Continuous discharges from diverse industrial activities have severely degraded the water quality of the Lerma River, turning it into a major environmental, social, and public health concern. Conventional wastewater treatment processes are often insufficient for eliminating persistent and refractory organic pollutants; therefore, the implementation of advanced oxidation processes (AOPs) is increasingly required to restore water quality. In this context, the present study systematically evaluated the individual and combined effects of ozonation and electrochemical oxidation using boron-doped diamond (BDD) electrodes for the treatment of contaminated river water. Ozonation alone achieved an 89% reduction in turbidity and a 19% decrease in total organic carbon (TOC), while electrochemical oxidation reduced turbidity by 82% and TOC by 57%. Remarkably, the simultaneous application of both treatments resulted in a 98% reduction in turbidity and an 80% decrease in TOC, clearly demonstrating a strong synergistic effect. Regarding true color at 436 nm, associated with yellow chromophore compounds, removal efficiencies of 98.9%, 94.7%, and 67.3% were obtained for the combined process, electrochemical oxidation, and ozonation, respectively. Phytotoxicity tests with Lactuca sativa seeds showed no statistically significant difference in toxicity in water treated with the O₃–EO System compared to raw water. These results highlight, for the first time under real river water conditions, the superior performance of the integrated O₃–EO system as an effective strategy for the intensified degradation and partial mineralization of persistent organic contaminants, thereby underscoring its strong potential for advanced remediation of heavily polluted surface waters.

During wastewater treatment (WT), sewage sludge (SS) is produced containing organic matter and pathogenic microorganisms that represent health risks so it must be stabilised. Several authors have reported secondary SS (sludge from the bioreactor for WT) stabilisation for its use in soil as fertiliser, but to date primary SS (sludge from primary settler or chemical precipitation tank in WT) is not exploited. In this study, we applied sonication and electrooxidation on primary SS in order to reduce the concentrations of total coliforms, fecal coliforms (FC), and chemical oxygen demand (COD). Here, we show that sonication, compared with electrooxidation, decreases twice as much FC in wastewater SS, and the process is influenced by the interaction of time and applied pH. Also, the interaction of pH and the current intensity influence the decrease of FC and COD in the treated primary SS by electrooxidation. Our results demonstrate that the application of sonication with pH 5 for 10 minutes decreases the concentration of FC by 31% in the primary sludge, compared to untreated sludge. It is necessary to apply complementary treatments in order to further reduce the concentrations of pathogenic microorganisms.