Chemical & Process Engineering ‘Engineering from Molecules’ Energy efficient microbubbles for aeration, flotation and other uses: wastewater aeration, dispersed air flotation, ozone dosing, digester/algal growth/carbon capture. Will Zimmerman Professor of Biochemical Dynamical Systems Chemical and Biological Engineering, University of Sheffield and Technical Director, Perlemax, Ltd. with Dr Hemaka Bandulasena and Dr Jaime Lozano-Parada, with Mr Kezhen Ying and Mr James Hanotu and special thanks to Professor Vaclav Tesar, Dr Buddhi Hewakandamby, and Mr Olu Omotowa (all formerly University of Sheffield researchers).
Transcript
Chemical &ProcessEngineering
‘Engineering from Molecules’
Energy efficient microbubbles for aeration, flotation and other uses: wastewater aeration, dispersed air flotation, ozone dosing,digester/algal growth/carbon capture.
Will ZimmermanProfessor of Biochemical Dynamical SystemsChemical and Biological Engineering, University of Sheffieldand Technical Director, Perlemax, Ltd.
with Dr Hemaka Bandulasena and Dr Jaime Lozano-Parada, with Mr Kezhen Ying and Mr James Hanotuand special thanks to Professor Vaclav Tesar, Dr Buddhi Hewakandamby, and Mr Olu Omotowa (all formerly University of Sheffield researchers).
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Outline
• Why microbubbles: mass transfer and flotation• Wastewater aeration• Potential for replacing dissolved air flotation• Algal growth / carbon capture / wastewater plant
integration => target energy positive and CO2 neutral• Ozone• Fluidic electricity generator
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Why microbubbles?
• Faster mass transfer -- roughly proportional to the inverse of the diameter• Flotation separations -- small bubbles attach to particle / droplet and the whole floc rises
Steep mass transferenhancement.
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Fluidic oscillator
Fluidic oscillatorNo moving parts switching
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Pilot scale: Experimental design
Suprafilt layout for 30m^3/h Master-slave amplifier system for fluidic oscillator
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Energetics: Power consumption
Oscillatory flow draws less power than steady flow at the same throughput!
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
With Oscillator
Without OscillatorWith Oscillator, Master (small) shut completely
Visualization studyand Frequency analysis
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Frequency of oscillation depends on feedback loop and air throughput
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Aeration: DO profiles, clear water Blow-up
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Delay time and dosage
0
1 TD C dt
T= ∫
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Summarized findings
• Visualization study • Oscillation frequency • power consumption: with maximum value of 18%
reduction at the best aeration configuration. • Clear water dissolved oxygen study: 3-4 fold better
dosage at 83% of the design volumetric flow rate.• Pilot plant trial with UU in planning stages• SBR planned next in Rosslare – two basins with
automatic control.
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Potential for dissolved air flotation (DAF) plant
• Potentially eliminate recycle flow and saturator load (90-95% electricity cost)• Uses blowers not compressors/saturators (much lower capital)• Cheap materials for retrofit with fluidic oscillators introduced in the plumbing
and manifolds to diffuser bank for dispersal.
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Microporous diffusers
Fine mist of bubbles rising from Micropore Technologies Metallic membrane diffuser
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Field trial campaign
• Agreed with UU and AWS and AECOM Design Build (Brenda Franklin) to trial the technology in a single DAF cell at Padfield
• 12m2 of surface area available for microporous diffuser insertion for retrofit. Unit instrumented to measure performance and to be outfitted with visualization equipment.
• Tune performance in operating parameters – chiefly air throughput rates, water flow rate (~cm/s) and oscillation frequencies.
• Model data from performance studies for engineering design parameters (number of plate diffusers, placement, flow rates).
• Gain operational experience – identify potential problems, risks, failure modes -- to plan maintenance regime.
• Assess CAPEX and OPEX requirements
Microporousdiffuser
Growing algaewith microbubbles
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Ozone plasma microreactors
• How ozone disinfects in water solutions.• The ozone plasma microreactor in the lab• How to get the ozone off the chip? Microbubbles!• Prototypes• Field trial campaign
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Ozone Kills!
Ozone dissolves inwater to producehydroxyl radicals
Hydroxyl radical attacks bacterial cell wall, damages it by ionisation, lyses the cell (death) and finally mineralises the contents.
One ozone molecule kills one bacterium in water!
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Ozone plasma microreactor in the lab.Upper plate
Lower plate
Electrodes
Electrical connection
Fibre optics
Chipholder construct
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Microfluidic onchip ozone generation
Our new chip design and associated electronics produce ozone from O2 with two key economic features:
1. Low power. Our estimates are a ten-fold reduction over conventional ozone generators.
2. High conversion. The selectivity is double that of conventional reactors (30% rather than 15% single pass).
Additionally, it works at atmospheric pressure, at room temperature, and at low voltage (170V, can be mains powered).
Emission UV-Vis spectrum of exit gas with clear O3 signature. Analysis suggests 30% conversion at
temperature 350K.
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Plasma disks
• 25 plasma reactors each with treble throughput over first microchip
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Dosing lance prototypes
Axial view of the old lanceWith 8 or 16 microdisc reactors
New lance = 70 microdisc reactorsQuartz for UV irradiation
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Corporation cock assembly
Ball valve External assembly.
Valve control to toggle for flow/no flow
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Dual ozone-UV prototype design
New lance = 70 microdisc reactorsQuartz for UV irradiation
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Potential markets
• Water purification (municipal)• Waste water – organics removal• Waste water – disinfection before release• Sterilization (medical, biotech, pharmaceutical)• Distributed / remote / portable water purification• Ventilation system sterilization• Gas analysis (ozonolysis) and sensors• Biomass treatment and biofuels co-products Planning trials with UU (priority substances) and AWS
(pesticide removal)
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Air lift loop bioreactor design
Schematic diagram of an internal ALB with draught tube configured with a tailor made grooved nozzle bank fed from the two outlets of the fluidic oscillator. The microbubble generator is expected to achieve nearly monodisperse, uniformly spaced, non-coalescent small bubbles of the scale of the drilled apertures.
• Journal article has won the 2009 IChemE Moulton Medal for best publication in all their journals.• Designed for biofuels production• First use: microalgae growth• Current TSB / Corus / Suprafilt grant on carbon sequestration feasibility study on steel stack gas feed to produce microalgae.
Chemical &ProcessEngineering ‘Engineering from Molecules’
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
ALB for algae growth
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Results
Rapid pH dropPotential licensee for carbonSequestration organic chemistry
30% higher relative growth rate with only60 minutes per day dosing TSB / Corus / Suprafilt project for continurous dosing.
Best poster 6th Annual bioProcessUKConference, Nov 2009, York.
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Current programme of field trials
• Corus: steel plant algal culture• Aecom: separation/harvesting• Air lift loop bioreactor development
for biofuels
Approximately 1 cubic metrecube design with0.8 m2 square ceramic microporousdiffusers.
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Prospects for process integration / intensification for WWTW flowsheet re-design
Key concept: Microbubble dosing will be cheap, but allow access to all process gases.
Anaerobic digestor:CO2 dosing and CO2/CH4
stripping Accelerates biochemistryCHP provides CO2 for
algal growthAnammox process Stage 1 Aerobic (air
dosing)Stage 2 Anaerobic CO2
dosing and CO2/N2stripping
Result: Accelerate biochemistry of all processes by reactive extraction. Influence production by nutrient dosing rate. Grow algae for biomass / biofuel. Sequester CO2. Provide O2.
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
Potential microbubble markets• Dispersed air flotation for solids removal in water and
3-fold higher dosing rates on retrofit)• Algal biomass / bioenergy production (partner Corus,
>30% extra biomass from CO2 microbubble dosing)• Wastewater treatment processes integration and
intensification: aeration, digestion, de/nitrification, algal growth. Targets: smaller footprint; carbon and energy neutral!
• Ozone dosing from a plasma microreactor dosing lance• Air lift loop bioreactor development for biofuels• Heterogeneous chemical and bioreactor engineering,
gas-lift oil recovery, oil-water separations, heat transfer
Chemical &ProcessEngineering ‘Engineering from Molecules’
‘Engineering from Molecules’
More Acknowledgements
• TataSteel: Bruce Adderley, Mohammad Zandi and more.• Suprafilt: Graeme Fielden, Jonathan Lord, and Hannah
Nolan• Micropore Technologies: Mike Stillwell• HP Technical Ceramics: Tim Wang• AECOM DB: Brenda Franklin, Ben Courtis, Hadi Tai, Yen
Chiu• Yorkshire Water: Martin Tillotson, Ilyas Dawood• UoS: Jim Gilmour, Raman Vaidyanathan, Simon Butler,
Graeme Hitchen, Adrian Lumby, Stuart Richards, Clifton Wray, Andy Patrick
• Yorkshire Forward, TSB, EPSRC, SUEL, Perlemax• Royal Society Brian Mercer Innovation Award, EPSRC
