Treatment of biorecalcitrant α-methylphenylglycine aqueous solutions with a solar photo-Fenton-aerobic biological coupling: Biodegradability and environmental impact assessment

The photo-Fenton process under solar irradiation (SPF) was coupled to an aerobic activated sludge biological treatment carried out in a sequencing batch reactor (SBR). The effectiveness of the coupling for the treatment of aqueous solutions polluted with non-biodegradable α-methyl-phenylglycine (α-MPG) was evaluated. Respirometry was chosen as alternative to other conventional tests (BOD5/COD, Zahn-Wellens, Microtox®) for the quantification of both biodegradability and toxic/inhibitory effect of the polluted water along the SPF time, the final goal being the determination of the suitable reaction time for chemical–biological coupling. The nitrification of the aqueous solution during the biological treatment, a process that might take place at the same time than the oxidation of organic matter and endogenous respiration, was evaluated along the different SBR cycles. Finally, a comparative life cycle assessment (LCA) of SPF and an integrated chemical–biological coupling (SPF–SBR) was carried out in order to identify the best alternative, from an environmental point of view, for the treatment of biorecalcitrant pollutants. The determination of the main impact factors of the biological treatment was also carried out. The results of the bench-scale study indicate that both the SPF and SPF–SBR treatments are environmentally friendly and effective alternative strategies for the treatment of water loaded with non-biodegradable compounds.

• Photo-Fenton coupled to a biological treatment for removal of non-biodegradable pollutant.
• Respirometry used for determination of reaction time for chemical-biological coupling.
• Life cycle assessment of chemical-biological coupling to identify the best alternative.