Photodegradation of EDTA using Fenton's reagent: a pilot-scale study

The presence of ethylenediaminetetraacetic acid (EDTA) in decontamination wastes can cause complexation of cations resulting in interferences in their removal by various treatment processes, for example chemical precipitation, ion exchange, etc., and can negatively affect the quality of the final form of the waste. Advanced oxidation processes using ozone, H2O2, ultrasonics (US), ultraviolet (UV) light, Fenton's reagent (Fe(II) + H2O2), alone or in combination, are regarded as possible methods of clean and ecologically safe remedial treatment for the degradation of organics. In this study, the development of a column photoreactor (15 L) and a shallow-tank photoreactor (100 L) was carried out at the Centralised Waste Management Facility, Kalpakkam, India. Pilot-scale (batch) studies of the photocatalytic degradation of EDTA (20,000 mg/L) using UV + Fenton's reagent in these reactor geometries were attempted. The effect of the power of the UV radiation on the kinetics of photodegradation of EDTA (20,000 mg/L) was studied using the column photoreactor. The shallow-tank reactor was used to study the photodegradation of EDTA (20,000 mg/L) using UV radiation, visible radiation, and sunlight. The successful use of sunlight as a source of energy and its greater effectiveness than UV radiation in the treatment of EDTA are presented.