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R. Sukanya Devi et al.
• This can be operated over a wide range of solar radiation spectrum.
When compared with chemical Fenton process, the photo-Fenton has many advantages such as reduction in dosage of catalyst resulting in reduced sludge formation but
the cost of UV lamps, longer time for UV irradiation and higher energy consumption
are the major drawbacks of this process [56].
3.5.3 Sono-Fenton Process
The sound waves with the frequency higher than the upper limit of human ears
(above 20,000 Hz) are known as ultrasonic sound waves. These sound waves create
expansion and compression cycles, and during expansion cycle, it creates acoustic
cavitation. These cavities oscillate in size, following the frequency cycles created by
ultrasonic sound waves. At certain condition, the cavitation bubble undergoes implosion, creates increase in hundreds of atmospheric pressure and thousands of temperature measured in Kelvin. When ultrasonic sound waves are applied to wastewater
treatment system, it decomposes the organic contaminants either by free hydroxyl
radicals formed by pyrolysis or by pyrolytic cleavage.
The combination of Fenton reagent and ultrasound is known as the sono-Fenton
treatment process which promises high efficient degradation of organics. Ultrasound
creates higher hydroxyl radical due to cavitation and explosion of the water molecule
which enhances the Fenton oxidation rate. In addition to the generation of hydroxyl
radical, ultrasound enhances constant stirring and mass transfer effects so as to
diffuse the reactants in the solution and improves the efficacy of Fenton reaction. The
limitations of sono-Fenton process are its high cost and energy intensive process.
3.5.4 Fenton-Like Process
Fenton-like processes use zero valent iron instead of ferrous sulphate and are classified as heterogeneous and homogeneous Fenton-like processes. Adding a suitable
solid catalyst to the Fenton reagent replaces Fe
2+ and forms heterogeneous Fentonlike processes. The use of combination of other metal ion or metal ion-organic
ligand complexes and hydrogen peroxide are termed as homogeneous Fenton-like
processes. Since the Fenton-like systems show a significant result in terms of efficient degradation of organic pollutants and reduction in sludge generation, the various
process parameters like pH, hydrogen peroxide concentration, catalyst concentration,
etc., are studied extensively [57].
R. Sukanya Devi et al.
• This can be operated over a wide range of solar radiation spectrum.
When compared with chemical Fenton process, the photo-Fenton has many advantages such as reduction in dosage of catalyst resulting in reduced sludge formation but
the cost of UV lamps, longer time for UV irradiation and higher energy consumption
are the major drawbacks of this process [56].
3.5.3 Sono-Fenton Process
The sound waves with the frequency higher than the upper limit of human ears
(above 20,000 Hz) are known as ultrasonic sound waves. These sound waves create
expansion and compression cycles, and during expansion cycle, it creates acoustic
cavitation. These cavities oscillate in size, following the frequency cycles created by
ultrasonic sound waves. At certain condition, the cavitation bubble undergoes implosion, creates increase in hundreds of atmospheric pressure and thousands of temperature measured in Kelvin. When ultrasonic sound waves are applied to wastewater
treatment system, it decomposes the organic contaminants either by free hydroxyl
radicals formed by pyrolysis or by pyrolytic cleavage.
The combination of Fenton reagent and ultrasound is known as the sono-Fenton
treatment process which promises high efficient degradation of organics. Ultrasound
creates higher hydroxyl radical due to cavitation and explosion of the water molecule
which enhances the Fenton oxidation rate. In addition to the generation of hydroxyl
radical, ultrasound enhances constant stirring and mass transfer effects so as to
diffuse the reactants in the solution and improves the efficacy of Fenton reaction. The
limitations of sono-Fenton process are its high cost and energy intensive process.
3.5.4 Fenton-Like Process
Fenton-like processes use zero valent iron instead of ferrous sulphate and are classified as heterogeneous and homogeneous Fenton-like processes. Adding a suitable
solid catalyst to the Fenton reagent replaces Fe
2+ and forms heterogeneous Fentonlike processes. The use of combination of other metal ion or metal ion-organic
ligand complexes and hydrogen peroxide are termed as homogeneous Fenton-like
processes. Since the Fenton-like systems show a significant result in terms of efficient degradation of organic pollutants and reduction in sludge generation, the various
process parameters like pH, hydrogen peroxide concentration, catalyst concentration,
etc., are studied extensively [57].