Removal of Mercury, Arsenic, and Cadmium in Synthetic Wastewater by Cyanobacterium Aphanothece halophytica

Abstract

Aphanothece halophytica is a halotolerant cyanobacterium that can grow undersodium chloride concentration range of 0.2 ??? 3.0 M and can tolerate to mercury, arsenic, andcadmium concentration at 4, 40, and 10 mg/L, respectively. The aim of this study was toinvestigate the reduction of mercury (Hg2+), arsenic (As3+), and cadmium (Cd2+) in syntheticwastewater by halotolerant cyanobacterium A. halophytica. These organisms were able toremove Hg2+, As3+, and Cd2+ in the synthetic wastewater about 70%, 55%, and 50%,respectively at pH 7.5 and ambient temperature. The optimal pH to reduce all heavy metals is6.0 at ambient temperature. By increasing the content of cyanobacterial cell used in theexperiment, the results showed that heavy metal removal depended on cell concentration.Temperature has no significant effect to remove all heavy metals. This work demonstratedthat the efficiency of Hg2+, As3+, and Cd2+ removal by A. halophytica in these conditionsdepended on pH and cell concentration, respectively.

Keywords: Cyanobacteria, synthetic wastewater, heavy metal removal.