is highly efficient for removing pesticides and other organic compounds from
wastewaters due to its large surface area and porosity. Vast varieties of activated
carbons have been used including powdered activated carbon (PAC), granular
activated carbon (GAC), carbon filters, carbon cloth, and black carbon. Among
them PAC and GAC have been used widely because it is considered that they
possess great potential to remove a various pesticides effectively. Thus, today
several types of activated carbons are being produced using cheap and renewable
precursors from agricultural and industrial by-products (Ahmad et al. 2010).
A number of studies have reported the ability of lignocellulosic materials to
accumulate heavy metals and organic compounds, e.g., pesticides and dyes. The
adsorption process through these adsorbents generally occurred as a result of
interactions of pesticides with carboxyl and hydroxyl groups especially abundant
in lignin and polysaccharides, both containing almost 90% lignocellulosic materials
(Ofomaja 2008). Similarly, many industrial waste materials have been investigated
such as fly ash, carbon slurry, and sludge because they are less costly and locally
available to be used as adsorbents for removal of organic pollutants. Some of costeffective industrial and agriculture-based absorbents reported in literature are mentioned in Table 8.1.
Natural clay minerals are also considered as the strong adsorbents as they are less
costly and abundant in nature and have potential for high sorption and ion exchange.
The interest in using clay minerals as adsorbents has been increased from some
recent years for the removal of inorganic as well as organic pollutants and these clay
materials include clinoptilolite, kerolite, cloisite, montmorillonite, and faujasite.
These materials have been recognized as adsorbents due to their potential of
immobilizing organic contaminants (Sanchez-Martin et al. 2006; Suciu and Capri
2009), removing pesticides from wastewater (Cruz-Guzmán et al. 2005), and
photostablizing sorbed pesticides (Margulies et al. 1992). Adsorption process has
easily operated design, low cost, and less land requirements and is broadly used for
the removal of organic and inorganic waste materials form industrial wastewaters.
Also several low-cost adsorbents have been identified such as waste materials from
commercial, agricultural, and industrial activities, thus reducing the cost of adsorbent materials and waste management as well (Rashed 2013). However, the fouling
of adsorbents, generation of toxic sludge, and high maintenance cost are some
demerits of this process (Daǧdelen et al. 2014)
8.6.3 Membrane Technology
Membrane technology is recognized as the efficient and alternative treatment technology to conventional methods in water and wastewater treatment which has
progressed since last 25 years. Membrane technology includes variety of processes
for separation of several chemical substances through synthetic membranes to purify
water (Li et al. 2008). Membranes act as barriers and separate two phases, i.e.,
allowing certain components to pass; however other components are retained from
given mixture of feed. Electrical or chemical potential, temperature, and gradient
8 Persistent Organic Pollutants (POPs): Sources, Types, Impacts, and Their. . .
227
wastewaters due to its large surface area and porosity. Vast varieties of activated
carbons have been used including powdered activated carbon (PAC), granular
activated carbon (GAC), carbon filters, carbon cloth, and black carbon. Among
them PAC and GAC have been used widely because it is considered that they
possess great potential to remove a various pesticides effectively. Thus, today
several types of activated carbons are being produced using cheap and renewable
precursors from agricultural and industrial by-products (Ahmad et al. 2010).
A number of studies have reported the ability of lignocellulosic materials to
accumulate heavy metals and organic compounds, e.g., pesticides and dyes. The
adsorption process through these adsorbents generally occurred as a result of
interactions of pesticides with carboxyl and hydroxyl groups especially abundant
in lignin and polysaccharides, both containing almost 90% lignocellulosic materials
(Ofomaja 2008). Similarly, many industrial waste materials have been investigated
such as fly ash, carbon slurry, and sludge because they are less costly and locally
available to be used as adsorbents for removal of organic pollutants. Some of costeffective industrial and agriculture-based absorbents reported in literature are mentioned in Table 8.1.
Natural clay minerals are also considered as the strong adsorbents as they are less
costly and abundant in nature and have potential for high sorption and ion exchange.
The interest in using clay minerals as adsorbents has been increased from some
recent years for the removal of inorganic as well as organic pollutants and these clay
materials include clinoptilolite, kerolite, cloisite, montmorillonite, and faujasite.
These materials have been recognized as adsorbents due to their potential of
immobilizing organic contaminants (Sanchez-Martin et al. 2006; Suciu and Capri
2009), removing pesticides from wastewater (Cruz-Guzmán et al. 2005), and
photostablizing sorbed pesticides (Margulies et al. 1992). Adsorption process has
easily operated design, low cost, and less land requirements and is broadly used for
the removal of organic and inorganic waste materials form industrial wastewaters.
Also several low-cost adsorbents have been identified such as waste materials from
commercial, agricultural, and industrial activities, thus reducing the cost of adsorbent materials and waste management as well (Rashed 2013). However, the fouling
of adsorbents, generation of toxic sludge, and high maintenance cost are some
demerits of this process (Daǧdelen et al. 2014)
8.6.3 Membrane Technology
Membrane technology is recognized as the efficient and alternative treatment technology to conventional methods in water and wastewater treatment which has
progressed since last 25 years. Membrane technology includes variety of processes
for separation of several chemical substances through synthetic membranes to purify
water (Li et al. 2008). Membranes act as barriers and separate two phases, i.e.,
allowing certain components to pass; however other components are retained from
given mixture of feed. Electrical or chemical potential, temperature, and gradient
8 Persistent Organic Pollutants (POPs): Sources, Types, Impacts, and Their. . .
227