A textile waste water treatment system using photocatalytic reactor and catalyst recycle unit

Abstract

A photocatalytic system for wastewater treatment from textile industries was constructed and tested for its efficiency. The system consisted of two units - a photoreactor for dye decomposition and a catalyst recovery unit. The photoreactor was an annular plug flow photoreactor under irradiation of 36 W Toshiba blacklight. The catalyst recovery unit was 42 L of sediment tank for TiO2 catalyst recovery. In our study, a Cibra Cron red R-W 150% (an anionic azo dye) was used to prepare a synthetic textile wastewater. The experimental parameters such as flow rate, pH, dye initial concentration, catalyst loading and setteled time that affected the system performance were investigated. The photodegradation kinetics were found to follow the Langmuire - Hinshelwood model and also depended on the TiO2 concentration and the pH. The optimum condition for photocatalytic decomposition was at pH 3 and at 1 g/L of TiO2 catalyst loading. The reaction rate constant, k and the adsorption constant, K for the scale-up photoreactor were 3.345 mg/L-min and 0.0204 L/mg, respectively. For the catalyst recycle unit, the overflow and underflow concentration of the TiO2 catalyst were 2.00 and 0.002 mg/L, respectively, at 100 ml/min of inlet flow rate, 50 ml/min of overflow and 50 ml/min of underflow.