A coupled solar photocatalytic-biological pilot plant system has been employed to enhance the biodegradability and complete mineralization of a biorecalcitrant industrial compound, alpha-methylphenylglycine, dissolved in distilled water and simulated seawater at 500 mg L-1. The pollutant was completely degraded by a solar photo-Fenton treatment in a 75-L pilot plant made up of four compound parabolic collector (CPC) units. The catalyst concentration employed was 2 and 20 mg L-1 of Fe2+ and the H2O2 concentration was kept in the range of 200-500 mg L-1. A Zahn-Wellens (Z-W) test applied to photo-treated samples demonstrated that intermediates produced within a short time of starting the photo-Fenton process were biodegradable. Consequently, the photocatalytic and biological processes were combined. Biodegradable compounds generated during the preliminary oxidative process were biologically mineralized in a 170-L aerobic immobilised biomass reactor (IBR), filled with 90-95 L propylene Pall (R) Ring supports colonized by activated sludge. Almost total mineralization (90% overall total organic carbon removed) was attained in the combined treatment system (for both distilled and seawater experiments). Moreover, nitrification and denitrification phenomena were also observed. (c) 2007 Elsevier B.V. All rights reserved.