Improving the biodegradability of hospital urines polluted with chloramphenicol by the application of electrochemical oxidation

• Published in: The Science of the total environment Vol. 725; p. 138430
• Main Authors: Herraiz-Carboné, Miguel, Cotillas, Salvador, Lacasa, Engracia, Moratalla, Ángela, Cañizares, Pablo, Rodrigo, Manuel A., Sáez, Cristina
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10.07.2020
• Subjects: Biodegradability; Chloramphenicol; Electrochemical oxidation; Hospital effluents; Urine; Urine; Chloramphenicol; Hospital effluents; Biodegradability; Electrochemical oxidation
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.138430

This work focuses on improving the biodegradability of hospital urines polluted with antibiotics by electrochemical advanced oxidation processes (EAOPs). To do this, chloramphenicol (CAP) has been used as a model compound and the influence of anodic material (Boron Doped Diamond (BDD) and Mixed Metal Oxide (MMO)) and current density (1.25–5 mA cm−2) on the toxicity and the biodegradability was evaluated. Results show that a complete CAP removal was attained using BDD anodes, being the process more efficient at the lowest current density tested (1.25 mA cm−2). Conversely, after passing 4 Ah dm−3, only 35% of CAP removal is reached using MMO anodes, regardless of the current density applied. Furthermore, a kinetic study demonstrated that there is a clear competitive oxidation between the target antibiotic and the organic compounds naturally contained in urine, regardless the current density and the anode material used. During the first stages of the electrolysis, acute toxicity is around 1% EC50 but it increases once CAP and its organic intermediates have been degraded. The formation and accumulation of inorganic oxidants may justify the remaining acute toxicity. This also helps to explain the trend observed in the rapid biodegradability assays. Finally, a 60% of standard biodegradability (Zahn-Wellens test) was achieved which suggests that electrochemical oxidation with BDD anodes could be the most appropriate technology to reduce the hazard of hospital urines at the operating conditions tested. [Display omitted] •Electrochemical oxidation is suitable to reduce the hazard of hospital urines.•CAP can be completely removed from hospital urines using BDD electrolysis.•MMO-electrolysis leads to partial oxidation of CAP and nil mineralization.•Urine toxicity decreases down to 74% using low current densities.•BDD-electrolysis at low current density increases biodegradability up to 60%.