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CHAPTER 3

Advanced Oxidation Technologies

for Wastewater Treatment: An

Overview

1
2
2
Virendra K. Saharan , Dipak V. Pinjari , Parag R. Gogate , Aniruddha
B. Pandit 2
1
Chemical Engineering Department, Malaviya National Institute of Technology, Jaipur, India
2
Chemical Engineering Department, Institute of Chemical Technology, Mumbai, India
3.1 INTRODUCTION
In today’s industrial arena, new molecules are developed and manufactured
to meet the ever-increasing human demand; thus, a lot of new hazardous
molecules are being added continually to our water bodies through effluents
coming from different manufacturing units. The waste coming from various
chemical-producing industries, including pesticides, pharmaceutical, petro-
chemical, and other process units, contains complex molecules that are bio-
refractory in nature and thus cannot be completely degraded by conventional
biological processes. With more stringent rules and regulations, these
industries do not have any choice but to treat these chemicals up to a safe
dischargeable limit. Various methods are available to treat waste effluent;
the operation of a typical wastewater treatment unit utilizes a combination
of various physical, chemical, and biological processes.
The processes involved in the operation of a wastewater treatment unit
consist of primary treatment (e.g., screening, mixing, flocculation, sedimenta-
tion, flotation, and filtration), secondary treatment (e.g., aerobic, anaerobic,
anoxic, and facultative processes), and tertiary/advanced treatment (e.g.,
adsorption, ion exchange, membrane filtration, disinfection, and oxidation
using chemicals). Most of these processes, apart from biological treatment
and chemical oxidation, do not involve chemical transformations and there-
fore generally transfer waste components from one phaseto another, thus caus-
ing secondary loading of the environment. On the other hand, the high
fabrication and maintenance costs of advanced tertiary treatment make
these processes uneconomical. Such technoeconomic limitations make these
processes unviable; therefore, new techniques that can overcome these
techno-economic limitations need to be developed.
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