Solar Advanced Oxidation Processes Using Parabolic Trough Concentrators: A Mini-Review

Solar advanced oxidation processes (AOPs) utilising parabolic trough concentrators (PTCs) present a promising approach for the sustainable removal of recalcitrant contaminants from wastewater. This mini-review critically evaluates 25 peer-reviewed studies employing PTC-AOP systems for the degradation of chemical pollutants and microbial pathogens. Reported applications include photolysis, photo-Fenton and photocatalysis for the treatment of synthetic dyes, contaminants of emerging concern, industrial effluents, heavy metals and pathogenic microorganisms. A performance-oriented comparison based on normalised indicators is introduced. The time required for one order-of-magnitude reduction (corresponding to 90% removal; τ90) reveals a significant mineralisation setback, where parent-compound degradation outpaces total organic carbon removal. The PTC concentration ratio and photon utilisation metrics highlight substantial variability in reactor design (geometry, materials, optical performance), which directly influences the treatment kinetics. Overall, PTC-AOP systems demonstrate strong potential as a polishing step within hybrid wastewater treatment. Future research should prioritise the standardisation of performance metrics, the catalyst design suited for high-photon and -temperature operation, and the integration into scalable and climate-resilient solar wastewater treatment.