Emerging Water Pollutants and Wastewater Treatments
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ion exchangers used in wastewater treatment is polymeric in nature with diverse
functional groups that attracts ions from the solution. Resins are either cationic or
anionic in nature with a relatively high recovery efficiency rate. It is simple to operate;
it can be recycled and reused. Resins are non-bio-degradable, and commercial resins
are very costly; this is a major drawback for its use in ion exchange [120].
6.4 Catalytic Process
The catalytic process is one of the advanced treatment techniques employed for
wastewater treatment. It operates through the improvement of the advanced oxidation process with a catalyst. There are two different classes of catalysts employed
for wastewater treatment which include heterogeneous and homogeneous catalysts
[121]. However, the regeneration and reusability of catalysts are paramount due
to its high cost. These characteristics make heterogeneous catalysts more viable
than homogeneous catalysts due to ease of separation from reaction mixture [122].
Also, it attracts more attention due to its high removal efficiency rate, high oxidative
capacity, no intermediate pollutants and strong mineralization rate [123]. Some of
these catalytic processes include catalytic ozonation, photocatalyst, catalytic wet air
oxidation, etc.
In the catalytic ozonation process, hydroxyl radicals (OH) are formed through
an interfacial reaction mechanism that reacts with a variety of organic compounds
in wastewater. Degradation of micropollutants is enhanced with processes established on the utilization of hydroxyl radicals [124]. Ozone conversion into hydroxyl
radicals through a series of chain reactions is enhanced with the catalyst materials which in turn attracts the ozone molecules [122]. Also, larger toxic organic
compounds in wastewater are degraded with catalytic wet air oxidation technique.
Air/oxygen over a catalyst oxidized these larger compounds either completely into
carbon dioxide and water or partially into smaller weight organic compounds. These
smaller-weight organic compounds are further mineralized into carbon dioxide and
water but required more energy to achieve this [125] Catalyst materials include Febased catalyst [126], horseradish/H 2 O 2 [127], ZNPO molecular sieves [128] among
others.
The main objective of the catalytic process is to reduce the toxicity of wastewater
effluent either by conversion to biodegradable intermediate or complete conversion
to carbon dioxide and water.
6.5 Adsorption
Adsorption is an aspect of surface chemistry that involves the sequestration of
contaminants (adsorbate) by a surface or interface of the adsorbent. It finds applications in the following areas: removal and separation of substances from gas and
27
ion exchangers used in wastewater treatment is polymeric in nature with diverse
functional groups that attracts ions from the solution. Resins are either cationic or
anionic in nature with a relatively high recovery efficiency rate. It is simple to operate;
it can be recycled and reused. Resins are non-bio-degradable, and commercial resins
are very costly; this is a major drawback for its use in ion exchange [120].
6.4 Catalytic Process
The catalytic process is one of the advanced treatment techniques employed for
wastewater treatment. It operates through the improvement of the advanced oxidation process with a catalyst. There are two different classes of catalysts employed
for wastewater treatment which include heterogeneous and homogeneous catalysts
[121]. However, the regeneration and reusability of catalysts are paramount due
to its high cost. These characteristics make heterogeneous catalysts more viable
than homogeneous catalysts due to ease of separation from reaction mixture [122].
Also, it attracts more attention due to its high removal efficiency rate, high oxidative
capacity, no intermediate pollutants and strong mineralization rate [123]. Some of
these catalytic processes include catalytic ozonation, photocatalyst, catalytic wet air
oxidation, etc.
In the catalytic ozonation process, hydroxyl radicals (OH) are formed through
an interfacial reaction mechanism that reacts with a variety of organic compounds
in wastewater. Degradation of micropollutants is enhanced with processes established on the utilization of hydroxyl radicals [124]. Ozone conversion into hydroxyl
radicals through a series of chain reactions is enhanced with the catalyst materials which in turn attracts the ozone molecules [122]. Also, larger toxic organic
compounds in wastewater are degraded with catalytic wet air oxidation technique.
Air/oxygen over a catalyst oxidized these larger compounds either completely into
carbon dioxide and water or partially into smaller weight organic compounds. These
smaller-weight organic compounds are further mineralized into carbon dioxide and
water but required more energy to achieve this [125] Catalyst materials include Febased catalyst [126], horseradish/H 2 O 2 [127], ZNPO molecular sieves [128] among
others.
The main objective of the catalytic process is to reduce the toxicity of wastewater
effluent either by conversion to biodegradable intermediate or complete conversion
to carbon dioxide and water.
6.5 Adsorption
Adsorption is an aspect of surface chemistry that involves the sequestration of
contaminants (adsorbate) by a surface or interface of the adsorbent. It finds applications in the following areas: removal and separation of substances from gas and