spent caustic recovery dundalk brewery, liquid effluent reduction using membrane technology, diageo...
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Spent Caustic Recovery Dundalk Brewery
Liquid Effluent Reduction using Membrane Technology
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Caustic Recovery Project
• Project Implemented in 2 distinct Phases
• Phase 1Pilot plant feasability/case study on recovery and reuse of (CIP) Cleaning SolutionsProject Run by FDT Ireland Limited
• Phase 2 Implementation of Spent Caustic recovery PlantProject Run by Diageo Ireland Limited
• Both phases received funding from the EPA through the Cleaner Greener Production Programme
Membrane Filtration
Process in which liquid and some solutes in solution can be selectively removed through semi permiable membranes, by driving the liquid under pressure across the membrane.
Filtration OptionsMicrofiltration 0.05 to 10 µmUltrafiltration 2 to 100nmNanofiltration 0.5 to 3nmReverse Osmosis
Concentrate/ Retentate% Unfiltered feed solution containingretained suspended or disolved material
FeedSolutionContainingSuspendedAnd disolvedmaterials
Permeate/Filtrate% of filtered feedContainingtransmittedmaterial
MF, UF, NF, RO
Nanofiltration
A pressure driven membrane process in which a substance with molecular weight of <250 Da is pased through the membrane as filtrate and substances of > 250 Da is rejected.
Water NaOH Salts Sucrose ProteinsSuspended
Solids
Filter Membrane
Water NaOH Salts
Proteins, Sucrose and Suspended Solids Cannot Pass through membrane.
Caustic Solution passes through membrane and can be recovered.
Why Nano Filtration
Offers lowest level of impurities in the filtrateClear caustic filtrate with all colour impurities removedCaustic recovery possible at usable concentration and temperatureGreater than 90% volume recoveryGreater than 90% BOD Reduction/ ConcentrationCalcium and Carbonate reduction between 80 and 90%
Selection of Koch Membrane
• Koch nanofiltration membranes were selected after trials for the following reasons• pH range 0 – 14 • Molecular weight cut-off 250Da• Operating temperature 70 deg C• Asymmetrical crossflow membrane formation
MembraneMembrane
Conventional Membrane structure Koch Membrane Structure( Perpendicular flow filtration ) ( Crossflow filtration )
Permeate Permeate
Spiral Membrane
Spiral membranes are produced by winding consecutive layers of feed spacer, membrane and permeate collection channel around a perforated central pipe which collects the permeate
Feed solution is pumped from the batch tank and then flows into one end of the spiral membrane under high pressure.
The material which can pass through the membrane collects in the central permeate pipe.
The remainder of the feed solution exits the membrane unit and returns to the batch tank.
Feasability Study Findings
• CIP Caustic Recovery• Caustic Solutions for all areas can be successfully filtered through
membranes.• Caustic concentration is not reduced during Filtration• EDTA concentration is however significantly reduced.• EDTA is a sequestering agent added to caustic to improve its cleaning
properties.
• Conclusion• EDTA would have to be added to the recovered caustic before it could be
reused for Vessel and Line cleaning.• As brewery CIP systems are distributed across the site this is not a
commercially viable option.
• PVPP regeneration caustic reuse is possible and commercially viable as EDTA is not required during the regeneration process.
Beer Filtration Process Overview
Bright Beer Filtration.After primary filtration and before beer is transferred to Bright Beer Tank ready for later packaging beer can be filtered using a filtration aid called PVPP.The PVPP removes the protein poly-phenols which can cause haze in beer over time.The PVPP used in the process can be used repeatedly once it is regenerated using a 2% caustic solutionAfter regeneration the caustic used is dark in colour and contaminated with the poly-phenol material removed from the beer.Prior to implementation of recovery project this caustic was discharged to drain.
Plant Schematic
Spent
10 m32% NaOH65-70°C
PVPP Regen
Purified Hot Caustic (Permeate)
Organic Waste to Discharge
SelRO® Unit
Clean
10 m32% NaOH65-70°C
Caustic Caustic
Caustic Recovery ProjectFinal Production Skid
Recovery Plant was constructed and tested off site and delivered in skid format for easy integration into filtration process area.Plant has been in full operation since September 2005
Pre-FilterFeed
PermeateBreakTank
Water & Acid
Membranes
Flow Totaliser
Local Control Panel
Tank Level & TemperatureControl
Operational Monitoring
The graph shows the performance of the membrane plant.A typical filtration takes 8-9 hours and the spent caustic stream is typically concentrated up by values of between 10-12 times.
The graph shows how the VCF typically changes during a normal filtration run.If the flux rate falls to low levels early during a filtration run, it is a sign that the membrane requires cleaning.
VCF and flux rate during batch process.
Change in spent caustic tank volume during typical batch process. .
Feed solution from PVPP filter Clarified caustic from membrane plant.
Implementation Experience
There were no major obstacles in the implementation of this project.The skid format chosen for implementation facilitated quick and seamlessintegration of the plant into the existing process.Pre-filter on the membrane filtration unit feed solution.
Initially a cartridge type filter was installed.Replaced with polypropylene depth filters which could be removed, washedand reused.
Estimated membrane replacement cycle has been exceeded by 100% and plantcontinues to operate within specification.
The Annual Environmental Savings Achieved.
• Water Volume Reduction 1350m3 0.5% • Steam Consumtrion Reduction 129t 0.5%• Bulk Caustic 45% 30m3 26%• Bulk Acid 45% 15t 42%• Effluent Volume Reduction 1350m3 0.7%• BOD Reduction 15660Kg 2.2%
• Project Payback Period Originally Estimated at 2.6 Years• After 20mths it has already paid back
Other Possible Applications
• Food• Recovery and Reuse of Acids and Caustic from CIP Streams
• Pharmaceuticals• Concentration of Intermediates and Antibiotics in presence of Organic
Solvents
• Chemicals• Reduction of COD from Effluents;• Desalination of Dyestuff;• Removal of Heavy Metals from acids; • Recovery of Catalysts from Organic Solvents;
• Textiles• Color Removal• Caustic Recovery
Conclusion.
• Membrane filtration can be an economically viable process for the seperation for recovery of alkaline solutions
• Production scale plants can be run with longterm stability while requiring minimum operational and maintenance input
For Further Information
Declan Grennan, FDT [email protected]
Robbie Linehan, Diageo [email protected]