Sulfate removal mechanism by internal circulation iron-carbon micro-electrolysis

Internal circulation iron-carbon micro-electrolysis (ICE) was used to treat sulfate in wastewater. The influences of the reaction time, aeration rate, pH, iron-carbon ratio, and the initial sulfate concentration on sulfate removal by ICE were investigated. The maximum sulfate removal efficiency was 76.6% under the following conditions: reaction time = 120 min, aeration rate = 0.5 m(3)/h, pH = 2, iron-carbon ratio = 1:1, and initial sulfate concentration = 500 mg/L. Scanning electron microscopy, energy-dispersive spectrometry, X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectroscopy analyses were performed to study the sulfate removal mechanism. The results showed that sulfate was mainly removed by two mechanisms: 1) sulfate may initially be reduced to SO32-, and then to S-2, which combines with H+ and Fe2+ to form H2S and FeS, which can be removed; 2) sulfate can be removed by flocculation and precipitation of Fe(OH)(2) and Fe(OH)(3). Therefore, the ICE process can be used as an effective method to remove sulfate from wastewater.

Automated summary

The study found that the internal circulation iron-carbon micro-electrolysis (ICE) is effective in removing sulfate from wastewater. Sulfate is mainly removed through reduction and flocculation and precipitation mechanisms.