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Environmental impacts relative to soil quality caused from the disposal of olive oil mills’ wastes
Case study : A municipality in Crete, Greece
M. Doula, V. Kavvadias, S. Theocharopoulos, P. Kouloumbis, NAGREF- Soil Science Institute of Athens
D. Ikonomou, D. ArapoglouNAGREF- Institute of Technology of Agricultural Products
The olive oil tree is amongst the oldest known cultivated trees inthe world while the consumption of olives and olive oil is believedto bring health, however, the side products (wastewaters-OOMWand solid wastes-SW) from their production and treatment couldimpact environment negatively if no precautions are taken.
It is estimated that there are 600 million productive olive trees onthe planet, occupying a surface area of 7 million ha. TheMediterranean region accounts for not less than 97% of the worldproduction Among European countries, but also worldwide, Spainand Italy are the two leaders in olive oil production, whereasGreece holds the third place.
The annual oil mills waste production of Mediterranean olive-growing countries is estimated to ranging from 7 million to over30 million m3, depending on annual olive production. The averagetotal production amounts approximately to 10x106-12x106
m3/year and occurs over a brief period of the year (November-March).
Annual olive oil Production in Mediterraneanfor the main olive oil-productive Countries
Country 2000(x103t)
2001 (x103t)
2002(x103t)
2003(x103t)
2004(x103t)
2005(x103t)
2006(x103t)
2007(x103t)
Spain 962,4 1.412 836,9 1.449 1.005 820,6 1.139 1.326
Italy 507,4 573,5 574,9 600,5 794,6 671,3 626,8 590,2
Greece 406,4 302,2 381,6 374,9 321,3 386,4 400,6 394,7
Tunisia 115,0 30,0 72,0 280,0 130,0 210,0 170,0 194,9
Portugal 26,0 35,0 31,0 36,5 50,1 31,8 51,8 39,0
1oo Kg olives
1oo-120 Kg wastewater
1 Kg olive oil
5 Kg wastewater
58% of mills dispose wastes in streams
11,5% of mills dispose wastes in sea and rivers
19,5% of mills dispose wastes on soil
It is estimated that :
Parameter Press 3-phase
Total solids, g/l 99,7 63,5Total Suspended Solids,g/l 4,51 2,80Total Volatile solids, g/l 87,2 57,4Ash, g/l 9,69 6,13Total Organic Carbon, g/l 64,1 39,8Total Kjeldahl Nitrogen, g/l 1,15 0,76Phosphorous (P2O5), g/l 0,87 0,53pH 4,50 4,80BOD5, mg/l 68.700 45.500COD, mg/l 158.000 92.500Specific Weight, g/cm3 1,05 1,05Conductivity, mmhos/cm 18,0 12,0Total Sugars, g/l 25,9 16,1Fats and Oils, g/l 2,80 1,64Polyalcohols, g/l 4,75 3,19Total Phenols, g/l 17,2 10,6Tannins, g/l 6,74 4,01Potassium (Κ2Ο), g/l 3,77 2,37Sodium (Na2O), mg/l 406 243Calcium (CaO), mg/l 382 271Fe (FeO), mg/l 48,3 32,0Magnesium (MgO), mg/l 74,0 50,0Silicon (SiO2), mg/l 28,6 18,0Total Sulfur, mg/l 101 63,0Total Chlorine, mg/l 219 124Mn, mg/l 18,2 12,0Zn, mg/l 19,7 12,0Cu, mg/l 10,50 6,00
Parameter (%) Press 3-phaseMoisture 27,21 50,23Fats and Oils 8,72 3,89Proteins 4,77 3,43Total Sugars 1,38 0,99Cellulose 24,14 17,37Ash 2,36 1,70Lignin 14,18 10,21Kjeldahl Nitrogen 0,71 0,51Phosphorous (P2O5) 0,07 0,05Total Phenols 1,146 0,326Potassium (Κ2Ο) 0,54 0,39Calcium (CaO) 0,61 0,44Total Carbon 42,90 29,03C/N ratio 60,79 57,17C/P ratio 588,0 552,9
Parameter Public sewernetwork
Streamsrivers
Sea Soil
pH 6-9 6-9 6-9 6-9Temperature (οC) 35 28 35 35Dissolved Oxygen(mg/l) - 3 - 3BOD5 (mg/l) 500 20 40 40COD (mg/l) 1000 120 150 120Suspended Solids (mg/l) 500 50 40 40Fats and Oils (mg/l) 40 5 20 2Kjeldahl Nitrogen (mg/l) 25 10 15 7Nitrates (mg/l) 20 4 20 5Phosphorous (mg/l) 10 0,2 2 2Total dissolved solids (mg/l)
3000 1000 1500 3000
Table 1 : Typical composition of wastewaters Table 2 : Characteristics of the olive oil processing solid wastes
Product Press 3-phase
2-phase
Olive oil 214 212 200
Wastewaters 920 1.670 -
Solid residues 323 462 800
Table 3 : Olive oil and wastes production per 1000 kg of olives processed
Table 4 : National Environmental Quality Standards for wastewater disposal in relation to each receptor apply
Source : Vlyssides et al., (1989-2002)
2009 - 2012
Co-funded by European Commission within the framework of LIFE+ Program.
Total Budget : 1.628.911 €
Beneficiaries
•NAGREF-Soil Science Institute of Athens•Technical University of Crete•Institute of Mediterranean Studies
•CERSAA-Centro Regionale diSperimentazione e Assistenza Agricola
•CEBAS- Centro de Edafologia y BiologiaAplicada del Segura
•Development and dissemination of innovative, environmentfriendly, low cost technologies for the protection of soil andwater pollution from olive oil mills’ wastes.
Project Objectives PROSODOL
•Establishment of an info-library/knowledge-base system toassess environmental impacts from olive oil mills’ wastes toMediterranean region.
•Facilitate the implementation of Soil Thematic Strategy in areas closeto olive oil mills.
•Design, implementation and support a monitoring system for theassessment of the soil and water quality affected directly or indirectlyfrom oil mills’ activities in relation to factors pressures and responses.
•Identification of potential safest uses in the agricultural sector ofolive oil mills’ wastes and its possible contribution to agriculturalproduction.
Design, implementation and support a monitoring system for theassessment of the soil and water quality affected directly or indirectly fromoil mills’ activities in relation to factors pressures and responses.
SOIL
Greek Implementation Area : Crete, Municipality of Nikiforos Fokas
Total area of 95m2, 21 Villages, 6600 residents
Geological formations are mainly identified as limestones, dolomites and marbles
Soils are slightly alkaline to alkaline (pH 7.3- 8.3) , clay or silty clay in texture and very rich in carbonates (50-60% CaCO3)
Three active olive oil mills (3-phase system with continuous centrifuge extraction systems) and two inactive for more than 5 years
Disposal areas contain ponds which were built by excavating the superfacial material of soil and by heaping excavating materials around the pond to form retaining walls. Protective impermeable membranes or other protective media were not used
From the five targeted areas, three will be presented.
NF1 : is a common disposal area, located in a field with slope of almost 10%. No surface disposal, the movement of wastes’ constituents is due to gravity
NF4 : is very large field with two ponds, of almost 5% slope. The owner disposes waste on soil through a pipe.
NF6 : is inactive for more than five years while it was used as disposal area for more than 20 years
Soil sampling took place 1 month after the completion of wastes disposal, between 6th and 9th May 2009.
Samples were collected from different distances from the ponds and depths of 0-25cm, 25-50cm, 50-75cm, 75-100cm, 100-125cm ,125-150cm and 150-175cm.
Samples were collected from inside the ponds at different depths (0m)
SAMPLING
The preparation of samples for analysis was performed according to ISO 11464:2006 method. Laboratory determinations were performed according to the methods usually used for soil characterization.
CHEMICAL ANALYSES
Particle size distribution, pH, Electrical Conductivity (EC) , organic matter (OM), total N, available phosphorous , Cation Exchange Capacity (CEC),exchangeable K, Ca, Na and Mg, water soluble Na, available Mn, Fe, Cu and Zn, Boron, Cl- , SO4
2-, PO43- ions by water extraction, Total
Polyphenols content.
0
0,5
1
1,5
2
2,5
3
0m 1m 3m 4m 25m
50m
75m
90m
105m
Control
Surface Disposal
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
0m 15m
0-25cm25-50cm50-75cm75-100cm100-125cm125-150cm150-175cm
Former Disposal AreaNF6
Measured in paste extract
Electrical Conductivity, mS/cmActive Disposal Area
NF4
41,62
0
2
4
6
80m 1m 2m 4m 25
m
50m
75m
90m
105m
Cont
rol
0
0,5
1
1,5
2
2,5
3
3,5
0m 15m
0-25cm
25-50cm
50-75cm
75-100cm
100-125cm
125-150cm
Determined by dichromate oxidation
0
5
10
15
20
25
0m 2m 4m 10m
12m
Cont
rol
Organic Matter, %
Former Disposal Area, NF6
Active Disposal AreasNF4
NF1
Surface Disposal
0
1
2
3
4
5
6
7
0m 1m 3m 4m 25m
50m
75m
90m
105m
Cont
rol
0
1
2
3
4
0m 15m
0-25cm25-50cm50-75cm75-100cm100-125cm125-150cm150-175cm
Former Disposal Area, NF6
Total Nitrogen (Kjeldahl), mg/g Active Disposal Area
NF4
Surface Disposal
According to ISO 11261:1995
>2.5mg/g : very rich
0
50
100
150
200
250
300
350
0m 1m 3m 4m 25m
50m
75m
90m
105m
Cont
rol
0
40
80
120
160
200
0m 15m
0-25cm
25-50cm
50-75cm
75-100cm
100-125cm
125-150cm
150-175cm
Extracted with sodium hydrogen carbonate (ISO 11263: 1994)
Available Phosphorous , mg/kg
Active Disposal AreaNF4
Surface Disposal
Former Disposal Area, NF6
25-45 ppm : very much sufficient
0
2
4
6
8
10
12
0m 1m 3m 4m 25m
50m
75m
90m
105m
Cont
rol
0
2
4
6
8
10
0m 15m
0-25cm
25-50cm
50-75cm
75-100cm
100-125cm
125-150cm
150-175cm
Extracted with Barium Chloride (ISO 11260:1994)
Exchangeable Potassium , cmol/kg Active Disposal Area
NF4
Surface Disposal
Former Disposal Area, NF6
3.8-6.4 cmol/kg : sufficient
450
0
20
40
60
80
100
120
140
160
0m 1m 3m 4m 25m
50m
75m
90m
105m
Cont
rol
0
10
20
30
40
50
60
70
0m 15m
0-25cm
25-50cm
50-75cm
75-100cm
100-125cm
125-150cm
150-175cm
Extracted with Methonol
Total Polyphenols, mg/kg Active Disposal Area
NF4
Former Disposal AreaNF6
Surface Disposal
0
5
10
15
20
25
30
35
40
0m 1m 3m 4m 25m
50m
75m
90m
105m
Cont
rol
0
5
10
15
20
0m 15m
0-25cm25-50cm50-75cm75-100cm100-125cm125-150cm150-175cm
Extracted with DTPA(ISO 14870:2001)
Mn(IV) reduced to Mn2+
Available Mn, mg/kg Active Disposal Area
NF4
Surface Disposal
Former Disposal Area, NF6
0-5 ppm : very low5-15 ppm : low15-30 ppm : moderate30-50ppm large> 50 ppm : very large
0
50
100
150
200
250
300
350
0
50
100
150
0m 15m
0-25cm25-50cm50-75cm75-100cm100-125cm125-150cm150-175cm
Extracted with DTPA(ISO 14870:2001)
Fe(III) is reduced to Fe(II)
Fe(II) + quinones Fe3+
0
100
200
300
0m 2m 4m 10m
12m
Cont
rol
Available Fe, mg/kg Active Disposal AreasNF4
NF1
Former Disposal AreaNF6
Surface Disposal
> 50 ppm : very large
ConclusionsDisposal of untreated OOMW at evaporation ponds without using protective materials has significant effect on chemical properties of soil close to ponds
•Enhanced Nitrogen content
Soil samples collected one month after the completion of wastes disposal are characterized by :
•Enhanced Organic Matter content, but for the cases of direct disposal on soil
•Increased Electrical Conductivity
•Enhanced Polyphenols content
•Increased of available Fe and Mn contents
•Significant increase in exchangeable K content
Inactive disposal area is characterized by normal Organic Matter and Nitrogen contents while exchangeable K; available Mn and Fe, polyphenols, phosphorous and EC remain high
•Significantly large Phosphorous amounts