Sulfamethoxazole abatement by photo-Fenton toxicity, inhibition and biodegradability assessment of intermediates.

The objective of this work was to study the abatement of 200mgL(-1) sulfamethoxazole (SMX) solution by means of photo-Fenton process. Biodegradability of the treated solutions was followed by the ratio biochemical oxygen demand at five days/chemical oxygen demand (BOD(5)/COD) and toxicity by Microtox and inhibition tests. Experiments with different initial concentration of H(2)O(2) were carried out. The initial amount of Fe(2+) and pH of the solution were set at 10mgL(-1) and 2.8 respectively. The temperature of the reactor was kept constant in all the experiments (25+/-0.8 degrees C). Photo-Fenton process is thought to be a successful treatment step to improve the biodegradability of wastewater containing SMX. The complete antibiotic removal was achieved for a H(2)O(2) dose over 300mgL(-1). Biodegradability (BOD(5)/COD) rose from zero (SMX solution) to values higher than 0.3 (treated solutions). Toxicity and inhibition tests pointed out in the same direction: oxidized intermediates for initial H(2)O(2) dose over 300mgL(-1) showed no toxicity effects on pure bacteria and no inhibition on activated sludge activity.