Advanced oxidation processes by UV/H2O2 for the removal of anionic surfactants in a decentralized wastewater treatment plant in Ecuador

Abstract

Surfactants are persistent pollutants that pose risks to ecosystems and human health due to their low removal efficiency in conventional wastewater treatment plants. In Guayaquil, Ecuador, a decentralized facility discharges water with a surfactant concentration that exceeds the national legislation up to 20 times. This work aims to demonstrate the effectiveness of the advanced oxidation process UV/H2O2 in removing anionic surfactants as a tertiary treatment for the decentralized facility investigated. A laboratory-scale batch system was tested for the treatment of real effluent with three hydrogen peroxide concentrations (100, 250, and 500 mg L−1) and UV exposure up to 120 min. All experimental trials were run in duplicate. After 60 min of UV exposure with 250 mg L−1 of H2O2, the anionic surfactant removal was 94.3 + 4.3%, and the effluent complied with the discharge limits (,0.5 mg L−1). These operational parameters were selected for continuous laboratory-scale experiments to simulate the facility operation, achieving a maximum removal of 92.3 + 2.5%. Although the reactor demonstrates a high removal rate, improvements to its configuration are necessary to meet discharge limits. The UV/H2O2 process allowed the removal of anionic surfactants, suggesting its feasibility as a complementary treatment in decentralized plants with similar problems.