weathered polypropylene microplastic (pellets) in marine microcosm environment

Karakoulak Spyridon

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Year 2021
Type of Item Diploma Work
Bibliographic Citation Spyridon Karakoulak, "Biodegradation of weathered polypropylene microplastic (pellets) in marine microcosm environment", Diploma Work, School of Chemical and Environmental Engineering, Technical University of Crete, Chania, Greece, 2021
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The usage of plastic products has overtaken the last years a big portion of goods we use in our daily life, as a result waste is produced from their usage, in many cases those wastes end up in aqueous recipient and mostly the ocean. This results in the aesthetic and functional downgrading of the recipient ecosystem thus endangering it. One of the most common types of plastic that someone can encounter in the coastlines and the ocean is microbeads (pellets), due to their important role in the industry of plastics. During their exposure to the environment pellets undergo alteration of their physicochemical and mechanical characteristics, also known as weathering/aging, which makes the vulnerable against microorganism attack.The purpose of this research is the study of the effects of microbial communities from the coastal area of gulf of Souda either combined with the fungi Acremonium tubakii on pellets of polypropylene, in simulated marine environment in a batch reactor, where glucose and weathered microbeads are the carbon sources.The microbeads were previously exposed for 4 months to UV radiation, then they were placed in sterilized flasks. Sterile seawater was added to the flasks as well as Copper (Cu) and Glucose, and the microbial community. Then we placed the flasks on stirring devices at 100rpm for 2 months. We had sampling at intervals of 15 days for the estimation of the weight loss of the pellets, measuring the activity of laccase enzyme, monitoring the surface of the microbeads, the total proteins within the biofilm, the total dissolved carbon as well as the biofilm attached to the microbeads. From the above results we came into a conclusion that there was a significance change in the reduction of weight of the pellets, that the microorganisms in the bioreactors of 100ml that was monitored are responsible and that the source of carbon they had access to was the microplastic pellet and 0,1gr of Glucose that was injected in the first and the 30th day.

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