Evaluation of sodium hypochlorite and peracetic acid for disinfection of synthetic hospital wastewater

This study aimed to evaluate the disinfection of synthetic hospital wastewater using sodium hypochlorite and peracetic acid, with and without the addition of the antibiotic amoxicillin. A full factorial experiment with 2 levels and 4 factors (disinfectant type, presence of amoxicillin, disinfectant concentration, and contact time) was applied to systematically assess the impact of these variables on disinfection efficiency. Based on concentrations commonly detected in hospital effluents, 23.58 mg L −1 of amoxicillin was added to simulate pharmaceutical contamination. The evaluation focused on the efficiency of both disinfectants in removing Escherichia coli from wastewater contaminated at 10 5 CFU mL −1 . Sodium hypochlorite and peracetic acid were tested at concentrations of 5 and 15 mg L −1 and contact times of 5 and 15 min. Physicochemical parameters such as chemical oxygen demand, pH, total residual chlorine, and total residual peracetic acid were measured alongside microbiological assessments. The novelty of this study lies in the assessment of disinfection performance in the presence of a pharmaceutical compound, representing real hospital wastewater scenarios. Peracetic acid demonstrated effective Escherichia coli inactivation, presenting a viable alternative to sodium hypochlorite with potentially lower by-product formation. However, specific by-products like acetic acid and hydrogen peroxide from peracetic acid decomposition were not quantified and are recommended for future studies. Among the tested conditions, peracetic acid at 15 mg L −1 is recommended for extended disinfection, efficient microorganism reduction, with potentially lower toxic by-products. The study also offers insights into byproduct formation and economic considerations of each disinfectant, providing supporting information for decision-making in hospital wastewater management.