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Jūratė Žaltauskaitė, Gintarė Sujetovienė, Agnė Čypaitė, Agnė Aužbikavičiūtė
Lemna minor as a tool for wastewater toxicity assessment and pollutants
removal agent
| Conference Information: |
9th International Conference on Environmental
Engineering, MAY 22-24, 2014 Vilnius, LITHUANIA |
| Source: |
ICEE-2014 - International Conference on Environmental
Engineering |
| Book Series: |
International Conference on Environmental Engineering
(ICEE) Selected papers |
| ISSN: |
ISSN 2029-7092 online |
| ISBN: |
978-609-457-640-9 / 978-609-457-690-4 CD |
| Year: |
2014 |
| Publisher: |
Vilnius Gediminas Technical University Press Technika |
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Abstract
Municipal effluents are of major concern for the quality of the receiving water bodies. In this study the toxicity of municipal effluents was
evaluated using the bioassays with aquatic higher plant common duckweed (Lemna minor L.). The aim of the study was to evaluate the
applicability of L. minor for wastewater toxicity testing and it’s efficiency in toxicants removal. Toxicity tests were performed on samples
of untreated and biologically treated wastewater of small city Šilalė. Chemical analysis recorded high concentrations of nutrients and
heavy metals in untreated wastewater. Wastewater treatment significantly reduced (up to 60%) the content of nutrients (N, P), however
only slight reduction (up to 10%) in the concentrations of heavy metals was observed. Both, untreated and biologically treated wastewater
inhibited the relative growth rate of L. minor, affected the biomass of L. minor fronds, the content of photosynthetic pigments (chlorophyll
a, b) and induced oxidative stress. Undiluted wastewater was extremely phytotoxic and led to the death of test organisms. However due to
high concentrations of nutrients (N, P) treated wastewater may even stimulate the growth of L. minor and may mask the toxicity of other
toxicants (such as heavy metals). It was observed that Lemna minor can be used as wastewater phytoremediation agent, as they have the
capacity to remove relative high amounts of PO4
3-
and NH4
+ from the wastewater, they may significantly reduce the concentrations of
NO3
-
in wastewater and slightly reduce the content of SO4
2-
. L. minor removed the heavy metals from the wastewater and it was detected
that the concentrations of Zn, Mn, Cu and Cd in wastewater were reduced after the growth of L. minor, however, the removal of Pb was
negligible.
Keywords:bioassays; Lemna minor; toxicants removal; toxicity testing; wastewater.
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