Combination of Fenton oxidation and composting for the treatment of the olive solid residue and the olive mile wastewater from the olive oil industry in Cyprus


Zorpas, A.A.; Costa, C.N.

Bioresource Technology 101(20): 7984-7987

2013


Co-composting of olive oil solid residue (OOSR) and treated wastewaters (with Fenton) from the olive oil production process has been studied as an alternative method for the treatment of wastewater containing high organic and toxic pollutants in small olive oil industry in Cyprus. The experimental results indicated that the olive mill wastewater (OMW) is detoxified at the end of Fenton Process and the COD is reduced up to 70%. The final co-composted material of OOSR with the treated olive mile wastewater (TOMW) is presented with optimum characteristics and is suitable for agricultural purpose. The final product coming out from an in-Vessel reactor seems to mature faster than the product from the windrow system and is presented with a better soil conditioner.

Bioresource
Technology
101
(2010)
7984-7987
Contents
lists
available
at
ScienceDirect
510F2501.1Kf
it
.
CHHOlOGY
..„
........
,
Bioresource
Technology
ELSEVIER
journal
homepage:
www.elsevier.com/locate/biortech
Short
Communication
Combination
of
Fenton
oxidation
and
composting
for
the
treatment
of
the
olive
solid
residue
and
the
olive
mile
wastewater
from
the
olive
oil
industry
in
Cyprus
Antonis
A.
Zorpas
a.*,
Costa
N.
Costa
b
'Institute
of
Environmental
Technology
and
Sustainable
Development,
Department
of
Research
and
Development,
Laboratory
of
Environmental
Friendly
Technology,
P.O.
Box
34073,
5309,
Paralimni,
Cyprus
b
Cyprus
University
of
Technology,
Department
of
Environmental
Management,
Cyprus
ARTICLE
INFO
ABSTRACT
Article
history:
Received
3
February
2010
Received
in
revised
form
6
May
2010
Accepted
10
May
2010
Keywords:
Fenton
Compost
Olive
mill
wastewater
Olive
oil
solid
residue
Co-composting
of
olive
oil
solid
residue
(OOSR)
and
treated
wastewaters
(with
Fenton)
from
the
olive
oil
production
process
has
been
studied
as
an
alternative
method
for
the
treatment
of
wastewater
contain-
ing
high
organic
and
toxic
pollutants
in
small
olive
oil
industry
in
Cyprus.
The
experimental
results
indi-
cated
that
the
olive
mill
wastewater
(OMW)
is
detoxified
at
the
end
of
Fenton
Process
and
the
COD
is
reduced
up
to
70%.
The
final
co-composted
material
of
OOSR
with
the
treated
olive
mile
wastewater
(TOMW)
is
presented
with
optimum
characteristics
and
is
suitable
for
agricultural
purpose.
The
final
product
coming
out
from
an
in-Vessel
reactor
seems
to
mature
faster
than
the
product
from
the
windrow
system
and
is
presented
with
a
better
soil
conditioner.
©
2010
Elsevier
Ltd.
All
rights
reserved.
I.
Introduction
Olive
oil
production
is
considered
one
of
the
oldest
agricultural
industries
in
the
Mediterranean
countries.
Approximately
1.8
x
10
6
t
of
olive
oil
is
produced
annually
worldwide
where
the
majority
of
it
is
produced
in
the
Mediterranean
basin.
The
aver-
age
amount
of
olive
mill
wastewater
(OMW)
produced
during
the
milling
process
is
1.2-1.8
m
3
t
-1
of
olives.
OMW
resulting
from
the
production
processes
in
the
Mediterranean
region
sur-
passes
30
million
per
year
(El-Gohary
et
al.,
2009).
The
treatment
of
liquid
wastes
produced
from
olive
oil
production
is
still
a
ma-
jor
challenge
facing
this
industry.
The
main
problem
is
attributed
to
its
dark
color,
high
organic
content
and
toxicity
which
are
due
to
the
presence
of
phenolic
compounds.
COD
values
of
OMW
may
reach
150
g
L
-1
,
most
of
which
are
in
a
particulate
form
while
suspended
solids
up
to
190
g
L
-1
have
been
recorded
(Canizares
et
al.,
2007).
Olive
oil
extraction
is
among
the
most
traditional
agricultural
industries
in
Cyprus
and
it
has
always
been,
and
is
among
the
importance
for
the
national
economy.
The
total
area
under
olive
cultivation
is
about
7400-8000
ha
with
about
2.2-
2.7
million
productive
trees.
It
is
estimated
that
olive
trees
hold
44.7%
of
the
total
agricultural
area
under
permanent
crops.
This
represents
approximately
5.6%
of
the
country's
cropped
area
*
Corresponding
author.
E-mail
addresses:
antoniszorpas@yahoo.com
,
envitech@cytanet.com.cy
,
antonis-
zorpas@envitech.org
(AA.
Zorpas),
costas.costa@cut.ac.cy
(C.N.
Costa).
URLs:
http://www.envitech.org
(AA.
Zorpas),
http://www.cut.ac.cy
(C.N.
Costa).
0960-8524/S
-
see
front
matter
©
2010
Elsevier
Ltd.
All
rights
reserved.
doi:10.1016/Lbiortech.2010.05.030
and
contributed
2.7-2.9%
of
total
agricultural
output.
Olive
mill
wastewaters
(OMW)
constitute
a
serious
environmental
problem
in
the
Mediterranean
Sea
region
due
to
the
unique
features
asso-
ciated
with
this
type
of
agro-waste,
namely
seasonal
and
local-
ized
production
(typically
between
October
and
March),
low
flowrates
(between
10
and
100
m
3
d
-1
)
and
high
and
diverse
or-
ganic
load
(Gotsi
et
al.,
2005).
The
quantity
of
olive
oil
mill
veg-
etation
and
washing
effluents
(commonly
referred
to
as
olive
mill
effluents
or
wastewaters
(OME
or
OMW)
generated,
and
con-
sequently
the
environmental
impact,
depends
on
the
method
of
olive
oil
extraction
used
(Mantzavinos
and
Kalogerakis,
2004).
In
Cyprus
today
are
based
28
small
olive
mills
(26
are
a
3-Phases
Process
and
2
are
a
2-Phases
Process)
which
have
the
ability
to
treat
all
the
production
of
olives
and
to
produce
olive
oil.
The
an-
nual
average
olive
production
is
about
13,500-15,500
t,
equiva-
lent
to
2700-3100
t
y
-1
of
olive
oil
and
resulting
in
the
generation
of
about:
18,225-20,925
t
y
-1
of
olive
mill
wastewater
(OMW
and
is
equal
with
the
water
consumption)
which
causes
serious
environmental
problems,
mainly
due
to
its
high
organic
content,
9180-10,450
t
y
-1
of
olive
oil
solid
residue
(OOSR)
and
1620-1860
t
y
-1
leaves.
Lagooning
as
physical
evaporation
and
irrigation
for
the
OMW
and
typical
composting
for
the
OOSR
are
the
main
typical
and
classic
systems
for
the
treatment
of
those
waste
until
now
in
Cyprus.
This
study
deals
with
a
physico-
chemical
approach
for
the
treatment
of
OMW
and
OOSR
with
combination
to
Fenton's
Reagents,
Composting
system
as
a
sus-
tainable
and
cost
effective
method
for
small
industries
in
Cyprus
and
other
Islands
under
warm
climate
conditions.
AA.
Zorpas,
C.N.
Costa/
Bioresource
Technology
101
(2010)
7984-7987
7985
2.
Methods
2.1.
Methods
of
analysis
The
OMW
and
the
00SR
have
been
collected
from
3
several
ol-
ive
mills
based
in
3
different
Districts
of
Cyprus.
The
District
of
Famagusta
(DF)
which
is
in
the
Eastern
Part
of
the
Island,
the
Dis-
trict
of
Larnaca
(DL)
which
is
about
40
km
away
from
the
olive
mills
of
DF
on
the
South
and
the
District
of
Paphos
(DP)
which
is
about
300
km
away
from
the
olive mills
of
DF
and
250
km
from
the
olive
mill
of
DL
on
the
west.
The
sampling
durations
were
for
about
4
months
from
October-January
and
every
second
week
50
kg
of
OOSR
and
50
L
of
OMW
were
taken
and
the
samples
were
stored
in
the
fridge
at
4
°C.
The
two
olive
mills
in
Famagusta
and
Larnaca
are
3-Phase
process
while
the
other
one
in
Paphos
is
2-
Phase
process.
For
all
the
presented
parameters
in
Table
1
and
2
a
number
of
methods
has
been
used
as
presented:
in
Standard
Methods
of
Analysis
(1995),
by
Zorpas
et
al.,
1998),
by
Zorpas
(2008),
by
Gotsi
et
al.
(2005),
by
Atanassova
et
al.
(2005),
by
Gaudy
(1962).
3.
Experimental
procedure
The
OMW
from
each
District
(DF,
DL,
DP)
was
subjected
to
Fenton
oxidation
treatment.
The
oxidation
was
carried
out
batch
wise
at
25
°C
in
an
agitated
(200
rpm),
temperature
and
pH
controlled
glass
reactor
of
1L
capacity
for
4
h.
First,
the
waste-
water
sample
was
diluted,
if
necessary.
Next,
H
2
50
4
(98%)
and
Fenton
reagent
were
added.
As
ferrous
salt,
FeSO
4
.7H
2
0
was
used
and
the
hydrogen
peroxide
was
of
30%
concentration.
After
oxidation,
vigorous
stirring,
neutralization
with
lime,
coagula-
tion
with
a
weak
anionic
polyelectrolyte
(2540
Praestol,
0.1%)
and
flocculation
in
a
jar
test
apparatus,
the
sample
was
filtered
and
the
supernatant
liquid
was
analyzed
in
terms
of
COD.
Then
the
treated
olive
mill
wastewater
(TOMW)
from
District
of
Fam-
agusta
were
mixed
with
the
OOSR
from
the
same
District
and
proceed
for
composting
in
two
several
compost
systems
accord-
ing
to
the
following
scheme:
CS1A
(00SRF
+
OMWF),
CS1B
(00SRF
+
TOMWF),
CS2A1
(00SRF
+
OMWF),
CS2B1
(OOSRF
+
TOMWF).
Table
1
Composition
of
the
olive
mill
wastewater.
3.1.
Factorial
design
The
aim
of
the
experimental
procedure
was
to
determine
the
influence
of
some
basic
process
parameters
on
the
effectiveness
of
the
oxidation
treatment
in
terms
of
%COD
removal
from
the
OMW.
These
parameters
are
dilution
of
wastewater,
heptahydrat-
ed
ferrous
sulphate
concentration,
hydrogen
peroxide
concentra-
tion,
and
sulphuric
acid
concentration.
These
parameters
are
referred
to
as
"controlling
parameters"
of
the
system.
The
effect
of
the
controlling
parameters
on
the
optimization
parameter
was
estimated
by
performing
a
24
factorial
experiment.
In
general,
by
using
a
2
n
factorial
design,
n
controlling
parameters
interrelate
to
an
optimization
parameter
through
an
appropriate
linear
model.
Their
significance
can
also
be
estimated
and
assessed
(Alder
et
al.,
1995).
Then
the
most
significant
variables
are
altered
step-
wise,
aiming
at
the
determination
of
the
optimal
experimental
conditions.
The
levels
of
the
controlling
parameters
are
includes:
Wastewater
dilution,
FeSO
4
.7H
2
0,
H202
(30%)
and
H
2
50
4
(98%)
addition.
The
variation
intervals
include
3
Levels
(+1,
0,
-1).
+1
Le-
vel
involved
zero%
wastewater
dilution,
4
g
L
-1
FeSO
4
.7H
2
0,
2
mL
L
-1
H
2
0
2
(30%)
and
0.5
mL
L
-1
H
2
50
4
(98%).
Zero
Level
involved
zero
50%
wastewater
dilution,
5
g
L
-1
FeSO
4
.7H
2
0,
2.5
mL
L
-1
H
2
0
2
(30%)
and
0.25
mL
L
-1
H
2
50
4
(98%).
-1
Level
involved
zero
100%
wastewater
dilution,
6
g
L
-1
FeSO
4
.7H
2
0,
3.5
mL
L
-1
H202
(30%)
and
0.75
mL
L
-1
H
2
50
4
(98%).
The
experimental
area
of
the
factorial
design
was
predetermined
in
previous
preliminary
trials.
In
the
24
factorial
designs,
16
experiments
were
carried
out.
Four
extra
experiments
in
the
center
of
the
design
(level
0)
were
also
conducted
for
statistical
purposes.
Each
experiment
was
repeated
three
times
and
the
results
presented
are
the
mean
values.
From
this
data,
a
mathematical
model
was
constructed.
Its
adequacy
was
checked
by
the
Fisher
criterion.
According
to
the
latter,
the
fol-
lowing
ratio
should
follow
the
F-distribution
with
level
of
impor-
tance
p
=
5%:
S
2
F
=
cd
(1)
2
-
ki)
2
S
ad
-
1
=
1
(2)
Characteristics
OMW-DF
OMW-DL
OMW-DP
Total
solids
(TS),
%
633
±
1.81
6.09
±
1.05
6.59
±
0.98
Total
volatile
solids,
%
of
TS
9036
±331
91.93
±
4.15
88.12
±
3.69
Total
organic
carbon
content,
%
of
TS
62.71
±
6.27
60.17
±
5.99
6430
±
7.12
Total
Kjeldahl
nitrogen,
%
of
TS
1.28
±
0.17
131
±
0.20
1.25
±
0.19
Total
phosphorous
as
P20
5
,
%
of
TS
0.84
±
0.17
0.92
±
0.11
0.88
±
0.11
Total
Phenolic
compounds
(g
L
-1
)
8.71
±
0.51
9.02
±
039
490
±
0.28
pH
5.66
±
03
5.52
±
0.4
5.58
±
03
EC
(mS
cm
-1
)
2120
±
57
1984
±
33
1277
±
12
Salinity
(mg
L
-1
)
CaCO3
1058
±
91
901
±28
645
±
48
BOD
5
(g
L
-1
)
173
±
5.5
20.1
±
9.7
13.7
±3.4
COD
(g
L
-1
)
70.1
±
123
57.4
±
63
45.9
±
4.5
COD/BOD
5
ratio
4.05
±
0.91
3.01
±
0.87
2.98
±
0.92
Ash,
%
of
TS
9.71
±
3.21
8.99
±
2.18
9.25
±
3.05
C/N
ratio
52.25
±
5.24
45.93
±
4.15
51.44
±
6.02
C/P
ratio
74.65
±
3.81
65.40
±
6.17
73.68
±
4.15
Specific
weight
(gr
cm
-3
)
1.048
±
0.033
1.057
±
0.029
1.022
±
0.041
Fats
&
oils
mg
(L
1
)
1.46
±
0.20
1.45
±
0.22
6307.5
±
279
Germination
index
(%)
18
±
5
16
±
7
11
±
6
Humics
(%)
0.94
±
0.12
1.04
±
0.27
0.89
±
0.21
E4/E6
134
±
0.03
1.53
±
0.05
1.44
±
0.03
K
mg
L
-1
3.1
±
0.45
2.87
±
0.50
2.17
±
0.21
Ca
mg
L
-1
271.4
±
14.1
248.7
±
16.9
210.6
±
12.2
Mg
mg
L
-1
32.8
±
53
28.2
±
4.7
22.9
±
6.1
Na
mg
L
-1
3443
±
15.1
322.6
±
16.9
209.1
±
17.2
Cl2
mg
L
-1
401.4
±
51.4
367.8
±
41.9
2123
±
24.7
7986
Table
2
Composition
of
the
olive
oil
solid
residue.
AA.
Zorpas,
C.N.
Costa/
Bioresource
Technology
101
(2010)
7984-7987
Characteristics
OOSR-DF
00SR-DL
00SR-DP
Moisture
48.71
±
2.01
50.12
±
1.92
62.1
±
2.12
Total
solids
(TS)
(%)
86.00
±
333
8534
±
4.01
77.98
±
6.71
Total
carbon
content,
%
of
TS
51.45
±
4.48
46.79
±
332
47.12
±
3.61
Total
Kjeldahl
nitrogen,
%
of
TS
1.06
±
0.15
1.12
±
0.07
0.79
±
0.10
Total
phosphorous
as
P
2
0
5
,
%
of
TS
0.11
±
0.01
0.13
±
0.01
0.07
±
0.01
Fats
and
oils,
%
of
TS
4.65
±
1.09
4.89
±
1.21
6.02
±
0.93
Proteins,
%
of
TS
3.29
±
0.12
3.97
±
0.19
2.43
±
0.19
Total
sugars,
%
of
TS
1.07
±
0.09
1.12
±
0.11
0.96
±
0.04
Cellulose,
%
of
TS
22.27
±
0.44
1931
±
0.96
1630
±
0.47
Hemicellulose,
%
of
TS
16.57
±
0.94
14.90
±
0.78
9.45
±
1.02
Ash,
%
of
TS
3.65
±
0.25
4.01
±
0.44
3.12
±
0.17
Other
extraction
substances,
%
of
TS
838
±
035
9.45
±
0.59
7.12
±
0.28
Lignin,
%
of
TS
11.95
±
0.45
14.41
±
0.87
939
±
0.68
Potassium
as
K20,
%
of
TS
0.83
±
0.11
0.91
±
0.07
0.87
±
0.11
Calcium
content,
%
of
TS
0.72
±
0.08
0.67
±
0.03
0.65
±
0.04
C/N
ratio
48.53
±
5.03
41.77
±
3.97
59.64
±
4.45
C/P
ratio
467.72
±
42.1
359.92
±
53.9
673.14
±
79.98
Specific
weight
(gr
cm
-3
)
1.09
±
0.02
1.12
±
0.08
135
±
0.04
Porosity
(%)
52.4
±
5.5
493
±
4.9
28.6
±
6.6
Germination
index
(%)
17
±3
21
±
5
16
±
9
Humics
(%)
1.03
±
0.08
1.18
±
031
0.92
±
030
E4/E6
ratio
1.00
±
0.05 0.95
±
0.07
1.10
±
0.13
S
2
S
2
(b.)
=
N
where
g,
is
the
standard
deviation,
Sad
is
the
adequacy
deviation
and
is
calculated
by
the
Eq.
(2).
Y
i
is
the
experimental
i
value,
Y,
is
the
estimated
i
value
from
the
model
determined,f
is
the
number
of
degrees
of
freedom,
and
N
is
the
number
of
trials.
As
far
as
the
determination
of
statistically
important
parameters
is
concerned,
the
procedure
mentioned
below
was
followed.
The
coefficient
devi-
ation
is
defined
by
Eq.
(3)
where
N
is
the
number
of
trials.
The
importance
of
the
coefficient
was
checked
by
Eq.
(4).
t
=
S(b3)
(4)
where
k
is
the
j
linear
coefficient.
"t"
should
follow
the
Student
dis-
tribution
for
importance
level
p
=
5%
and
degrees
of
freedom
those
of
the
deviation
S
2
(
Y).
After
the
mathematical
model
construction
and
the
determination
of
statistically
important
parameters,
an
ef-
fort
to
find
the
optimum
conditions
for
the
effectiveness
of
the
Fen-
ton
oxidation
treatment
of
wood-processing
industry
wastewater
was
made.
This
was
performed
through
a
steepest
ascent
method.
After
the
treatment
of
0MW
with
Fenton
treatment,
the
treated
ol-
ive
mill
wastewater
(TOMW)
with
the
produced
sludge's
from
the
Fenton
Process
were
proceed
for
further
treatment
in
two
several
systems:
(i)
in
lagooning
for
physical
evaporation
and
with
typical
red
beds
and
(ii)
with
co-composting
with
00SR
The
amount
added
to
the
system
was
equal
with
the
final
moisture
of
60
±
5%.
For
the
composting
of
the
00SR
with
the
TOMW
two
different
systems
were
used:
(a)
Compost
System
(CS1):
A
typical
windrow
system
of
3
m
length
and
1.5
m,
with
final
moisture
of
60
±
5%.
The
samples
were
aerated
using
an
aerated
air
force,
and
(b)
Compost
System
(CS2):
An
In-Vessel
reactor
of
1
m
3
active
volume
(Zorpas
2008).
The
thermophilic
phase
in
the
reactor
lasted
15
d.
The
temperature
in
the
center
of
the
reactor
was
about
60-65
°C
and
the
moisture
percentage
between
60
±
5%.
The
samples
were
aerated
using
an
aerated
air
force
(oxygen
concentration
range
in
the
reactor
was
between
5-8%).
A
temperature
indicator
controller
was
controlling
the
operation
of
the
fan
in
order
to
maintain
the
temperature
at
about
60
°C,
according
to
the
following
principle:
minimum
air
flow
(2.3
m
3
per
m
3
active
volume)
was
provided
at
low
temperature
(<30
°C)
and
maximum
air
flow
(28
m
3
per
m
3
active
volume
was
provided
at
high
temperature
(>60
°C).
The
minimum
airflow
corresponds
to
the
minimum
oxygen
demand
for
the
microorganisms
and
the
maximum
to
the
necessary
air
for
cooling.
After
the
thermophilic
period,
in
which
the
organic
mate-
rial
was
biodegraded,
the
compost
was
piled
to
an
enclosed
package
where
it
remained
for
about
four
months
to
mature.
The
fundamen-
tal
principle
of
a
co-composting
system
is
the
biodegradation
of
the
organic
matter
through
exothermic
aerobic
bioreactions
which
take
place
in
the
thermophilic
region
with
the
simultaneous
evaporation
of
the
moisture
of
the
wastewater
due
to
the
release
of
thermal
en-
ergy
(Jewell
et
al.,
1980).
As
a
critical
parameters
for
the
growth
of
microorganisms
and
bioreactions
are
the
oxygen
demand,
the
mois-
ture
(which
must
be
in
the
range
of
60
±
5%)
the
temperature
(which
must
be
retained
between
60-65
°C)
and
the
Carbon/Nitro-
gen
(C/N)
ratio.
4.
Results
and
discussion
Tables
2
and
3
present
the
physicochemical
characteristics
of
the
0MW
and
the
00SR
from
the
three
several
Olive
Mills.
As
indi-
cated
in
Table
2
the
COD
and
the
BOD
5
is
considering
very
high
which
causes
serious
environmental
problems.
The
higher
COD
presented
in
the
OMW-DL
which
is
127.4
±
36.3
mg
L
-1
,
follows
by
the
OMW-DP
which
is
at
122.9
±
34.5
mg
L
-1
and
the
OMW-DF
with
COD
at
118.3
±
32.1
mg
L
-1
.
The
total
humics
is
con-
sidered
to
be
very
low
(less
than
1.4
mg
L
-1
)
while
the
E4/E6
is
be-
low
5.
The
E4/E6
ratio
shows
the
characterization
of
humic
materials.
As
the
E4/E6
ratio
is
bellow
5,
the
samples
are
character-
ized
as
Humic
Acid
(whereas
if
the
ratio
is
above
5
the
sample
is
characterized
as
Fulvic
Acid),
(Zorpas
1999).
The
COD/BOD
ratio
ranges
from
2.98:1
to
4.05:1,
which
indicates
the
presence
of
poor
biodegradable
organic
compounds
and/or
toxic
ones
El-Gohary
et
al.
(2009).
The
G.I
is
presented
to
be
less
than
26
and
the
sub-
strate
is
characterized
as
very phytotoxic
both
for
the
0MW
and
for
the
00SR.
The
C/N
ratio
both
of
the
substrates
(0MW
and
00SR)
is
considered
to
be
at
very
satisfactory
levels
for
composting
process.
The
variation
of
the
EC
is
due
to
the
different
quality
of
the
water
use
in
the
production
line.
Similar
results
from
the
charac-
teristic
of
0MW
from
Geece
are
found
from
Gotsi
et
al.
(2005).
El-Gohary
et
al.
(2009)
mention
that
the
COD,
TOC
and
BOD
values,
ranged
from
102,900
to
207,300
mg
0
2
L
-1
,
from
30,000
to
93,000
and
from
78,528
to
135,400
mg
0
2
L
-1
,
respectively
from
an
OMW.
The
COD
reduction
is
up
to
65%
for
almost
all
the
treated
sampled
(3)
AA.
Zorpas,
C.N.
Costa/
Bioresource
Technology
101
(2010)
Table
3
Physicochemical
characteristics
of
mature
compost
(120
d).
7984-7987
7987
Parameters
CS1
CS2
A
Al
B
B1
Moisture
(%)
32.1
±
5.03
26.8
±
235
28.2
±
1.99
22.5
±
2.19
pH
7.2
±
0.05
7.7
±
0.03
7.7
±
0.03
7.6
±
0.01
Ash,
%
of
dry
matter
25.85
±
1.87
29.68
±
133
28.81
±
1.66
27.10
±
1.51
Organic
matter,
%
of
dry
matter
74.15
±
3.09
7032
±
4.12
71.19
±
2.99
72.90
±
1.97
Total
organic
carbon,
%
of
dry
matter
40.7
±
431
37.27
±
3.16
40.58
±
3.01
39.01
±
2.19
Total
Kjeldahl
nitrogen
(%)
1.13
±
0.16
133
±
0.22
130
±
0.14
1.44
±
0.11
Total
phosphorous
(%)
0.45
±
0.11
0.55
±
0.05
0.61
±
0.12
0.52
±
0.07
C/N
36.01
±
3.41
28.02
±
2.13
31.22
±
3.04
27.09
±
2.21
C/P
90.44
±
12.91
67.76
±
7.01
66.52
±
9.18
75.01
±
5.66
Humic
substances,%
of
dry
matter
5.84
±
1.09
635
±
0.97
7.04
±
1.13
7.15
±
0.88
Total
phenolic
compounds
(mg/kg)
212
±34
192
±
23
188
±
51
173
±
19
Germination
index
124
±
21
138
±
12
177
±
19
201
±
9
Grow
index
(%)
73
±
5
77
±
6
77
±
10
92±3
(62.35
±
8.03%).
Fenton
processes
are
suitable
to
treat
a
wide
vari-
ety
of
effluents
irrespective
of
their
concentration
and
origin
and
are
characterized
by
their
simple
and
versatile
operation.
As
olive
oil
manufacturing
industries
are
usually
small
plants
with
a
low,
seasonal
wastewater
flow,
a
small
Fenton
unit
would
suffice
to
cope
efficiently
with
the
effluents
produced.
Rivas
et
al.
(2001)
estimated
that
OMW
treatment
(15
mg
L
-1
of
inlet
COD
and
80-90%
COD
reduction
achieved
in
residence
times
between
1
and
8
h
depending
on
the
operating
conditions
employed)
by
Fen-
ton's
reagent
would
cost
USD
3.2
per
m
3
of
wastewater
treated
and
mg
L
-1
of
COD
removed.
This
value
is
greater
than
that
of
the
con-
ventional
biological
treatment
of
OME
by
about
an
order
of
magni-
tude
since
H
2
0
2
consumption
comprises
a
significant
fraction
of
the
operating
costs.
In
this
respect,
studies
are
needed
to
optimise
the
dosage
of
the
Fenton's
components
used,
thus
avoiding
waste
of
costly
chemicals
(Mantzavinos
and
Kalogerakis,
2004).
Table
3
shows
the
characterization
of
the
final
product
after
120
d
of
matu-
rity.
It
was
obvious
that
the
B1
sample
of
CS2
was
presented
with
better
characteristics
than
the
other
final
products.
Specifically,
the
B1
final
cured
compost
is
presented
with
pH
at
7.6
±
0.01,
Organic
Matter
at
72.90
±
1.97%,
TOC
at
72.9
±
1.97%,
TKN
at
1.44
±
0.11%,
TP
at
0.52
±
0.07%,
C/N
and
C/P
ratio
at
27.09
±
2.21
and
75.01
±
5.66
respectively,
total
humics
at
7.15
±
0.88%,
total
pheno-
lic
compounds
at
173
±
19
mg
kg
-1
while
the
G.I
is
at
201
±
9.
As
olive
oil
manufacturing
industries
are
usually
small
plants
with
a
low,
seasonal
wastewater
flow,
a
small
Fenton
unit
would
suffice
to
cope
efficiently
with
the
effluents
produced.
This
process
proved
to
be
effective
for
the
reduction
of
wastewater
pollution
load
and
its
detoxification.
After
this
implementation,
the
conven-
tional
biological
treatment
of
wastewaters
is
feasible
and
cost
effective.
Moreover,
further
wastewater
treatment
with
reed
beds
could
render
them
totally
recyclable.
The
proposed
approach
to-
wards
a
sustainable
solution
to
the
environmental
impacts
of
olive
oil
processing
includes
the
production
of
organic
fertilizer/soil
con-
ditioner
combined
with
the
effective
chemical
and
biological
oxi-
dation
of
wastewaters.
Hence,
the
Fenton's
reaction
appears
to
be
useful
for
reducing
toxic
phenolic
compounds
consequently
in-
creases
the
biodegradability
of
OMW.
Compared
to
other
AOPs,
Fenton's
reaction
presents
several
advantages.
H
2
0
2
is
environ-
mentally
friendly,
since
it
slowly
decomposes
into
oxygen
and
water.
Besides,
the
abundance,
lack
of
toxicity
and
ease
of
removal
from
water
makes
Fe
2
+
the
most
commonly
used
transition
metal
for
Fenton's
reaction
applications.
The
above
characteristics
make
compost
suitable
for
agricultural
requirements
and
suggest
that
it
can
be
used
as
an
effective
product
for
plant
growth
according
to
European
Guidelines
(European
Commission,
2005).
Very
inter-
esting
research
approaches
which
are
not
presented
in
this
re-
search
is
for
the
future
the
co-composting
from
the
total
waste
production
from
the
olive
oils
industry
in
Cyprus.
The
integrated
management
system
may
include
the
chemical-organic
sludge
produced
by
the
oxidative
process,
the
sludge
produced
by
the
bio-
logical
process,
the
olive
tree
leaves,
the
olive
stones
and
the
resi-
dues
from
the
reed
beds
for
the
production
of
an
ecological
soil
conditioner
with
very
good
control
nutrient
properties.
5.
Conclusions
From
all
the
above
it
can
be
concluded
regarding
the
pollution
problems
caused
by
olive
oil
production,
a
solution
based
on
the
principles
of
the
clean
technology
concept
could
be
the
detoxifica-
tion
of
wastewaters
and
the
composting
with
the
olive
oil
solid
res-
idues.
The
use
of
Fenton's
reaction
as
a
primary
treatment
of
OMW
enhances
the
efficiency
of
the
composted
material.
It
is
obvious
that
the
final
characteristics
of
the
composted
material
presented
with
a
very
good
soil
conditioner.
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