Reduction of nickel content from the model solution by consortium of fungal pellets and green algae

Abstract

The accumulation of Ni from the model aqueous solution (100 mg/L) by pellets of Aspergillus niger (A. niger) together with the green algae Chlorella sp., as a microbial consortium, during five days was compared. In the experiment, already formed pellets were used (5 mL A. niger conidia in Sabouraud Dextrose Broth, shaked with 200 rpm for 5 days). The experiment was carried out under static and also dynamic conditions at 25 °C. Oxidation-Reduction-Potential (ORP) and pH were measured as well in the first, third and fifth days. Microbial consortium (A. niger with Chlorella sp.) was found always more effective – reduction of the Ni content was higher 48.95 mg/L (under static conditions) and 56.45 mg/L (dynamic conditions), pH values were medium acidic (5.84 static conditions), to weak acid (6.52 dynamic conditions). Monitored ORP values were significantly reduced in the range of -309 mV up to - 385 mV in the Ni model aqueous solution, when the both microorganisms were present. This reduction was attributed to the anoxic conditions occurred when the Reactive Oxygen Species (ROS) radicals were produced by the photoactive pigments in the algae chloroplasts.