mixing of alum (as a flocculant) and potassium permanganate (as an oxidizing
agent). This mixture is allowed to settle after stirring for a couple of minutes.
Then, the settled water is passed to lower bucket through the pipe attached to the
lower end of upper bucket (Tahura et al. 1998; Souter et al. 2003). The arsenic-free
water is collected from the lower part of the bucket after passing through sand filter.
The obtained aluminium-arsenic complex can be removed by filtration process at the
end of remediation process.
Sono-filter is an another simpler household technique, which involves the process
of oxidation, precipitation, adsorption and filtration during removal of arsenic
(Leupin et al. 2005; Hussam 2009). It consists of the top and middle pots as reactors
along with the lower one as storage pot for treated water. The layers of polyester
cloth, coarse sand, iron chips and polyester cloth, fine sand and charcoal are placed
as removal material medium in top and middle pot of the filter system, respectively.
This approach has been reported to be quite efficient for arsenic removal in the pH
range of groundwater, which involves surface complexation reaction mechanisms.
Arsenic bio-sand filter (ABF) is among the one of the most effective and
economical technologies adopted for arsenic removal to provide drinking water in
rural areas (Shah et al. 2015). It consists of two layers, such as pathogen removal unit
(PRU) and ATU (ARU), representing the lower part and upper part of the filter
system, respectively. These parts are equipped with iron nails, polyester cloth, metal
diffuser box and fine sand, coarse sand and gravels as components of ARU and PRU,
respectively.
This filter works on the principal of arsenic removal through adsorption onto iron
hydroxides and slow sand filtration mechanism (Ahammed and Davra 2011). The
formation of iron hydroxide particles responsible for arsenic adsorption is produced
after the oxidation of iron nails in the presence of air. Then, arsenic-loaded water is
allowed to pass through underlined sand filter to acquire potable water. Further, the
PRU unit is considered to remove the pathogens by steps, such as mechanical
trapping (occurs due to entrapment of pathogens along with sediments in the space
between the consolidated materials), adsorption (attachment of pathogens to
sediments and each other), predation (consumption due to already existing microbes
in biofilm layer) and natural death due to scarcity of food.
2.5.2 Community-Based Treatment Systems
In rural areas, many people consume water from common tube wells and
handpumps. To provide safe drinking water, arsenic treatment unit (ATU) is generally attached to water source, which is operated with an intermittent flow of water.
Generally, the conventional treatment is done through the processes, such as mixing
of chemicals, flocculation, sedimentation and filtration (Duarte et al. 2009; Chen
et al. 1999). In the first stage, sodium hypochlorite and alum are added to the arsenic
infested water for the oxidation and coagulation, respectively. In the second stage,
the mixing of these chemicals leads to the formation of flocks containing arsenic,
which is followed by sedimentation and filtration to get arsenic-free water. Recently,
42
A. Kumar et al.
agent). This mixture is allowed to settle after stirring for a couple of minutes.
Then, the settled water is passed to lower bucket through the pipe attached to the
lower end of upper bucket (Tahura et al. 1998; Souter et al. 2003). The arsenic-free
water is collected from the lower part of the bucket after passing through sand filter.
The obtained aluminium-arsenic complex can be removed by filtration process at the
end of remediation process.
Sono-filter is an another simpler household technique, which involves the process
of oxidation, precipitation, adsorption and filtration during removal of arsenic
(Leupin et al. 2005; Hussam 2009). It consists of the top and middle pots as reactors
along with the lower one as storage pot for treated water. The layers of polyester
cloth, coarse sand, iron chips and polyester cloth, fine sand and charcoal are placed
as removal material medium in top and middle pot of the filter system, respectively.
This approach has been reported to be quite efficient for arsenic removal in the pH
range of groundwater, which involves surface complexation reaction mechanisms.
Arsenic bio-sand filter (ABF) is among the one of the most effective and
economical technologies adopted for arsenic removal to provide drinking water in
rural areas (Shah et al. 2015). It consists of two layers, such as pathogen removal unit
(PRU) and ATU (ARU), representing the lower part and upper part of the filter
system, respectively. These parts are equipped with iron nails, polyester cloth, metal
diffuser box and fine sand, coarse sand and gravels as components of ARU and PRU,
respectively.
This filter works on the principal of arsenic removal through adsorption onto iron
hydroxides and slow sand filtration mechanism (Ahammed and Davra 2011). The
formation of iron hydroxide particles responsible for arsenic adsorption is produced
after the oxidation of iron nails in the presence of air. Then, arsenic-loaded water is
allowed to pass through underlined sand filter to acquire potable water. Further, the
PRU unit is considered to remove the pathogens by steps, such as mechanical
trapping (occurs due to entrapment of pathogens along with sediments in the space
between the consolidated materials), adsorption (attachment of pathogens to
sediments and each other), predation (consumption due to already existing microbes
in biofilm layer) and natural death due to scarcity of food.
2.5.2 Community-Based Treatment Systems
In rural areas, many people consume water from common tube wells and
handpumps. To provide safe drinking water, arsenic treatment unit (ATU) is generally attached to water source, which is operated with an intermittent flow of water.
Generally, the conventional treatment is done through the processes, such as mixing
of chemicals, flocculation, sedimentation and filtration (Duarte et al. 2009; Chen
et al. 1999). In the first stage, sodium hypochlorite and alum are added to the arsenic
infested water for the oxidation and coagulation, respectively. In the second stage,
the mixing of these chemicals leads to the formation of flocks containing arsenic,
which is followed by sedimentation and filtration to get arsenic-free water. Recently,
42
A. Kumar et al.