Effluent treatment: detergent removal using Fenton ultrasound process and reused nail

ABSTRACT

Different methodologies are described in the literature for the industrial effluents treatment. However, most processes are not fully efficient when the effluent has low suspended colloidal particle content and high concentration of organic matter and detergents. Among the methods that are studied to eliminate detergent and organic matter from industrial effluents, the Fenton process is an attractive strategy. In the present study, a more sustainable methodology was applied to remove detergent and organic matter from liquid effluents using Fenton process with ultrasound and recycled nail. The optimization of parameters for effluent treatment was carried out through the analysis of pH, detergents, color, turbidity, chemical oxygen demand, biochemical oxygen demand, oils and greases, and suspended solids. The best results were obtained at pH 3.5, with 90 mg L⁻¹ of hydrogen peroxide and an iron nail (2.7 g) both for the Fenton process and Fenton with ultrasound. Under these conditions, detergent removal values were 99.4%. At pH 2.5, 4.5, and 5.5, the values obtained for detergent removal were lower, 75.2, 89.5, and 68.4%, respectively. Similar results were obtained for color, turbidity, chemical oxygen demand, and biochemical oxygen demand. The reuse of the nails showed that the average detergent removal efficiency up to the fourth cycle was above 90%, and, from the fifth cycle, a gradual decrease was observed, with the difference between the first and sixth cycles being around 10%.

Keywords:
effluents treatment; water pollution; detergents