Environmental Engineering Reference
In-Depth Information
Fig. 3.10
MSW dump site
and its cross section
of chemicals, called non-methane organic compounds (NMOCs), which may be
present in the air near a landfill, though they are not likely to reach harmful levels.
4
Phyto-Treatment of CPP Fly Ash Slurry and Landfill
Leachate
In order to meet the power demand, NALCO had its own captive power plant
(CPP). Fly ash slurry is collected in wetlands which are treated effectively and
the treated water is recirculated for use in the smelter (Kadlec and Knight
1996
;
Prasad et al.
2006
). Aquatic macrophytes e.g.
Typha latifolia
,
Eichhornia crassipes
,
Ipomea
sp.
Lemna minor
,
Polygonum
sp.,
Alternanthera philoxeroides
,
Phragmites
sp.
are the key players in the wetland (Figs.
3.11
and
3.12
)
Macrophytes possess extraordinary ability to survive the adverse conditions of
pollution and possess high colonization rate that are virtual tools of excellence for
phytoremediation. Both submerged and emergent macrophytes play an important
role in metal bioavailability from sediments through rhizosphere exchanges and
other carrier chelates. These phenomena facilitates metal uptake by other floating
and emergent forms of macrophytes (Prasad et al.
2006
). Several of the macro-
phytes bioconcentrate reduced form of the metals from sediments, making them
immobile (Okurt et al.
1999
).
Salix, Sorghum
and Water hyacinth (
Eichhornia crassipes
) contain β—cyano-
alanine synthase (CAS) which catalyzes the conversion of free cyanide and cysteine
to is β cyanoalanine. The final metabolite is asparagine, a non-toxic essential amino
acid (Korte et al.
2000
; Ebel et al.
2007
; Fig.
3.13
).
