Environmental Engineering Reference
In-Depth Information
2
Engineered Phyto-Covers
Engineered phyto-covers or natural cap means the pollutants (toxic industrial
waste) are contained by vegetation integrated with engineering principles and asso-
ciated processes. Establishment of phytocovers on contaminated sites is a possible
solution to reduce the pressure on land resources. Thus, land resources on a global
perspective are under immense pressure. The pressure on available land resources
is gradually increasing because of land degradation, the growing world population,
global economic development, urbanization, industrialization and scarce resources
increase the price of available resources. Therefore, contaminated/polluted lands
must be put to use.
The Vegetative caps (phyto-cover technology) help in containment of hazard-
ous wastes because of the expense and risk associated with treating or removing
large volumes of hazardous wastes. Both regulators and the public usually accept
phyto-covers as part of remediation (Bolshakov and Chibrik
2007
; Bradshaw
2000
)
Therefore, phyto-covers enhance
in-situ
remediation. Phyto-covers protect the pub-
lic health and the environment. In this case the hazardous waste is isolated from
receptors and contained in the landfill with the help of phyto-cover. Prior to the es-
tablishment of vegetative covers, hazardous wastes are stored in warehouses which
has its own disadvantage.
2.1
a) Hazardous Waste—Aluminium Smelter Pot Lining
Material
The National Aluminium Company Limited (NALCO) is Asia's largest integrated
aluminium production complex is located at Angul in Odisha State of India. NALCO
is involved in bauxite mining, alumina refining, aluminium smelting, casting, and
production of aluminum ingots. The aluminium smelter plant and Captive Power
Plant (CPP) are situated in Angul. Odisha. The Aluminium smelter located at Angul
had 2,30,000 tons per anum (tpa) capacity and is being expanded to 3,45,000 tpa.
Aluminium Smelter at Angul also established a Captive Power Plant of 720 MW
capacity, comprising 6 × 120 MW for firm supply of power to the Smelter. Presently,
the capacity is being expanded to 960 MW. The water for the plant is drawn from
River Brahmani through a 7 km long double circuit pipeline. The coal demand is
met from a mine of 3.5 million tpa capacity opened up for NALCO at Bharatpur
in Talcher by Mahanadi Coalfields Limited. Several hundreds of tons of spent pot
line (hazardous waste containing fluoride and cyanide) are produced by the smelter
(Fig.
3.1
). The problem of piledup hazardous waste has become a serious environ-
mental problem which was tackled by different phytoremediation strategies.
Figure
3.1
Spent -pot line (Hazardous waste containing fluoride and cyanide)
packed and stored in several barracks.
Typically engineered cross section of vegetative cap (natural cap) is shown in
Figs.
3.2
and
3.3
