Studies on bioremediation of Zn and acid waters using Botrycoccus braunii

ARECO, M.; HAUG, E.; CURUTCHET, G.

Journal of Environmental Chemical Engineering

ELSEVIER

Año: 2018 vol. 6 p. 3846 - 3856

2213-3437

Abstract: In the present article the effects of Zn(II) on Botryococcusbraunii in terms of growth and the photosynthesis-respiration metabolismas well as the ability of this microalgae to remove zinc present inwastewaters is described. The photosynthetic and respiration rates (CO2and O2) are affected by increasing metal concentration in solution, andtherefore B. braunii growth rate decreases to a half,neverthelessthemaximum value of biomass reached (770 ± 40 mg l-1) is the same and thebiomass remains viable throughout the range of concentrations studied (0-80 mgl-1). B. brauniiexposedthe ability to reverse the acidic conditionsof the medium, showing a pH increase from 5.2 ± 0.2 till values above 8.0± 0.4, favoring the precipitation of different zinc hydroxicomplexes.Zn(II) specific removal increases along with initial metal concentrationand with pH. The amount of metal removed from solution increasesignificantly when metabolic processes are involved, with respect toadsorption (non-metabolic process). The stoichiometric relationshipbetween H+ release and zinc uptake in slightly acidic conditions is 1:1,and the adsorption kinetics follows a pseudo-second order model. Thecontinuous removal of the metal was achieved along 200 days, reaching amaximum value of zinc removal of 3.4 gr gr-1. The remediation of heavymetals such as zinc, nickel and copper, as well as nitrates present in aleachate obtained from bioleaching of sediments of a contaminated stream(Reconquista River) was successfully performed. B. braunii surface wascharacterized using scanning electron microscopy (SEM) and energydisperse X-ray spectroscopy (EDS).