Wastewater containing mainly 5-amino-6-methyl-2-benzimidazolone (AMBI), used in the manufacture of dyes, was characterized as bio-recalcitrant by means of different biodegradability tests. In order to enhance the biodegradability of this important pollutant, solar photocatalytic degradation methods were explored. The systems light/TiO2/O-2, light/TiO2/H2O2, light/Fe3+/O-2 and light/Fe3+/H2O2 were compared under direct sunlight at the Plataforma Solar de Almeria (Spain), using a Compound Parabolic Collector (CPC). The iron photo-assisted systems exhibited the most interesting behaviour, from the kinetic and engineering points of view, especially if their combination (as pre-treatment) with a biological process is considered. To compare the efficiency of these systems, the evolution of the following parameters were studied: (a) the dissolved organic carbon and initial compound concentration, (b) the toxicity, and (c) the biodegradability of treated solution. At lab scale, using a solar lamp, the degradation rate of the system light/Fe3+/H2O2 was two times higher than the system light/Fe3+/O-2 but this last system does not need H2O2 addition, improving the economical requirements of the system. (C) 2003 Elsevier Ltd. All rights reserved.
César Pulgarin, Stefanos Giannakis, Giulio Farinelli, Ogadimma Cassandra Oji-Okoro