Evaluation of solar photo-Fenton and ozone based processes as citrus wastewater pre-treatments

Abstract

Abstract In the present study, different ozone based processes (O 3 , O 3 /OH − , O 3 /UV, O 3 /H 2 O 2 and O 3 /UV/H 2 O 2 ) and solar photo - Fenton treatment were evaluated for the pre - treatment of synthetic samples of citrus wastewater. The highest removal of organic matter in ozone based processes was achieved at high pH values, using H 2 O 2 and UV radiation at 254 nm. After the application of ozone for 150 min at 1.9 gO 3 /L, 1017 mg/L of H 2 O 2 , UV radiation and pH ∼ 7, the removal efficiency of chemical oxygen demand and dissolved organic carbon was 15.7% and 10.9%, respectively. Apparent color, real color and turbidity were reduced significantly, mainly at the initial stages of the reaction. The solar photo - Fenton treatment (pH of citrus wastewater, [H 2 O 2 ] = 15,937 mg/L, 510 mg/L of Fe 3+ and reaction time of 30 min) produced a removal of 77% of chemical oxygen demand and 53% of dissolved organic carbon. This photocatalytic process is the most appropriate technique for the pretreatment of citrus effluent. An estimation of the total production costs of the photo - Fenton process shows that when solar light is used the cost of the treatment is 13.8 €/m 3 .