Effect of Zero Valent Iron (ZVI) in Wastewater Treatment: A Review

Abstract

Cathodic hydrogen was produced in the presence of anaerobic zero valent iron (ZVI) corrosion by water. It can enhance microbial denitrification to convert nitrate to N2O and N2. Autotrophic denitrifying growth on ZVI can enhance nitrate removal. Results showed that by increasing nitrate removal rates, innocuous gases (N2O and N2) are produced rather than ammonium. Using steel wool with a small specific surface area instead of powdered ZVI, pH was not significantly increased. Little pH change was caused by corrosion. This is a positive condition for autotrophic denitrifying bacteria. ZVI was used in permeable reactive barriers (PRBs) process under anaerobic conditions. It used sulfate reducing bacteria for immobilization of heavy metals. In fermentation, methanogenesis and sulfate reduction was complete after adding ZVI to mixed anaerobic cultures. It was found that methane production increased and sulfate was reduced. This was due to readily utilizable ZVI which served as a slow-release electron donor for methanogenesis and sulfate reduction. ZVI has potential as a useful material in bioremediation.