Enhanced photocatalytic NOM removal in photo-assisted coagulation-flocculation process using TiO2 nano-catalyst coated on settling tank

A new system to remove natural organic matter from water can considerably decrease the risk of hazardous by-product formation was designed. In this study, the settling process in water treatment plants was upgraded using Titanium dioxide nanoparticles coated on the inner side of the settling tank using the dip-coating method to eliminate total organic carbon. The FESEM and EDX analysis of the immobilized Titanium dioxide layer indicated homogenous dispersion of Titanium dioxide on Sekurit glass. Furthermore, the Raman and FTIR spectrum of the modified surface represented the specific Raman bands and surface functional groups of Titanium dioxide, respectively. The experiments were conducted under different UV irradiation (8, 16, and 24W) to evaluate the photocatalytic activity of Titanium dioxide to enhance the coagulation-flocculation process. The experiment carried out using 24 W UVa lamps for 180 min was able to remove 95% of turbidity and total organic carbon. The conventional method removed just about 33% of total organic carbon in the same treatment process showing inefficiency to achieve drinking water standards. However, the treated water in the enhanced photocatalytic system achieved drinking water standard according to EPA(total organic carbon < 2 mg/L). The enhanced photocatalytic degradation followed the pseudo-first-order reaction kinetics with a correlation coefficient of (R-2 > 0.99). Performing experiments in different settling cycles demonstrated good stability of Titanium dioxide coated layer, and the removal efficiency reduced 6% after five cycles, establishing the proposed method is practical and also much more efficient.