Evaluation of Fe²⁺/Peracetic Acid to Degrade Three Typical Refractory Pollutants of Textile Wastewater

In this work, the degradation performance of Fe²⁺/PAA/H₂O₂ on three typical pollutants (reactive black 5, ANL, and PVA) in textile wastewater was investigated in comparison with Fe²⁺/H₂O₂. Therein, Fe²⁺/PAA/H₂O₂ had a high removal on RB5 (99%) mainly owing to the contribution of peroxyl radicals and/or Fe(IV). Fe²⁺/H₂O₂ showed a relatively high removal on PVA (28%) mainly resulting from ·OH. Fe²⁺/PAA/H₂O₂ and Fe²⁺/H₂O₂ showed comparative removals on ANL. Additionally, Fe²⁺/PAA/H₂O₂ was more sensitive to pH than Fe²⁺/H₂O₂. The coexisting anions (20–2000 mg/L) showed inhibition on their removals and followed an order of HCO₃⁻ > SO₄²⁻ > Cl⁻. Humic acid (5 and 10 mg C/L) posed notable inhibition on their removals following an order of reactive black 5 (RB5) > ANL > PVA. In practical wastewater effluent, PVA removal was dramatically inhibited by 88%. Bioluminescent bacteria test results suggested that the toxicity of Fe²⁺/PAA/H₂O₂ treated systems was lower than that of Fe²⁺/H₂O₂. RB5 degradation had three possible pathways with the proposed mechanisms of hydroxylation, dehydrogenation, and demethylation. The results may favor the performance evaluation of Fe²⁺/PAA/H₂O₂ in the advanced treatment of textile wastewater.