Approximately one-fifth of the world’s population does not have access to safe water, and two-fifths suffer the consequences of unacceptable sanitary conditions due to contamination of water resources with various synthetic and geogenic compounds, which are being leached from agricultural, industrial and domestic activities. Biotechnological approaches are the most suitable methods for tackling the aquatic pollution in an ecofriendly manner. A freshwater microalga, Chlorella vulgaris was utilized for the effective removal of a model emerging contaminant (EC), diazinon from aqueous phase. Diazinon is one of the most widely used organophosphorus insecticides for agricultural activities, and it is highly toxic to mammals and other non-target organisms. C. vulgaris showed a highest removal capacity (93.66%) of diazinon at 20 mg L−1 within 12 days. The growth of C. vulgaris was significantly affected at high concentrations of diazinon, showing more than 30% growth inhibition at 40 mg L−1 after 12 days of cultivation. Significant enhancement of the microalgal growth in the exponential growth phase suggested a less/non-toxic nature of the metabolites of diazinon. Biochemical properties, including carotenoid, chlorophyll and antioxidant enzymes of C. vulgaris were influenced by diazinon at relatively high concentrations. The degradation rate constant (k) and the half-life (T1/2) of diazinon (0.5-100 mg L−1) ranged between 0.2304-0.049 d−1 and 3.01-14.06 d, respectively. Microalgal metabolism of diazinon produced a less toxic by-product, 2-isopropyl-6-methyl-4-pyrimidinol (IMP), as identified by gas chromatography mass spectroscopy (GC-MS). This study demonstrated that C. vulgaris is highly tolerant of diazinon, could be voluntarily involved in the removal of traces of diazinon from contaminated wastewater and has potential application in the removal of such an artificial toxins using microalgae.

Utilization of microalgae for the removal of Emerging Contaminants (ECs) from aqueous phase: A bioremedial approach

253rd National Meeting (2017)

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