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Rhizofiltration of heavy
metals from the tannery sludge by the anchored hydrophyte,
Hydrocotyle umbellata L.
Sheza Khilji and Firdaus-e-Bareen*
Department
of Botany, University of the Punjab, Lahore -54590,
Pakistan.
*Corresponding author. E-mail:
fbareen@gmail.com,
shezakhilji@gmail.com.
Accepted
20 August, 2008 |
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The anchored hydrophyte, Hydrocotyle umbellata L., was
employed for the removal of toxic metals from tannery sludge
concentrations (w/v) from a tanneries wastewater treatment
plant. Different concentrations of wet tannery sludge were
prepared and plants of H. umbellata showed a good
tolerance for all the prepared concentrations. Plants were
retrieved after 30, 60 and 90 days and the sludge
concentrations showed reduction in sodium chloride,
chlorides and chemical oxygen demand (COD). The accumulation
of toxic metals in the plants was significantly increased,
with increasing exposure time of plants. A higher amount was
accumulated in the roots than in the shoots. The
bioconcentration factor of Cr was higher than that of Zn and
Cu at the same exposure time, indicating a higher
accumulation potential of Cr by H. umbellata. The
order of uptake efficiency was Cr > Zn > Na > Cu and the
maximum metal uptake was observed after 90 days of exposure
of H. umbellata, being 18,200 mg kg -1
for chromium, 15,560 mg kg -1 for zinc 7,692 mg
kg -1 for sodium and 6,660 mg kg -1
for copper in the roots. These plants not only tolerated up
to 60% concentration of tannery sludge but also reduced
chromium content of sludge to a considerable extent.
Key
words:
Phytoremediation, rhizofiltration, tannery sludge, heavy
metals, hydrophytes. |
