The effect of growth inhibiting compounds of grease trap waste on Candida tropicalis ATCC 20962

Abstract

The production of chemicals through a circular economy is becoming increasingly important and one way to achieve this is through the utilisation of waste streams. One such waste stream that holds potential for production of chemicals through biochemical methods is grease trap waste (GTW). However, before this waste stream can be used in bioprocesses, it is crucial to understand its effects on the process. This study explores the toxicity of the GTW on the growth of Candida tropicalis ATCC 20962, a yeast that is applied to convert lipids into valuable long-chain dicarboxylic acids (LCDAs). The GTW is characterised and the inhibition of the different components on the growth of C. tropicalis is examined. Results indicate significant inhibition of yeast growth at a concentration of 40 g/L of GTW and higher. Further analysis confirms that the presence of anionic detergents may partially contribute to this inhibition. In contrast, the pesticides, free fatty acids and heavy metals did not appear to significantly affect the growth of C. tropicalis. Although this study suggests that GTW could be a suitable feedstock for Candida tropicalis ATCC 20962, more research is required to identify other potentially toxic components and to determine if pre-treatment is necessary for industrial applications.