Natural chelating agents from olive mill wastewater to enable photo-Fentonlike reactions at natural pH

The potential of polyphenols, present in olive mill wastewater (OMW), to act as iron chelators in photo-Fenton reaction without water acidification for the treatment of different microcontaminants in water has been studied. OMW containing 6.3 g/L of phenols has been dosed from 1: 100 to 1: 1500 in water containing 200 mu g/L of terbutryn, chlorfenvinphos, pentachlorophenol and diclofenac. Experiments were performed in compound parabolic collector (CPC) solar pilot plant installed in Plataforma Solar de Almeria using Fe 0.1 mM and H2O2 50 mg L-1. The total irradiated area was 3.08 m(2) and the total volume 39 L. Results indicated that iron was forming a stable complex with components of OMW along different pH values. > 90% degradation of the four microcontaminants was achieved with solar photo-Fenton at circumnetutral pH adding OMW 1: 1200 for keeping iron in solution, allowing to operate a photo-Fenton process without acidifying wastewater. It leads to an alternative to using artificial-synthetic iron-complexing ligands.