University of PatrasMSc in Green Chemistry and Clean Technologies
Department of Chemistry in collaboration with theDepartment of Chemical Engineering
21‐23 May 2015, Athens
Laboratory of Biochemical Engineering & Environmental Technology
K. Tsigkou, A. Kotoulas, A. Kopsahelis, M. Kornaros
Development of a high‐rate thermophilic anaerobic UPBR reactor for the treatment of three‐phase olive mill wastewater
Huge quantities of olive oil are produced annually worldwide. Greeceis ranked third, after Spain and Italy. It is estimated that there are25.000 olive mills globally, 3.500 of them are located in Greece.
1.500.000
500.000
300.000
198.000
191.000
180.000
120.00074.00025.000
Olive oil production (t)1
Spain
Italy
Greece
Syria
Turkey
Tunisia
Morocco
Portugal
Argentina
1Koutrouli et al., 20082Tzouvara et al., 2010
Prefecture of Greece Olive mills per prefecture
Messinia 270
Herakleion 260
Ilia 158
Chania 138
Achaia 133
Korfu 123
Rethimnon 98
Aitoloakarnania 89
Introduction
21‐23 May 2015, Athens
Table 1: Olive mills located in prefectures of Greece , known for huge amounts of olive oil production.2
Main processes of oil extractionWashing
Pressing process 3‐phase centrifugation
Crushing/ Malaxing
olives
Crushing/ Malaxing
Water
Horizontal centrifugationPressing
Olive oil + water pomace pomaceLiquid Olive oil
2‐phase centrifugation
WaterCrushing/ Malaxing
Horizontal centrifugation
2‐phase OMW
Water
Olive oil Olive oil
Vertical centrifugation
OMWW
Decantation
OMWW
Oil washing
Olive oil
Dermeche et al., 2013
21‐23 May 2015, Athens
Introduction
21‐23 May 2015, Athens
Introduction Table 2: Chemical characteristics of OMW.
Dermeche et al., 2013
ParametersOlive oil by‐products
OMWWSolid residueOlive cake 2‐phase OMW
Pulp (%) 12‐35 10‐15Olive‐stone (%) 15‐45 12‐18Dry matter (%) 6.33‐7.19 87.1‐94.4Ash(%) 1 1.7‐4 1.42‐4pH 2.24‐5.9 4.9‐6.8Electrical conductivity (dS/m) 5.5‐10 1.78‐5.24Total carbon (%) 2‐3.3 29.03‐42.9 25.37Organic matter (%) 57.2‐62.1 85 60.3‐98.5Total organic carbon (g/L) 20.19‐39.8Total suspended solids (g/L) 25‐30Mineral suspended solids (g/L) 1.5‐1.9Volatile suspended solids (g/L) 13.5‐22.9Volatile solids (g/L) 41.9Mineral solids (g/L) 6.7Volatile acidity (g/L) 0.64Inorganic carbon (g/L) 0.2Total nitrogen (%) 0.63 0.2‐0.3 0.25‐1.85P(%) 0.19 0.03‐0.06 0.03‐0.14K(%) 0.44‐5.24 0.1‐0.2 0.63‐2.9Na (%) 0.15 0.02‐0.1Ca (%) 0.42‐1.15 0.23‐1.2Mg (%) 0.11‐0.18 0.05‐0.17Fe (%) 0.26 ±0.03 0.0526‐0.26Cu (%) 0.0021 0.0013‐0.0138Mn (%) 0.0015 0.0013‐0.0067Zn (%) 0.0057 0.0010‐0.0027Lipids (%) 0.03‐4.25 3.5‐8.72 3.76‐18.0Total phenols (%) 0.63‐5.45 0.2‐1.146 0.4‐2.43Total sugars (%) 1.5‐12.22 0.99‐1.38 0.83‐19.3Total proteins (%) 3.43‐7.26 2.87‐7.2Chemical oxygen demand (g/L) 30‐320Biological oxygen demand (g/L) 35‐132
21‐23 May 2015, Athens
Introduction
Environmental impacts of OMW:
•Soil pollution and phytotoxicity
•Water pollution
•Air pollution
Dermeche et al., 2013
21‐23 May 2015, Athens
Introduction
Processes for OMW treatment1,2:
•Physical•Filtration•Settling•Micro‐, ultra‐, nano‐filtration•Reverse osmosis
•Thermal•Combustion•Pyrolysis•Distillation•Evaporation
1Dermeche et al., 20132Kornaros , 2013
•Physicochemical•Oxidation•Neutralization•Electro‐Fenton•Ozonation
•Biological•Anaerobic processes•Aerobic processes•Mixing and digestion•Enzymatic
21‐23 May 2015, Athens
Introduction
Theofilou et al., 2011
By the anaerobic treatment…
a low cost process with low energy demand is achieved
wastewater with high COD values are able to be treated
high yields in energy production may be achieved
a minimum use of chemicals is required
low space requirements
21‐23 May 2015, Athens
Experimental set up
UPBR Reactor
Total volume: 6.2 L
Working volume: 5 L
Plexiglas
Thermophilic conditions (55οC)
Recycling pump
Plastic biomass carriers K5 by Anoxkaldness (withprotected surface of 800 m2/m3)
21‐23 May 2015, Athens
Hydrodynamic study
Nardi al., 1999
• Tracer: NaF solution
• Pulse injection
• HRT : 1,4 days
• Sampling : Every 1 h
• Thermophilic conditions
Table 3: Definition of the variables used for obtaining residence time distribution function (Eθ) against dimensionless mean residence time (θ)
Table 4: Single parameter hydrodynamic theoretical models
21‐23 May 2015, Athens
Hydrodynamic study ‐ Results
Experiment A B C D
Experimental conditions
– recycling stream– biomass carriers
+ recycling stream– biomass carriers
– recycling stream+ biomass carriers
+ recycling stream+ biomass carriers
21‐23 May 2015, Athens
Hydrodynamic study ‐ Results
Experiment A B C D
Experimental conditions
– recycling stream– biomass carriers
+ recycling stream– biomass carriers
– recycling stream+ biomass carriers
+ recycling stream+ biomass carriers
Experimental Eθ
High dispersion
Low dispersion
N‐CSTR in series
21‐23 May 2015, Athens
Hydrodynamic study ‐ Results
ExperimentN
(theoretical)N
(LSF)Correlation coefficient
A 3.38 3 0.602B 1.98 1 0.289C 3.65 5 0.277D 1.94 1 0.475
Experiment A B C D
Experimental conditions
– recycling stream– biomass carriers
+ recycling stream– biomass carriers
– recycling stream+ biomass carriers
+ recycling stream+ biomass carriers
21‐23 May 2015, Athens
Microorganisms’ acclimatization to thermophilic conditions
•Mixed cultures collected from the effluents of amesophilic UASB reactor, which was alsosuccessfully deployed in treating 3‐phase OMW•3L Erlenmeyer flask•Thermophilic conditions (55oC)•Feed: OMW diluted with tap water•HRT: 30 days
21‐23 May 2015, Athens
Conclusions
The hydrodynamic characterization of the UPBR reactor exhibited mainly itsnon‐ideal CSTR operation, which can however be simulated by 1, 3 or 5 N‐CSTR inseries, with reasonable accuracy.
An active thermophilic culture of anaerobic microorganisms originating fromthe effluents of a mesophilic UASB reactor could be efficiently acclimated tobioconvert diluted (1:1) OMW to biogas.
The UPBR reactor was operated treating OMW efficiently at two HRTs, namely25 d and 14 d.
Concerning the UPBR’s efficiency in COD and phenolics removal the maximumachieved yields were 73.7% and 59.5% for the biodegradation of phenoliccompounds and 93.0% and 84.9% for the total organic constituents, whenoperated at the HRTs of 25d and 14d respectively.
The average reached yields were 0.23 L CH4/g t‐CODrem and 0.16 L CH4 /g t‐CODrem, measured at STP conditions for each HRT at steady‐state.
Investigation by further decreasing the HRT is ongoing in the thermophilicanaerobic OMW treatment in the UPBR reactor.
University of PatrasMSc in Green Chemistry and Clean Technologies
Department of Chemistry in collaboration with theDepartment of Chemical Engineering
21‐23 May 2015, Athens
K. Tsigkou, A. Kotoulas, A. Kopsahelis, M. Kornaros
Development of a high‐rate thermophilic anaerobic UPBR reactor for the treatment of three‐phase olive mill wastewater
Thank you for your attention…