Nutrient uptake of two microalgae from culture medium under nickel treatment

Phycoremediation is essential for purifying wastewater of heavy metals to ensure a sustainable environment, as these components can be detrimental to organisms upon entering the food chain. Among heavy metals, nickel is vital at low concentrations due to its presence in the active sites of many metalloenzymes in algae. However, at high concentrations, it disrupts the functioning of many metabolic reactions. This study examines the effects of nickel treatment on the uptake of macro- and micronutrients in medium by algae via ion exchange pathways or in competition with other metals. The study aims to determine the effects of nickel exposure on macro- and micronutrient uptake in algae and evaluate the bioremediation potential of Desmodesmus pannonicus and Scenedesmus aldavei under varying NiSO₄ concentrations. Additionally, it assesses growth responses, elemental composition changes, and alterations in functional groups to determine the tolerance and effectiveness of these algae in Ni(II) removal from contaminated environments.

The bioremediation abilities of Desmodesmus pannonicus and Scenedesmus aldavei were evaluated spectrophotometrically by measuring growth rate, chlorophyll-a, and chlorophyll-b for 14 days. Bioremediation properties were also analyzed using inductively coupled plasma optical emission spectroscopy.

Growth parameters varied with concentrations (p ≤ 0.05). Both species were found to have bioremediation capabilities up to the concentration of 1 M NiSO₄, which increased the absorption of Na⁺ ion content (p ≤ 0.05). However, the Mg(II), Ca(II), and K contents in the dry mass changed with the concentration (p ≤ 0.05). FTIR analysis was used to identify changes in specific functional groups in the samples, including carboxyl, amine, hydroxyl, and carbonyl.

Desmodesmus pannonicus and Scenedesmus aldavei exhibit significant potential for Ni(II) bioremediation, showing tolerance to NiSO₄ concentrations of up to 1 M. Compared to other organisms in the literature, Scenedesmus aldavei is an excellent model for phycoremediation studies.