Photochemical elimination of phenols and COD in industrial wastewaters

Abstract

It is demonstrated that toxic pollutants such as phenols in industrial wastewaters can be eliminated efficiently by photochemical methods using a combination of UV and heterogeneous photocatalyst, and combinations of UV, H2O2, and ferric compounds. The combination of UV and photocatalyst even decreases the COD of some of the toxic industrial wastewater around 60-70% in 1-4 hour treatment time depending on the source of the wastewater. The different combinations of UV (200 W high pressure mercury lamp, wavelength 313 ≤ λ ≤ 456 nm), magnetite or aluminium oxide (as photocatalyst), H2O2 and iron compounds (FeCl3, Fe(NH3)2(SO4)2, as Fenton reagent) were used in lab scale experiments to examine the elimination at aerated conditions of pure phenol in solutions (initial concentration = 25 ppm) and of substituted phenols and COD in industrial wastewaters originally from phenolic resin manufacture, oil refinement, shale oil dry distillation, and naphthenic acid production. The results clearly show the separate and combined effect of UV, Ferric compounds and H2O2 on the elimination of phenols and COD.