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).

Chemical & Process Engineering ‘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 CO 2 neutral Ozone Fluidic electricity generator

Chemical & Process Engineering ‘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 transfer enhancement.

Chemical & Process Engineering ‘Engineering from Molecules’ Fluidic oscillator No moving parts switching

Chemical & Process Engineering ‘Engineering from Molecules’ Pilot scale: Experimental design Suprafilt layout for 30m^3/h Master-slave amplifier system for fluidic oscillator

Chemical & Process Engineering ‘Engineering from Molecules’ Energetics: Power consumption Oscillatory flow draws less power than steady flow at the same throughput !

Chemical & Process Engineering ‘Engineering from Molecules’ With Oscillator Without Oscillator With Oscillator, Master (small) shut completely Visualization study and Frequency analysis

Chemical & Process Engineering ‘Engineering from Molecules’ Frequency of oscillation depends on feedback loop and air throughput

Chemical & Process Engineering ‘Engineering from Molecules’ Aeration: DO profiles, clear water Blow-up

Chemical & Process Engineering ‘Engineering from Molecules’ Delay time and dosage

Chemical & Process Engineering ‘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 & Process Engineering ‘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 & Process Engineering ‘Engineering from Molecules’ Microporous diffusers Fine mist of bubbles rising from Micropore Technologies Metallic membrane diffuser Median: 47 microns Standard deviation: 20 microns 20 micron sized pores

Chemical & Process Engineering ‘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 12m 2 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 Microporous diffuser Growing algae with microbubbles

Chemical & Process Engineering ‘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 & Process Engineering ‘Engineering from Molecules’ Ozone Kills! Ozone dissolves in water to produce hydroxyl 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 & Process Engineering ‘Engineering from Molecules’ Ozone plasma microreactor in the lab. Upper plate Lower plate Electrodes Electrical connection Fibre optics Chipholder construct

Chemical & Process Engineering ‘Engineering from Molecules’ Microfluidic onchip ozone generation Our new chip design and associated electronics produce ozone from O 2 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 & Process Engineering ‘Engineering from Molecules’ Plasma disks 25 plasma reactors each with treble throughput over first microchip

Chemical & Process Engineering ‘Engineering from Molecules’ Dosing lance prototypes Axial view of the old lance With 8 or 16 microdisc reactors New lance = 70 microdisc reactors Quartz for UV irradiation

Chemical & Process Engineering ‘Engineering from Molecules’ Corporation cock assembly Ball valve External assembly. Valve control to toggle for flow/no flow

Chemical & Process Engineering ‘Engineering from Molecules’

Chemical & Process Engineering ‘Engineering from Molecules’

Chemical & Process Engineering ‘Engineering from Molecules’

Chemical & Process Engineering ‘Engineering from Molecules’

Chemical & Process Engineering ‘Engineering from Molecules’ Dual ozone-UV prototype design New lance = 70 microdisc reactors Quartz for UV irradiation

Chemical & Process Engineering ‘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 & Process Engineering ‘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 & Process Engineering ‘Engineering from Molecules’ Construction Body / side view Top with lid Inner view: Heat transfer coils separating riser /downcomer. Folded perforated Plate  -bubble generator. Replaced by Suprafilt 9inch diffuser

Chemical & Process Engineering ‘Engineering from Molecules’ ALB for algae growth

Chemical & Process Engineering ‘Engineering from Molecules’ Results Rapid pH drop Potential licensee for carbon Sequestration organic chemistry 30% higher relative growth rate with only 60 minutes per day dosing TSB / Corus / Suprafilt project for continurous dosing. Best poster 6 th Annual bioProcessUK Conference, Nov 2009, York.

Chemical & Process Engineering ‘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 metre cube design with 0.8 m 2 square ceramic microporous diffusers.

Chemical & Process Engineering ‘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: CO 2 dosing and CO 2 /CH 4 stripping Accelerates biochemistry CHP provides CO 2 for algal growth Anammox process Stage 1 Aerobic (air dosing) Stage 2 Anaerobic CO 2 dosing and CO 2 /N 2 stripping Result: Accelerate biochemistry of all processes by reactive extraction. Influence production by nutrient dosing rate. Grow algae for biomass / biofuel. Sequester CO 2. Provide O 2.

Chemical & Process Engineering ‘Engineering from Molecules’ Potential microbubble markets Dispersed air flotation for solids removal in water and wastewater (achieved target bubble size, 20 microns) Wastewater aeration (partner YW, 18% energy reduction, 3-fold higher dosing rates on retrofit) Algal biomass / bioenergy production (partner Corus, >30% extra biomass from CO 2 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 & Process Engineering ‘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 and UoS KTA