Page 197 - Industrial Wastewater Treatment, Recycling and Reuse

Advanced Oxidation Technologies for Wastewater Treatment: An Overview 171

Generator

Ozone bubble

Ozone generator

Gas sparger
(a) Ultrasonication with ozone

– Ozone bubble
– Cavitation bubble
Cooling P
2
water out
Ozone injection at the throat of
cavitating device
P
Cooling Collection tank 1
water in for effluent V 2 V 3
V
1
Pump
P , P – Pressure gauges V 1 , V , V – Control valves
3
1 2 2
(b) Hydrodynamic cavitation with ozone
Figure 3.7 Schematic of the combined process of cavitation and ozone.

•
ensures minimal escape of unreacted O 3 due to rapid dissociation into OH
radicals and improved mass transfer, ensuring maximum utilization of ozone
for the oxidation of pollutant molecules.

3.5.3 Cavitation Coupled with Photocatalysis

In the case of photocatalytic oxidation, the most common problem is the
reduced efficiency of a photocatalyst with continuous operation, possibly
due to the adsorption of contaminants at the surface and the blocking of
the UV activated sites, which makes them unavailable for the process of
destruction. Process development for continuous cleaning of the catalyst
surface during photocatalytic operation is necessary for the successful