Detoxification of real pharmaceutical wastewater by integrating photocatalysis and photo-Fenton in fixed-mode

Abstract

The applications of novel Fe-TiO2 composite capable of incorporating in-situ dual effect (photocatalysis and photo-Fenton) have been studied for the treatment of real pharmaceutical effluent using batch and continuous reactors. The treatment time was reduced to a great extent using these novel composite beads along with significant reduction in COD (83%). Coagulation using FeCl3 as a coagulating agent was used as a pre-treatment step prior to in-situ dual process. The parametric optimization in case of in-situ dual process was carried out in batch mode under artificial UV-A irradiations. The biodegradability index (BOD5/COD) of wastewater became 0.71 from 0.172 after 5 h of treatment via in-situ dual process. The intermediates present in the real wastewater before and after the treatment process, were carefully identified through GC–MS analysis based on which a tentative degradation mechanism for the treatment of pharmaceutical wastewater has been proposed. The treated wastewater was found to be completely non-toxic as confirmed through cyto-toxicity as well as acute toxicity analysis. The field-scale applications of fixed-bed in-situ dual process using Fe-TiO2 composite beads were validated from successful treatment (∼80% COD reduction) of real wastewater (5 L) in less than 120 min in a pilot-scale once-though cascade reactor under natural solar irradiations. Moreover, Fe-TiO2 composite beads represented an outstanding recyclability efficiency (>70 recycles) without depicting any significant reduction in their activity as confirmed through various characterization techniques.