Removal of N,N-diethyl-m-toluamide (DEET) using Chlorella vulgaris: a study on its tolerance limits and its effects on biochemical composition

Abstract

N,N-Diethyl-m-toluamide (DEET) is one of the significant chemical formulations used extensively in personal care products as a preventive measure against mosquito-borne diseases. It has been detected in the aquatic matrix at various concentrations from ng/L to mg/L. Chlorella vulgaris is one of the potential algal species for the treatment of wastewater containing personal care products, and this study investigates the acute toxicity and removal potential of Chlorella vulgaris in the removal of DEET with its effects on pigments and biochemical composition. The 96-h EC₅₀ was calculated to be 17.4 mg/L, and the biochemical composition assessment revealed that lipid concentrations in Chlorella vulgaris increased until the tolerance limit. This investigation revealed that when DEET concentration crossed the tolerance limit (17.4 mg/L) in the medium, the pigments and biochemical concentrations reduced drastically, indicating Chlorella vulgaris inhibitory response beyond the tolerance limit, causing irreversible damage to the algal cells. Furthermore, Chlorella vulgaris removal potential at three different test runs, T1 (5 mg/L), T2 (10 mg/L), and T3 (25 mg/L) were studied. The most remarkable elimination in T1 test runs was 72% due to biodegradation, followed by T2 (35%) and T3 (15%). T1 conditions resulted in more significant lipid formation than other test runs, making biofuel for DEET-contaminated wastewater a feasible alternative.