Title : Wastewater treatment by advanced oxidation process (Hydrodynamic cavitation)
Abstract:
The discharge of synthetic dyes into water bodies from textile industries represents a persistent environmental challenge due to their high chemical stability, toxicity, and resistance to conventional degradation methods. Among these, Aniline Blue, a triphenylmethane dye, is particularly problematic because of its carcinogenic and mutagenic potential, and its ability to persist in the environment. Traditional wastewater treatment processes, including biological oxidation, coagulation, membrane separation, and adsorption, are limited by long treatment times, incomplete mineralization, sludge formation, and high operating costs. To overcome these challenges, advanced oxidation processes (AOPs) have gained increasing attention for their ability to generate highly reactive hydroxyl radicals that effectively mineralize complex organic contaminants. In this study, hydrodynamic cavitation (HC) was investigated as a promising AOP for the treatment of Aniline Blue dye from synthetic wastewater, with hydrogen peroxide (H?O?) employed as an additional oxidizing agent to enhance degradation efficiency.
Experiments were carried out using a 2 HP hydrodynamic cavitation setup operated at 5 bar pressure with treatment durations of 60 minutes. Systematic optimization of process parameters was performed, with a focus on pH control and H?O? dosage. The pH of the solution was adjusted to acidic, neutral, and alkaline conditions, while oxidant concentration was varied between 0.5–2 mL/L. Degradation efficiency was assessed through Chemical Oxygen Demand (COD) analysis. Results clearly indicated that acidic conditions significantly improved degradation performance, with COD values reduced from 272 mg/L at pH 7 to 80 mg/L at pH 2.5, corresponding to a 70.6% reduction. Furthermore, the combination of HC with H?O? displayed a strong synergistic effect, achieving up to 95% decolorization and 97% COD reduction under optimal conditions (pH ≈ 2.5; H?O? dosage of 1–2 mL/L). Additional studies revealed that lower dye concentrations enhanced overall COD removal, while higher H?O? dosages increased hydroxyl radical production but required careful control to avoid unnecessary chemical input.
This research demonstrates that the HC–H?O? hybrid process is a sustainable, cost-effective, and scalable treatment option for refractory dye effluents. Unlike conventional methods, this approach produces minimal sludge, requires inexpensive reagents, and can be integrated into existing treatment facilities. The findings also highlight key factors influencing efficiency, such as acidic pH and optimized oxidant dosage, which can guide future industrial-scale applications. While challenges related to reactor scale-up, pump energy consumption, and process economics remain, the study provides strong evidence that HC, coupled with oxidizing agents, represents a viable pathway for environmentally responsible textile wastewater treatment in line with regulatory compliance and green engineering practices.
