Treatment of low-concentration uranium-containing wastewater utilizing Scenedesmus sp. with an emphasis on response surface methodology

Abstract

Microalgae possess various mechanisms to mitigate the toxicity of heavy metals. This study focused on the uranium removal potential of Scenedesmus sp. strain MTR 1901 from waters containing low concentrations of uranium contamination. Response surface methodology (RSM) utilizing central composite design through Design Expert software was employed to identify the key parameters and optimize factors such as pH, time, temperature, metal concentration, and biomass concentration in the process. The results revealed that uranium concentration, pH and time are statistically effective in uranium removal process. The removal efficiency improved from 14.36 % to 79.62 % when the pH was enhanced from 4 to 7.97 during the initial times. Additionally, as the uranium concentration increased from 1 mg to 5 mg/l, the removal efficiency declined from 100 % to 32.19 % in alkaline pH conditions. Increasing time from one to 96 h, the removal efficiency was decreased from 76.14 % to 61.24 %. The 1 g of the alga under the optimal condition (C₀ = 1.57 mg/l, pH 3.22, M = 1.31 g/l, T = 12.8 ^°C, Time = 53 h) can remove 1190 μg of uranium with an absorption efficiency of 99.54 %. The findings indicate that strain MTR 1901 is a promising candidate for the phytoremediation of uranium in aquatic environments that are contaminated with low levels of uranium.