removal of suspended solids and leaves less turbidity. Removal capacity of turbidity
from the wastewater by alum, ferrous sulfate, ferric chloride, and calcium oxides was
found to be 99.59%, 98.26%, 98.66%, and 92.18%, respectively (Farhan 2019).
6.5.1.3 Ion Exchange
Ion exchange process is a physical approach for removing heavy metals from the
wastewater. In this process, ions are reversibly interchanged between the solid, i.e.,
natural or synthetic solid resin and liquid phase. Resins uptake ions from electrolytic
solution and release ions which are similar in charge or chemically equivalent
(Cavaco et al. 2007).
6.5.1.4 Through Adsorption Process
Adsorption process is a widely accepted physicochemical technique. It is based on
the exchange of mass between liquid phase, i.e., wastewater and solid phase, i.e.,
adsorbent. Adsorption process is completed in several steps, first of all, contaminants
move from wastewater to the surface of adsorbent, in the second step contaminants
lock or adsorbed on adsorbent surface, and in the final step penetration of contaminants to the adsorbent structure. Adsorption process has been done in both, natural
byproducts, e.g., rubber, cotton, rice husk, jute fiber, etc., and synthetic byproducts,
e.g., zeolite, activated carbon, fly ash, iron slag, etc. (Salam et al. 2011). Huang et al.
(2018) reported the removal of heavy metal (Pb, Cu, etc.) from wastewater through
two types of zeolite, i.e., ZIF-8 and ZIF-67. ZIF-8 synthesized by addition of
2-methylimidazole and zinc nitrate hexahydrate (Zn (NO 3 ) 2 Á6H 2 O) in solvent
of N, N-dimethylformamide (DMF). ZIF-67 synthesized by addition of
2-methylimidazole and cobalt nitrate hexahydrate (Co(NO 3 ) 2 Á6H 2 O) in a DMF
solvent. Zeolite is highly porous material, which helps in improving the adsorption
capacity. Adsorption capacity of ZIF-8 and ZIF-67 was 1119.80 and 1348.42 mg/g
for Pb, and 454.72 and 617.51 mg/g for Cu, respectively. Adsorption capacity of
such types of zeolite was very higher, take few minutes to reach adsorption equilibrium. These characteristics proved that ZIF-8 and ZIF-67 have good adsorption
capacity for the removal of heavy metals from wastewater (Huang et al. 2018). De
Abreu Domingos and da Fonseca (2018) performed a comparative study for the
treatment of petroleum refinery wastewater by an adsorption process using activated
carbon and ion exchange process through resins (styrene–divinylbenzene). The
study verified the feasibility and reliability of both the processes and showed that
the removal of contaminants from petroleum refinery wastewater through adsorption
by activated carbon was 55% higher than the ion exchange process.
6 Wastewater Reuse in Peri-Urban Agriculture Ecosystem: Current Scenario,. . .
133
from the wastewater by alum, ferrous sulfate, ferric chloride, and calcium oxides was
found to be 99.59%, 98.26%, 98.66%, and 92.18%, respectively (Farhan 2019).
6.5.1.3 Ion Exchange
Ion exchange process is a physical approach for removing heavy metals from the
wastewater. In this process, ions are reversibly interchanged between the solid, i.e.,
natural or synthetic solid resin and liquid phase. Resins uptake ions from electrolytic
solution and release ions which are similar in charge or chemically equivalent
(Cavaco et al. 2007).
6.5.1.4 Through Adsorption Process
Adsorption process is a widely accepted physicochemical technique. It is based on
the exchange of mass between liquid phase, i.e., wastewater and solid phase, i.e.,
adsorbent. Adsorption process is completed in several steps, first of all, contaminants
move from wastewater to the surface of adsorbent, in the second step contaminants
lock or adsorbed on adsorbent surface, and in the final step penetration of contaminants to the adsorbent structure. Adsorption process has been done in both, natural
byproducts, e.g., rubber, cotton, rice husk, jute fiber, etc., and synthetic byproducts,
e.g., zeolite, activated carbon, fly ash, iron slag, etc. (Salam et al. 2011). Huang et al.
(2018) reported the removal of heavy metal (Pb, Cu, etc.) from wastewater through
two types of zeolite, i.e., ZIF-8 and ZIF-67. ZIF-8 synthesized by addition of
2-methylimidazole and zinc nitrate hexahydrate (Zn (NO 3 ) 2 Á6H 2 O) in solvent
of N, N-dimethylformamide (DMF). ZIF-67 synthesized by addition of
2-methylimidazole and cobalt nitrate hexahydrate (Co(NO 3 ) 2 Á6H 2 O) in a DMF
solvent. Zeolite is highly porous material, which helps in improving the adsorption
capacity. Adsorption capacity of ZIF-8 and ZIF-67 was 1119.80 and 1348.42 mg/g
for Pb, and 454.72 and 617.51 mg/g for Cu, respectively. Adsorption capacity of
such types of zeolite was very higher, take few minutes to reach adsorption equilibrium. These characteristics proved that ZIF-8 and ZIF-67 have good adsorption
capacity for the removal of heavy metals from wastewater (Huang et al. 2018). De
Abreu Domingos and da Fonseca (2018) performed a comparative study for the
treatment of petroleum refinery wastewater by an adsorption process using activated
carbon and ion exchange process through resins (styrene–divinylbenzene). The
study verified the feasibility and reliability of both the processes and showed that
the removal of contaminants from petroleum refinery wastewater through adsorption
by activated carbon was 55% higher than the ion exchange process.
6 Wastewater Reuse in Peri-Urban Agriculture Ecosystem: Current Scenario,. . .
133