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R. Sukanya Devi et al.
(1) electrohydraulic discharge plasma reactors
(2) bubble discharge plasma reactors
(3) gas phase discharge plasma reactors
(4) spray discharge plasma reactors
(5) hybrid plasma reactors.
The classification is based on the total plasma–water interface, and the larger
the interface higher will be the degradation of the organic pollutants. Another
classification of plasma reactors is based on discharge
1. Corona and streamer discharge
2. Glow discharge
3. Dielectric barrier discharge (DBD)
4. Arc discharge.
Out of which, the most used is the pulsed corona discharge and pulsed arc
discharge. Non-thermal plasma can be either applied above the water surface or
applied underwater. Non-thermal plasma interacts with water to generate wide range
of reactive species like hydroxyl radical, ozone, hydrogen peroxide, oxygen and
hydrogen gas and also emit UV, visible light and generate shockwaves. The main
advantage of plasma-based AOP is the generation of free hydroxyl radicals and
another reactive species without the addition of other chemicals and UV lamps [61].
This technology is widely considered for wastewater treatment due to the
following
• No requirement of external chemicals
• Environmental compatibility
• Effective process
• Simple and ease of operation at ambient temperature and pressure.
However, full-scale commercialization is hindered due to the usage of high voltage
discharge resulting in high power consumption than other treatment methods.
4.2 Ultrasound
Ultrasonic treatment also known as sonolysis or sonochemistry is a promising field in
advanced oxidation processes for removal of organic pollutant without the addition of
any chemicals. The categorization of ultrasonic treatment is based on their frequency
used.
High-frequency ultrasonic irradiation (2–10 MHz)
Low-frequency ultrasonic irradiation (20–100 kHz).
The ultrasonic reactions take place because of high irradiation of sound from
20 kHz to 1 MHz which leads to the formation of cavitation bubbles and explosions
from acoustical wave form having expansion and compression. When the size of the
R. Sukanya Devi et al.
(1) electrohydraulic discharge plasma reactors
(2) bubble discharge plasma reactors
(3) gas phase discharge plasma reactors
(4) spray discharge plasma reactors
(5) hybrid plasma reactors.
The classification is based on the total plasma–water interface, and the larger
the interface higher will be the degradation of the organic pollutants. Another
classification of plasma reactors is based on discharge
1. Corona and streamer discharge
2. Glow discharge
3. Dielectric barrier discharge (DBD)
4. Arc discharge.
Out of which, the most used is the pulsed corona discharge and pulsed arc
discharge. Non-thermal plasma can be either applied above the water surface or
applied underwater. Non-thermal plasma interacts with water to generate wide range
of reactive species like hydroxyl radical, ozone, hydrogen peroxide, oxygen and
hydrogen gas and also emit UV, visible light and generate shockwaves. The main
advantage of plasma-based AOP is the generation of free hydroxyl radicals and
another reactive species without the addition of other chemicals and UV lamps [61].
This technology is widely considered for wastewater treatment due to the
following
• No requirement of external chemicals
• Environmental compatibility
• Effective process
• Simple and ease of operation at ambient temperature and pressure.
However, full-scale commercialization is hindered due to the usage of high voltage
discharge resulting in high power consumption than other treatment methods.
4.2 Ultrasound
Ultrasonic treatment also known as sonolysis or sonochemistry is a promising field in
advanced oxidation processes for removal of organic pollutant without the addition of
any chemicals. The categorization of ultrasonic treatment is based on their frequency
used.
High-frequency ultrasonic irradiation (2–10 MHz)
Low-frequency ultrasonic irradiation (20–100 kHz).
The ultrasonic reactions take place because of high irradiation of sound from
20 kHz to 1 MHz which leads to the formation of cavitation bubbles and explosions
from acoustical wave form having expansion and compression. When the size of the