Water contamination with numerous pharmaceuticals is an emerging concern since these pharmaceutical contaminants (PCs) are frequently found in environment and can cause certain adverse effects on ecosystems and health of human beings. Conventional wastewater treatment plants cannot effectively remove these PCs. Advanced treatment technologies have been developed to achieve an efficient removal of PCs, the high cost and limitations of these strategies have constituted a driving force for people to develop a cost-effective and environmentally-friendly approach. Microalgal remediation of contaminants has gained research interests as it is a solar energy driven, zero-waste production, and eco-friendly option to treat PCs contaminated wastewaters, followed by the subsequent utilization of produced biomass as a feasible feedstock for sustainable biofuel production. In this study, the ecotoxicological effects of two widely distributed PCs, sulfamethazine (SMZ) and sulfamethoxazole (SMX), and their mixture were comprehensively investigated using a green microalga, Scenedesmus obliquus, as a test organism. The calculated 96 h half-maximum effective concentration (EC50) of SMZ, SMX, and their mixture (1:1wt/wt) were 1.23, 0.12, and 0.15 mgL-1, respectively. The biochemical characteristics (total chlorophyll, carotenoid, carbohydrate, fatty acid methyl esters) of S. obliquus have been significantly affected. Elemental analysis of harvested biomass showed increase nitrogen and sulfur content with increasing of SMZ and SMX concentration. Despite their toxicity, S. obliquus exhibited 31.4-62.3% of the 0.025-0.25 mg SMZ L-1 and 27.7-46.8% of the 0.025-0.25 mg SMX L-1 in the mixture after 12 days of cultivation. The greater biodegradation observed at higher SMZ and SMX concentrations indicates that microalgal degradation of SMZ and SMX could act as an efficient adaptive mechanism to antibiotics. The metabolic pathways of SMZ and SMX were proposed according to mass spectroscopic analysis, formed because of hydroxylation, methylation, nitrosation, and deamination.

Biodegradation of sulfonamides using microalgae

2019 Spring National Meeting

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