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The use of the Fenton's process for the depuration of a post-biological treated milk whey wastewater was studied, aiming to achieve adequate operational conditions for a cost effective treatment to generate a suitable effluent to be directly discharged into the natural water courses. A design of experiments was implemented in order to understand the role of the independent parameters and their combinations over the treatment process. From our results the hydrogen peroxide concentration and the ratio between [H 2 O 2 ]:[Fe 2+ ] as well as their interaction were statistically important concerning both TOC and COD removal. The experiments performed at the highest value of [H 2 O 2 ] and at the lowest level of [H 2 O 2 ]:[Fe 2+] lead to effluents accomplishing the environmental legislation. Moreover, toxicological tests revealed that the treated effluent was harmless to the ecosystems. A cost estimation analysis was performed and the catalytic activity of the remaining sludge from the homogeneous process was checked. This activity decreases with the number of reuses which reduces the possibility of the direct utilization of the sludge.

The aims of the present work were to assess the application of a chemical process to degrade a mixture of parabens and determine the influence of a natural river water matrix on toxicity. Model effluents containing either a single compound, namely methylparaben, ethylparaben, propylparaben, butylparaben, benzylparaben or p-hydroxybenzoic acid, or to mimic realistic conditions a mixture of the six compounds was used. Fenton process was applied to reduce the organic charge and toxic properties of the model effluents. The efficiency of the decontamination has been investigated using a chemical as well as a toxicological approach. The potential reduction of the effluents' toxicity after Fenton treatment was evaluated by assessing (i) Vibrio fischeri luminescence inhibition, (ii) lethal effects amongst freshwater Asian clams (Corbicula fluminea), and (iii) the impact on mammalian neuronal activity using brain slices. From the environmental point of view such a broad toxicity analysis has been performed for the first time. The results indicate that Fenton reaction is an effective method for the reduction of chemical oxygen demand of a mixture of parabens and their toxicity to V. fischeri and C. fluminea. However, no important differences were found between raw and treated samples in regard to mammalian neuronal activity.

New iron−copper based solids prepared by coprecipitation had their efficiency in the heterogeneous Fenton process investigated regarding organic charge removal and biodegradability enhancement. Different molar proportions between the two metals were used to assess the best one. Chemical oxygen demand (COD), total phenolic content (TPh), and biochemical oxygen demand in 5 days (BOD 5 ) were the parameters used for the evaluation. Two solutions simulated olive mill wastewaters: one comprising six phenolic acids and another containing one extra acid. The efficiency of each catalyst was compared when facing both mixtures, and the one containing more phenolic acids was further decomposed, maybe due to a cooxidation synergistic effect related with the presence of more radicals. All solids proved to be fit for the reaction, and the Fe− Cu−O 50/50 catalyst showed the best overall results regarding organic charge removals.

Fenton’s reaction is an advanced oxidation process where, classically, hydrogen peroxide is the oxidizing agent and an iron catalyst promotes the formation of hydroxyl radicals (•OH). Among the studies that evaluated different metals as Fenton-like catalysts, our group of investigation has recently used cerium-based solids as heterogeneous catalysts in slurry reaction and, in this work, iron sludge coming from an industrial Fenton’s reactor used for the wastewater depuration of a detergent production factory is being appraised while treating a synthetic effluent containing 0.1 g.L