Effect of Flocculation as a Pretreatment to Photocatalysis in the Removal of Organic Matter from Wastewater

Effects of different flocculants (chloride-based salts and ferric and ferrous salts) and initial organic concentration of wastewater on flocculation-photocatalysis hybrid process were investigated. Titanium Dioxide (TiO2) adsorption alone, flocculation alone, flocculation followed by TiO2 adsorption, photocatalysis alone, and flocculation followed by photocatalysis removed 60%, 72%, 80%, 85%, and 92% of dissolved organic matter, respectively. The effect of photo-Fenton reaction in removing organic matter was found to be marginal on the flocculation-photocatalysis hybrid system. The organic removal with the flocculation-photocatalysis hybrid system showed similar results for different flocculants such as chloride-based salts, ferric and ferrous salts and there is no comparative beneficial effect. Flo culation followed by photocatalysis removed up to 92% of organic matter. Different initial concentrations of organic matter were significantly reduced by flocculation to a low level before loading to the photocatalysis process.