of a high rate thermophilic anaerobic upbr reactor for...

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


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


Introduction


Introduction Table 2: Chemical characteristics of OMW.


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


Introduction

Environmental impacts of OMW:

•Soil pollution and phytotoxicity

•Water pollution

•Air pollution



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


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


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)


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


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



Experiment A B C D






Experimental Eθ

High dispersion

Low dispersion

N‐CSTR in series



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







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


Thermophilic anaerobic treatment of OMW usingthe UPBR Reactor ‐ Results


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


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

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