Microbubbles win awards!

2010 Microbubble innovation wins AXA Insurance Cleantech Open UK ideas competition

UK CleanTech Open Press Release

Scunthorpe local news

2010 Royal Society Innovation Award (Brian Mercer Fund)

Read the stories below:


The Royal Society has released the video http://royalsociety.org/Brian-Mercer-Awards-for-Innovation/
The direct link is http://www.youtube.com/watch?v=ZGhODZev7lo

2009 Institution of Chemical Engineers Moulton Medal

The Institution of Chemical Engineers have recently selected a journal article, authored by five current and previous members of the Department of Chemical and Process Engineering at the University of Sheffield, for the Moulton Medal for 2009. The award recognizes the best paper published in all the Institutions journals for the year.

The award letter can be view here:MoultonMedal Letter.

The paper is about the design of an air-lift loop bioreactor which exploits a recent patent by two of the co-authors [Zimmerman and Tesar, WO2008053174, http://www.wipo.int/pctdb/en/wo.jsp?WO=2008053174] for the energy-efficient generation of microbubbles. The team has shown up to 18% less energy consumption for microbubble production over the typical fine bubbles of 1-3mm diameter and estimates of 50-fold greater mass transfer rates for its 20micron size bubbles produced from a 20micron pore size microporous diffuser (see figure below, right hand side).

Comparison of large bubbles (without fluidic oscillator) and microbubbles with.

W B. Zimmerman, B N. Hewakandamby,V Tesař, H.C. H. Bandulasena, O A. Omotowa, On the design and simulation of an airlift loop bioreactor with microbubble generation by fluidic oscillation Food and Bioproducts Processing 87: 215–227, 2009.

Because the microbubbles are so small and rise slowly and smoothly, they do not naturally generate as much overall stirring effects as the large bubbles in the Figure above on the left, even though they dissolve the gas at a much higher rate. The air-lift loop design manages to corral the strong momentum transfer effects by creating a global stirring motion for rapid overall mixing. See the figure below left.

Schematic of the air lift loop bioreactor Artist's impression of the airlift loop bioreactor with fluidic oscillator

The article is solely about the design of the novel microbubble generation within an air-lift loop bioreactor.
So how well does it work?

The preliminary answer to this question is with algal growth.
At the 6th Annual bioProcessUK conference in York, November 2009, the poster of James Hanotu
(co-authored by Dr Jim Gilmour of MBB and Prof Will Zimmerman of CPE) was awarded the Best Poster certificate
by the 200+ delegates at the conference for his poster entitled which can be viewed here: Bioculture Growth Enhancement Mediated by CO2 Enriched Microbubbles

The major conclusions of the poster are that from the air-lift loop bioreactior performance,
Microbubbles dissolve CO2 faster and therefore increase algal growth (see figure below). This may be useful in many carbon sequestration processes.
Algal culture with the fluidic oscillator generated bubbles had ~30% higher yield than conventionally produced bubbles with only dosing of one hour per day over a two week trial period.
Bioenergy could become a more attractive option in the recycling of the high concentration of CO2 emissions from stack gases.

pH drops off a cliff with microbubble dissolution of CO2

Update on Steel Plant Stack Gas Trials (publication deadline 31 October 2010). Without prejudicing the peer review process, we will post a preprint of the journal article when it is submitted for publication.

Two views of the ALB in phase I and II trials at TataSteel

Growth curve that shows the effect of stripping oxygen from our pilot scale algal bioreactor.
Trial 1 was limited by technical issues to 2-4 hours dosing per day with CO2, and the liquid temperature was chilly 14C, rather than trial 2 at 10-12 hours dosing per day and 23 C. Trial 1 was a "success" because we stripped all the O2 and had 100% survival rate. Trial 2 was a better test, and still had the 100% survival rate and stripped all the O2. 40-fold increase is not too bad (see) below.

Neither trial had been conducted in the case presented for the Royal Society, made in March The gas analysis of inlet and outlet streams to the reactor shows that we sank >30% of the CO2 in a 40 liter / min stack gas stream).

The consensus among plant scientists I spoke to before our feasibility studies was that the steel processing stack gas would probably kill the algae.

Relative growth curves for the two trials

The exponential growth curve is fully consistent with the lack of oxygen inhibition.
No, the left figure is not an advertisement for white transit vans: the bioreactor is dark enough with algal density that it reflects the parked van with the mobile gas analysis units!

Check out these two journal article preprints:
Towards energy efficient nanobubble generation with fluidic oscillation


Pilot scales studies of microbubble mediated airlift loop bioreactor growth of a microalgae Dunaliella salina.


hese preliminary laboratory experiments form the basis of a field trial being developed with funding from the Technology Strategy Board for
testing the continuous dosing of the bioreactor with CO2 rich stack gas from industrial processes: see

Steel plant CO2 sequestration using high efficiency micro-algal bioreactor

PRESS CLIPPINGS (google: microbubbles + biofuels!)

Read the University of Sheffield press release 7 January 2010: Scientists breakthrough in production of biofuels

Read the personal story: Warren County Native wins science award.

Read the trade article in February 2010 edition of Chemical Engineering: Microbubble generator enhances performance of airlift reactor.

Read the trade article in March 2010 edition of Chemical Processing: Small bubbles offer big benefits.

Read the feature article in 23 February 2010 release of Materials Today: Microbubbles take first prize

Read the feature article in 8 March 2010 release of The Engineer: Bursting with Energy.

as well as 1 February 2011: Microbubbles method benefits biofuel production

Catch the 4 February broadcast of BBC Radio 4 Material World with Quentin Cooper: Quentin Cooper finds out how microscopic bubbles could boost biofuel production.

The IChemE and Elsevier hosted a webinar on 14 July 2010 to celebrate the Moulton Medal. Webinar link Slides only

You can find several preprints / reprints in http://eyrie.shef.ac.uk/steelCO2/open

Please contact w.zimmerman@shef.ac.uk for any corrections to the web site
16 October 2010.

This site has been hit: http://counter.digits.com/wc/-d/4/mech2k2times since 01/11/2001
Webcounter courtesy of: