Study on Removal of NH₄⁺-N by Zero-Valent Iron (ZVI or Fe⁰) in Advanced Coking Wastewater Treatment

Abstract

In this study, the feasibility of a new chemical agent named zero-valent iron (ZVI or Fe0) was used to investigate for removal of NH4+-N from coking wastewater. Reaction pH, dose of Fe0, initial NH4+-N concentration and temperature were considered variable parameters. The pH was observed as the major critical parameter. The removal rate of NH4+-N decreased as the pH increased from 3 to 6 and then increased from pH 6 to pH 9. At pH of 8.0 about in coking wastewater, the NH4+-N removal might be depended on the types and quantity of corrosion products on the surface of Fe0. The removal rate of NH4+-N increased with increase of temperature in the studied range of 10–60°C. At an initial NH4+-N concentration of 134.17 mg/L, Fe0 concentration of 6 g/L, temperature of 60°C and initial pH of 8.0, the removal rate of NH4+-N increased to 54.94%. The dose of Fe0 is determined according to the nitrogen content in coking wastewater.