School of Environmental Engineering Technical University of Crete
Edible olives processing The olives usually are collected at different stages of maturity and then processed to eliminate the characteristic bitter taste, due to the glucoside oleuropein The table olives debittering process can be accomplished using two ways: - The “Chemical method” (Spanish/Californian style) - The “Natural method” (Greek style) Greek style School of Environmental Engineering Spanish/Californian style Technical University of Crete
Edible olives dibittering processes Chemical method Natural method (Spanish/Californian style) (Greek style) Treatment with NaOH solution, Direct fermentation in 6-10% brine followed by fermentation in 5-6% brine NaOH 0.8 ton wastewater per ton of olives 5 ton wastewater per ton of olives School of Environmental Engineering Technical University of Crete
Edible-olives fermentation Natural method Chemical method ~60% of polyphenols is removed ~90% of polyphenols is removed β -glucosidase Fermentation takes place in industrial Fermentation takes place in plastic barrels reactors from fiberglass School of Environmental Engineering Technical University of Crete
Edible-olives processing wastewater School of Environmental Engineering Technical University of Crete
Edible olives processing wastewater Natural method Lye produced after the treatment of olives with NaOH Chemical method School of Environmental Engineering Technical University of Crete
Characteristics of edible-olives processing wastewater High COD (7,500-25,000 mg/L) High BOD 5 (5,000-15,000mg/L) Relatively high TSS concentration (800-2,000mg/L) Moderate concentration of nitrogen (50-200 mg/L) Relatively high concentration of phosphate (50-200mg/L) High oil & grease content High concentration of polyphenolic compounds High conductivity High salinity Extreme pH (very high or very low) Dark color Wastewater characteristics depend on the process used School of Environmental Engineering Technical University of Crete
Common treatment practices Anaerobic Coagulation/flocculation Aerobic biological biological Oxidatio- Evaporation Photooxidation Edible-olives wastewater Combinations of the above have also been tried Co-processing in municipal wastewater facilities often results in plant destabilization Often the edible-olives wastewater is discharged illegally into natural receivers School of Environmental Engineering Technical University of Crete
Geopolymers Geopolymers (active clay sediments): Three-dimensionally cross-linking alumininosilicates amorphous inorganic materials Consist of various inorganic repeating units, such as: silico-oxide (-Si-O-Si-O-) silico-aluminate (-Si-O-Al-O-) ferro-silico-aluminate (-Fe-O-Si-O-Al-O-) alumino-phosphate (-Al-O-P-O-) Geopolymerisation: A relatively complex reaction (polycondensation) between aluminosilicate- containing powders (e.g. fly ashes and/or reactive clays) with alkali metal silicates or hydroxides Portland cement Geopolymer School of Environmental Engineering Technical University of Crete
Uses of geopolymers Uses of geopolymers: • Binding materials • Ceramics • Arts and demonization • Restoration of archeological findings • Fire resistance materials • Adsorption/encapsulation of wastes Use of geopolymers for wastewater treatment: • Irreversible adsorption of a large spectra of wastes (organic, inorganic, heavy metals) • Can be structured so to be adsorption-selective (eg: for heavy metals, organic wastes, radioactive wastes, etc School of Environmental Engineering Technical University of Crete
Geopolymer School of Environmental Engineering Technical University of Crete
Edible-olives processing wastewater treatment using the active clays sentiments (geopolymers) Flow equalization Removal of coarse solids pH adjustment Chemical oxidation Coagulation Adsorption on geopolymer Removal of sediment (clarification) Filtration of supernatant Polishing (photo-oxidadtion using nanocatalyst) Disinfection Process depends on wastewater characteristics School of Environmental Engineering Technical University of Crete
Process diagram for edible-olives wastewater treatment Filtrate Nano- catalyst H + Geopolymer Oxidation Coagulant or agent OH - Cl H 2 O 2 Light Inlet Rotary drum Equalization Geochemical pH tank reactor Chemical adjustment Outlet oxidation Air Polishing Filter tank Clarifier Air R Sludge Filtrate Dewatering School of Environmental Engineering Technical University of Crete Stabilized sludge
Application Edible olives production facility in Chalkiliki, Greece Capacity: 10,000 ton olives per year Method: partly “chemical”, partly “natural” process School of Environmental Engineering Technical University of Crete
Types of edible-olives wastewater Equalization tank School of Environmental Engineering School of Environmental Engineering Technical University of Crete Technical University of Crete
Reactor tanks School of Environmental Engineering School of Environmental Engineering Technical University of Crete Technical University of Crete
Geopolymer addition tank School of Environmental Engineering School of Environmental Engineering Technical University of Crete Technical University of Crete
Geopolymer inside the feeding silo School of Environmental Engineering School of Environmental Engineering Technical University of Crete Technical University of Crete
Filter press and sedimentation tank School of Environmental Engineering School of Environmental Engineering Technical University of Crete Technical University of Crete
Treatment efficiency IN OUT BOD 9450 10000 20 18 8760 8300 7500 8000 15 6000 mg/l mg/l 9 10 4000 5 2000 2 1 0 0 1 2 3 4 1 2 3 4 TSS OUT IN 100 93 1200 1120 1080 90 84 960 1000 900 80 70 800 60 mg/l mg/l 50 600 40 400 25 30 20 12 200 10 0 0 1 2 3 4 1 2 3 4
Treatment efficiency IN TN OUT 18 160 16 135 16 140 14 120 102 11 12 100 85 9 10 mg/l mg/l 69 80 7 8 60 6 40 4 20 2 0 0 1 2 3 4 1 2 3 4 P IN OUT 120 1,8 1,5 98 1,6 100 1,4 80 1,2 62 1 mg/l mg/l 55 60 0,8 40 0,5 0,6 40 0,3 0,4 20 0,1 0,2 0 0 1 2 3 4 1 2 3 4
Treatment efficiency IN Turbidity OUT 1200 2,5 980 2 1000 2 800 695 650 630 1,5 NTU NTU 600 1 400 0,5 200 0 0 0 0 0 1 2 3 4 1 2 3 4 Sludge leaching tests: Concentrations of dissolved organic carbon are by far below the limits set by the legislation School of Environmental Engineering Technical University of Crete
Treatment efficiency stage by stage TN 160 135 135 140 120 100 mg/l 80 BOD 60 10000 8760 40 9000 20 8000 7 7 7008 7000 0 6000 Inlet Chemical Geochemical Chemical mg/l 5000 oxidation processing refining 4000 3000 P 2000 70 1000 85 9 62 62 0 60 Inlet Chemical Geochemical Chemical 50 oxidation processing refining 40 mg/l 30 20 10 0 0 0 Inlet Chemical Geochemical Chemical oxidation processing refining School of Environmental Engineering Technical University of Crete
Cost The capital cost of a full geochemical wastewater treatment plant with capacity of 15,000 m 3 /yr has been calculated between 250,000 € The operation cost (including chemicals, geopolymer and energy) has been calculated between 2.7-3.2 € /m 3 Cost is competitive, taking into account the process stability and the fact that discharge limits can be achieved School of Environmental Engineering Technical University of Crete
Conclusions The use of active clay sediments process can achieve complete treatment of edible olives processing wastewater The process comprises by a series of sub-processes, including pH adjustment, chemical oxidation, coagulation, geopolymer reaction, clarification, filtration, photo-oxidation The capital and operational costs for small-medium olive processing faculty has been calculated as 250,000 € , 2.7-3.3 € /m 3 , respectively Wastewater treatment process should take into account recent technological achievements and the needs of the modern society School of Environmental Engineering Technical University of Crete
Thank you for your attention petros.gikas@enveng.tuc.gr School of Environmental Engineering School of Environmental Engineering Technical University of Crete Technical University of Crete
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