Enhanced coagulation and oxidation by the Mn(VII)-Fe(III)/peroxymonosulfate process: Performance and mechanisms

Area of Science:

• Environmental Chemistry
• Water Treatment Technologies
• Advanced Oxidation Processes

Background:

• Conventional coagulation struggles with micropollutant removal and disinfection by-product formation.
• Optimizing coagulation requires innovative pre-oxidation and activation strategies.

Purpose of the Study:

• To evaluate a combined permanganate pre-oxidation and Fe(III)/peroxymonosulfate (PMS) coagulation process (Mn(VII)-Fe(III)/PMS).
• To investigate the removal efficiency of dissolved organic carbon (DOC), turbidity, and micropollutants.
• To elucidate the underlying reaction mechanisms and synergistic effects.

Main Methods:

• Pre-oxidation with permanganate (Mn(VII)) followed by Fe(III)/PMS coagulation.
• Analysis of iohexol and sulfamethoxazole removal.
• Investigation of redox cycling involving natural organic matter (NOM), iron, and manganese.

Main Results:

• The Mn(VII)-Fe(III)/PMS process significantly improved removal of DOC, turbidity, and micropollutants compared to Fe(III) coagulation alone.
• Enhanced removal of specific micropollutants like iohexol and sulfamethoxazole was observed.
• A 21.9% reduction in the formation potential of volatile disinfection by-products (DBPs) was achieved.

Conclusions:

• The Mn(VII)-Fe(III)/PMS process offers a promising approach for advanced drinking water treatment.
• Synergistic interactions between NOM, Fe, and Mn facilitate PMS activation and micropollutant degradation.
• This process provides effective coagulation and micropollutant control, with implications for improving conventional water treatment.