Chemical pretreatment of formaldehyde wastewater by selected Advanced Oxidation Processes (AOPs)

Chemical oxidation processes: Fenton process and catalytic ozonation with Mn2+ ions were investigated for effectiveness of formaldehyde (FA) oxidation. The influence of operational variables — O3, H2O2, Mn2+ and Fe2+ concentrations and reaction time were investigated. Researches were carried out on aqueous solution of FA, which concentration was 500 mg/l. Fenton process was investigated at pH 3 and catalytic ozonation at pH 7, 10 and 12. Results revealed that Fenton process was much more effective in FA degradation than catalytic ozonation with Mn2+ as a catalyst. The optimal H2O2/Fe2+ dosage for a Fenton process was 2000/1000 mg/l. COD and FA concentrations were reduced 59,6% and 79,5%. In case of catalytic ozonation with Mn2+ the eff ectiveness was much less and it was the biggest at pH 12 and Mn2+ dosage 25 mg/l where COD and FA concentration were reduced 14% and 38%. Therefore, Fenton process can be promising technology for FA wastewater pretreatment.