Removal of nalidixic acid and its degradation products by an integrated MBR-ozonation system

• Published in: Journal of hazardous materials Vol. 203; pp. 46 - 52
• Main Authors: Pollice, A., Laera, G., Cassano, D., Diomede, S., Pinto, A., Lopez, A., Mascolo, G.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.02.2012
• Subjects: biodegradable products; Bioreactors; chemical oxygen demand; Concentration (composition); Crack opening displacement; Degradation; Integrated process; Membrane bioreactor; nalidixic acid; Nalidixic Acid - isolation & purification; oxidation; Ozonation; Ozone; Ozone - chemistry; Pharmaceutical wastewater; Polishing; Salinity; sodium acetate; Spreads; streams; synergism; Waste water; wastewater; Ozonation; Membrane bioreactor; Pharmaceutical wastewater; Integrated process; Salinity
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2011.11.072

► Degradation of the antibacterial nalidixic acid was obtained by integrated MBR-ozonation. ► Synergistic effects of chemical oxidation and bioprocesses were exploited. ► Ozonation oxidized target compound into biodegradable products that were then removed by MBR. ► Ozonation caused no relevant drawbacks to biological and filtration processes in the MBR. ► Integrated process was more efficient than sequential configuration. Chemical–biological degradation of a widely spread antibacterial (nalidixic acid) was successfully obtained by an integrated membrane bioreactor (MBR)-ozonation process. The composition of the treated solution simulated the wastewater from the production of the target pharmaceutical, featuring high salinity and a relevant concentration of sodium acetate. Aim of treatment integration was to exploit the synergistic effects of chemical oxidation and bioprocesses, by adopting the latter to remove most of the COD and the ozonation biodegradable products. Integration was achieved by placing ozonation in the recirculation stream of the bioreactor effluent. The recirculation flow rate was three-fold the MBR feed, and the performance of the integrated system was compared to the standard polishing configuration (single ozonation step after the MBR). Results showed that the introduction of the ozonation step did not cause relevant drawbacks to both biological and filtration processes. nalidixic acid passed undegraded through the MBR and was completely removed in the ozonation step. Complete degradation of most of the detected ozonation products was better achieved with the integrated MBR-ozonation process than using the sequential treatment configuration, i.e. ozone polishing after MBR, given the same ozone dosage.