Environmental Engineering Reference
In-Depth Information
TABLE 17.1 (Continued)
Reported Regeneration Methods of Adsorbents
Mode of
Regeneration
Regeneration
Media
Sr. No
Adsorbents
Eficiency (%)
Reference
19
Synthetic iron(III)
-Al(III)-Cr(III) ternary
mixed oxide
Batch
0.1 M NaOH
75.00
Biswas et al., 2010
0.25 M NaOH
81.00
0.5 M NaOH
89.00
0.75 M NaOH
91.00
20
Zirconium-impregnated
cashew nut shell carbon
Batch
2.5% NaOH
96.20
Alagumuthu and
Rajan, 2010
21
Cerium-impregnated
chitosan
Batch
pH 12
93.00
Swain et al., 2010
22
Chemically modiied
bentonite clay
Batch
1 M NaOH
97.00
Kamble et al.,
2010
Maliyekkal et al. (2008) have recoated the material with manganese oxide and reacti-
vated the surface after a number of cycles of the adsorption/desorption process, without a
considerable loss in eficiency. This recoating process is important from both an economic
and disposal point of view. The recoating process reduces the amount of hazardous solid
waste generated, thereby reducing the risk associated with its disposal. From the economic
perspective, factors like cost of the new adsorbent and the cost associated with transporta-
tion and safe disposal of the exhausted material can be reduced. The life cycle assessment
of the adsorbent or any other material can provide the more realistic overall environmen-
tal impacts of material used for deluoridation of water.
17.7.8.4.1 Domestic Deluoridation Units in Sri Lanka (from Handbook of
Drinking Water Technologies by MDWS [Ministry of Drinking
Water and Sanitation] and CSIR-NEERI, 2013, IGRAC [International
Groundwater Resources Assessment Centre] Report 2007)
This deluoridation unit applies freshly ired brick pieces and is used in Sri Lanka for
the removal of luoride in a domestic deluoridation approach. The brick bed in the unit
is placed on the top with charred coconut shells and pebbles to adjust the back pressure.
Water is lown through the unit in an uplow mode. The performance of domestic units
has been evaluated in rural areas of Sri Lanka as reported by Priyant and Padmassri (1997).
The luoride removal eficiency signiicantly depended on the quality of the freshly burnt
bricks. The unit could be used for 20-40 days, with the treated water volume per day at
around 8 L and input water luoride concentration of 5 mg/L. A deluoridator made out of
cement and bricks have also been recommended for low-cost ield application.
17.7.8.4.2 ICOH (Inter-Country Centre for Oral Health) Domestic
Deluoridator (from Handbook of Drinking Water Technologies by
MDWS and CSIR-NEERI, 2013, IGRAC Report 2007)
The ICOH (at the University of Chiang Mai, Thailand) domestic deluoridator was devel-
oped in Thailand by using crushed charcoal and bone char as adsorption media. The
deluoridation eficiency of this device was reported to depend on the luoride concentra-
tion in raw water. Field trials in Thailand, Sri Lanka, and some African countries have
shown interesting results for luoride removal from water from a variety of sources.
