Electrochemical oxidation of a membrane-distillation concentrate for the treatment of real pharmaceutical wastewater.

This study presents the first investigation of the electrochemical oxidation of a real membrane-distillation (MD) concentrate for the integrated treatment of highly concentrated pharmaceutical wastewater (PWW). The coupling of electro-Fenton and anodic oxidation applied to a real MD retentate, concentrated by a factor of 1.6 compared to the original PWW, reduced the total organic carbon (TOC) concentration from 23,460 to 12,199 mg/L in 24 h (mineralization efficiency of 48%). The pharmaceutical linezolid (LIN), which appeared in concentrated form in the MD retentate, was completely removed below the detection limit in the process (>99% of LIN degradation within the first 90 min of operation). Despite the high initial toxicity of the retentate, the electrochemical process successfully reduced the toxicity associated with LIN and other organic compounds in the retentate. The energy requirements, normalized to the TOC content, were determined for both the MD (0.056 kWh/g) and the electrochemical (0.016-0.020 kWh/g) processes and proved competitive when compared to alternative treatment options for highly concentrated effluents, such as incineration or supercritical water oxidation. In conclusion, the results showcase the potential of combining MD and electrochemical oxidation for sustainable PWW treatment.