Microwave and Fenton's reagent oxidation of wastewater

Abstract

We compared two H 2 O 2 oxidation methods for the treatment of industrial wastewater: oxidation using Fenton's reagent [H 2 O 2 /Fe(II)] and microwave irradiation. Both methods were applied to the treatment of synthetic phenol solutions (100 mg L −1 ) and of an industrial effluent containing a mixture of ionic and non-ionic surfactants at high load (20 g L −1 of COD). The effects of initial pH, initial H 2 O 2 concentration, Fenton catalyst amount and irradiation time were assessed. According to the oxidation of phenol, it has been found that the oxidation by Fenton's reagent is dependent on the pH, contrary to the microwave system, which is not influenced by this parameter. For both systems, a limiting amount of oxidant has been found; above this point the oxidation of phenol is not improved by a further addition of peroxide. The oxidation of the industrial surfactant effluent has only been successful with the Fenton's reagent. In this case, large amounts of ferrous ions are necessary for the precipitation of the ionic surfactants of the effluent, followed by the oxidation of the non-ionic constituents of the solution.

Experimental Design of Photo-Fenton Reactions for the Treatment of Car Wash Wastewater Effluents by Response Surface Methodological Analysis

“…Examples of 2 Advances in Environmental Chemistry AOPs include the use of hydrogen peroxide with ultraviolet light (H 2 O 2 /UV) to treat hazardous compounds [7], Fenton and photo-Fenton reagent (H 2 O 2 /Fe 2+ ) [8][9][10], semiconductor photocatalysis [11], and the sonolysis process using ultrasonic irradiation [12]. Among various AOPs, the Fenton reagent is one of the most effective methods for treating various industrial effluents including wastewater [13,14] and oily wastewater [15]. Previous work by the authors has involved the application of Fenton and the photo-Fenton reagents for the treatment of water polluted with diesel oil emulsion [10,16].…”

Microwave Irradiation as a Way to Reutilize the Recovered Struvite Slurry and to Enhance System Performance

“…Electro-magnetic vibration of microwave enhances the hydrolysis and also increases the temperature within a short time that helps to reduce ammonia. Sanz et al (2003) stated that microwave heating was much higher than that of ordinary heating at the same conditions which enhance the oxidation and rate of reaction. Microwave irradiation reduced the heating time by its molecular vibration and dissociated the complex molecule into simpler form within a short time.…”

“…High temperature with vibration also could induce the dissolution. Sanz et al (2003) showed that microwave irradiation dissociates the hydrogen peroxide and generates hydroxyl radicals due to the excitation of the molecule to high vibrational and rotational energy levels. Break down of MAP crystals occurred due to this high vibrational and rotational energy.…”

Advanced Oxidation Processes for Food Industrial Wastewater Decontamination

“…These processes involve the generation of highly free radicals, mainly hydroxyl radical (HO • ) The application of AOP`s in wastewater treatment leads to the degradation of the pollutant rather than transferring it to another phase, making the relevant technologies effective in the removal of organic pollutants in solution. In recent years, one of the main objectives of these processes mainly with highly polluted effluents has been not to mineralise the pollutant totally (AOP`s for complete mineralization are very expensive), but to improve the biodegradability for a possible coupling of the AOP`s with a conventional biological treatment process [Sanz et al 2003, Muñoz et al 2005]. …”