Improvement of the photo-Fenton process at natural condition of pH using organic fertilizers mixtures: Potential application to agricultural reuse of wastewater

Abstract

Five organic fertilizers (DTPA, EDDHA, HEDTA, EDTA and EDDS) were studied as iron sources for photo-Fenton process at natural pH to remove micropollutants (MPs) from wastewater for its reuse in irrigation. The results demonstrated that the stability constant of iron chelates is a key parameter for optimal micropollutants removal and it is linked to the structure of chelator. Mixtures of organic fertilizers were also tested to overcome excessive iron loose and to optimize MPs abatement kinetics. An improvement of photo-Fenton process occurred when using chelating mixtures. For instance, with 50%EDDS + 50%EDTA total removal of propranolol (PROP) was achieved at 30 minutes while EDTA needed up to 90 min of reaction and with EDDS total degradation was not achieved. In addition, the availability of dissolved iron of the mixture at the end of the treatment was 5.5 times higher than EDDS, increasing its suitability as reuse water for irrigation.