Page 19 - Volume 3, Issue 1, January 2010

© Benaki Phytopathological Institute
Charistou et al. 18
OMW dumping in the environment is an act
of pollution of drinking water, and a threat
to aquatic organisms and plants (1, 3, 24).
The determination of OMW toxicity to
aquatic organisms is of major importance
for characterizing its ecotoxicological prop-
erties mainly associated with the high poly-
phenol content. Recently, several methods
have been developed for the treatment of
OMW aiming at the recovery of high added
value-contained polyphenols and the po-
tential reduction of the environmental im-
pact.
In previous studies, the fungi Phanero-
chaete spp. (i.e. P. flavido-alba and P. chrys-
osporium) and Pleurotus ostreatus had been
used for biological treatment of OMW to
achieve a reduction in the polyphenol con-
tent and decolorization (2, 12, 21). The ef-
fect of fungal treatments on OMW toxicity
has been studied on the aquatic organisms
Artemia sp. and Daphnia magna (2, 12). Oth-
er approaches to the treatment of OMW in-
clude the use of microorganisms, such as
Geotrichum sp., Aspergillus sp. and Candi-
da tropicalis (7), aiming at reducing its or-
ganic potential (Chemical Oxygen Demand,
COD), the use of centrifugation–ultrafiltra-
tion techniques in order to remove the solid
and organic content (22), the use of sodium
polyacrylate polymers (6) or the application
of electrophysical methods for the reduc-
tion of the toxicity potential of OMW (9).
More recently, a pilot scale system for
the treatment of OMW has been developed
in the frames of the EU LIFE-Environment
programme MINOS (1) aiming at the isola-
tion of high added value-contained poly-
phenols and the minimization of environ-
mental problems.
In the present study, the acute toxicity of
OMW, produced in a three-phase olive mill
in Rouva municipality in the island of Crete,
Greece, was determined on Wistar rats and
two marine species, the photobacterium Vi-
brio fischeri (Microtox® assay) and the crus-
tacean Artemia fransiscana. These marine or-
ganisms have beenwidely used as indicators
for the toxicity evaluation of environmen-
tal pollutants or other chemical substanc-
es (17, 18, 19, 23). Therefore, in the present
study the above mentioned organisms have
been used taking into account that the olive
mill wastes are a source of pollution for the
marine environment. The acute toxicity on
the aquatic organisms was also determined
for both the treated OMW [as described by
Agalias et al., 2007 (1)] and the isolated poly-
phenol mixtures in comparison with the tox-
icity of the untreated OMW.
Materials and methods
Treatment of OMW
Olive mill wastewater produced in a
three-phase olive mill was treated using
a recently developed method (1). In brief,
fresh OMW (pH=5.15-5.23) was filtrated
through two different filters for gradual re-
moval of the wastewater suspended solids
of 50 μm in size. Then, filtrate was succes-
sively passed through a series of columns
packed with XAD-4 and XAD-7HP adsorbent
resins (1st cycle extract, pH=5.18). The sec-
ond step was repeated twice (2 nd cycle ex-
tract, pH=4.80) for the achievement of maxi-
mal deodorization and decolorization of the
wastewater and sufficient removal of the
polyphenols.
The samples used in the toxicity assays
were the following: untreated OMW, treat-
ed OMW after one cycle of treatment, treat-
ed OMW after two cycles of treatment, poly-
phenolic mixture recovered from OMW
passed through column XAD-4 and poly-
phenolic mixture produced by OMW passed
through column XAD-7HP. The recovered
polyphenolic fractions from columns XAD-
4 and XAD-7HP were 5.8 and 3 g/l of treated
OMW, respectively.
Bioassays for the determination of OMW
toxicity
The toxicity tests were performed on
Wistar rats and two aquatic organisms, the
bioluminescent bacterium V. fischeri (NRRL
B-11177) and the crustacean A. fransiscana.
The Wistar rats were obtained from the
breeding colony of the Benaki Phytopatho-