2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology
into specific environmental conditions and during period of
about 3 days testing organisms are ready for use. Daphnids
aged less than 24 were exposed to the sewage leaching at
a range of concentrations 50, 100, 200, 500, 700 ml dm –3 in
definitive tests for a period of 24 and 48 hours at 20–22 °C
and light intensity of 6,000 lux. Immobilization was recorded
at 24 hours and 48 hours and compared with control values.
The results were analyzed in order to calculate the EC50 at 24
and 48 h. Determination of the EC50 at 24 h is optional.
The Thamnotoxkit FTM uses the testing organism Thamnocephalus
platyurus, aged less than 24 hours. The exposition
was 24 h at a range of the same concentrations at 20–22 °C
and 4,000 lux. The obtained results were analysed and the
values LC50 at 24 h were calculated. Two above mentioned
tests are alternative tests, whilst the test on Sinapis alba represents
standard phytotoxicity test. This root growth inhibition
toxicity test was used as a standard OECD test. The high quality
seeds of Sinapis alba were exposed for 78 hours to tested
solution, at temperature 20 ± 2 °C in the dark. After 78 hours
the lengths of hypocotyls of seeds in tested and in control
group were measured and values of IC50 were evaluated.
For a validation of test it is necessary to apply the following
performance criteria; Daphnotoxkit FTM and Thamnotoxkit
FTM – number of dead and immobile organisms should not
exceeded 10 % in control. In root growth inhibition toxicity
test germinability should be more than 90 %.
Results
On the base of the analysis of obtained ecotoxicological
data the values of EC50, LC50 and IC50 were evaluated
for various samples of sewage sludges. These values made
possible the evaluation of sludges ecotoxicity and also facilitated
their categorization from the point of view of the leacha-
Table I
The ecotoxicity of sewage sludges and their classification
24h-EC50 or
Sewages
sludges 24h-LC50
[ml dm –3 ]
Class of
leachability
AS 22.81 III
DWAS 39.57 II
DSAS 139.64 III
PS 38.17 III
s530
Fig. 1. Comparison of ecotoxicity of tested sewage sludges using
testing organisms Thamnocephalus platyurus
bility. Table I summarizes values of 24h-EC50 or 24h-LC50
for the most sensitive testing organisms, which form the basis
for evaluation and categorization of sewage sludges.
Conclusions
Different sewage sludges were tested in respect to their
possible hazardous characteristic - ecotoxicity. On the bases
of obtained results sewage sludges were classified in term
of their leachability. no sample of sewage sludge exhibit
ecotoxicity following the Czech legislation.
This work has been supported by grant COST, action
636, project No. OC-183.
REFEREnCES
1. Wilke, B. M., Riepert, F., Christiane Koch., Kühne, T.:
Ecotoxicol. Environ. Saf., 70, 283 (2008).
2. Kubík, V., Hofman, J., Holoubek, I.: Abstract Book
of SETAC Europe the 16th Annual Meeting. Hague,
netherlands: SETAC, 2006. p. 79. 7.5.2006, Hague, The
netherlands., Issue 2, June 2008, pp 283
3. OECD Environmnetal health and Safety Publications:
OECD Guidelines for Testing Chemicals no. 202
(2004).
4. OECD Environmnetal health and Safety Publications:
OECD Guidelines for Testing Chemicals no. 208
(2006).