An eco-friendly hybrid sonophotocatalytic approach to optimize carpet washing wastewater treatment

The fundamental objective of this work is to examine the efficiency of the hybrid advanced treatment process for removal of residual organic pollutants in carpet washing wastewater at various reaction conditions. For this goal, Taguchi method was adopted to optimize the critical factors viz. catalyst type (TiO2 and ZnO), catalyst concentration (0.5–2.5 g/L), pH (2–10), H2O2 concentration (0–10 mM), and operation time (30–180 min). These experimental factors were handled in mixed levels (21 × 34), and operation parameters were optimized by the application of L18 tests. The analysis of variance results showed that catalyst type, H2O2 concentration, and pH had the highest effects on the elimination of chemical oxygen demand (COD) and color. COD and color removal efficiencies were determined as 53% and 99%, which are close to the predicted values of 49% and 95%, respectively, according to the confirmation test carried out under optimal parameters. Thus, considering the cost of energy consumed and acceptably high COD and color removal level, the sonophotocatalysis process combining ultrasound, ultraviolet, hydrogen peroxide, and catalyst (TiO2 and ZnO) could achieve great performance for the reduction of pollution load in wastewater by the fast and eco-friendly removal of organic pollutants from carpet washing effluents.