The use of metallurgical waste for heterogeneous photo Fenton-Like treatment of cosmetic effluent

Cosmetic industry wastewater has undesirable features such as low biodegradability, high levels of suspended solids, fats and oils, and high load of organic matter. The heterogeneous photo Fenton-Like degradation process is an alternative means of treating this wastewater since it has the ability to mineralize organic matter. In addition, waste from the steel/metallurgical industry can be used as a source of iron, by generating less solid waste (sludge) and involving a more cost-effective technology. This study aims to evaluate the heterogeneous photo Fenton-Like treatment before and after the adsorption-desorption equilibrium, by using the metallurgical residue as a catalyst, as well as determining possible organic compounds adsorbed by the generated chemical sludge. The treatment was carried out with metallurgical waste, as a source of iron, in concentrations of 8.0 g L-1, H2O2 0.05 g L-1 and initial pH 3.0 in 6 min of treatment. Under these conditions, it was possible to obtain removals of above 75 % for total organic carbon and 99 % for chemical oxygen demand. The analysis of the residue of the treatment was submitted to TG-FTIR analyses and was determined that at the end of the photo Fenton-Like process after the adsorption process, approximately 10.8 % of the mass of organic matter remained adsorbed onto the residue, which suggested that most of what was present in the cosmetic matrix, had been oxidized. FTIR analyses of the solid sample also revealed that the adsorbed organic compound is possibly paraffin, which corresponds to the type of effluent discharged by the cosmetics industry.