Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A Yeast Useful For Pollutant Removal Processes

28.06.2002


Sugar refineries and distilleries produce effluent which is harmful for the environment. The sugar industry produces two tonnes of sugar cane bagasse (a straw-like material) for every tonne of refined sugar. For Cuba this translates into 10 to 20 million tonnes of bagasse per year.



Distilleries, often associated with sugar cane production, emit copious amounts of polluting volatile components (especially volatile organic compounds, VOCs). In Cuba, an estimated annual 1 600 tonnes of ethanol, now the subject of control regulations, are released into the atmosphere. Stricter legislation recently introduced prompted many pieces of research to discover simple, cost-effective biological means of eliminating polluting elements from volatile emissions (biofiltration, biotrickling), which would be efficient enough to treat large volumes of even with low pollutant concentrations (about 1 g/m3).

A team from the IRD, in conjunction with the UAM (Mexico) and the ICIDCA (Cuba), has devised a laboratory-scale biofiltration system which can eliminate ethanol (along with smaller quantities of other possible VOCs ) emitted by distilleries, using sugar cane bagasse as support. The process involves passing the polluted air stream over a porous medium on which are fixed microorganisms preselected for their ability to decompose “target" compounds. Biofiltration is used successfully today at full industrial scale for controlling VOCs emissions from printing, certain branches of the food industry or for odour abatement at wastewater treatment plants.


The researchers first selected a yeast, Candida utilis, that could decompose ethanol, the organism’s only carbon source. Cultivation on a bed reactor followed, with the yeast growing directly on the bagasse which had been washed, sieved and sterilized. The bagasse is both solid and porous, allowing good circulation of polluted air, making it a good biofilter support. Inoculation with mineral salts, especially ammonium nitrate, helps increase the reactor’s degradation capacity. That salt brings nitrogen, which the yeast uses for increasing biomass and therefore for consuming more ethanol.

The team determined the optimal inlet ethanol concentrations needed to pass through the reactor for best biofilter efficiency. In suitable conditions, Candida utilis can rapidly decompose large quantities of ethanol. The yeast can thus eliminate up to 250 g of ethanol/hour/ m3 of the reactor. But any increase in ethanol loading rates must be gradual and doses of nutrient solution must be added stepwise. If the reactor is “overloaded” with ethanol, the yeast can no longer use, removal efficiency and elimination capacity drop abruptly and the system is blocked (1).

Candida utilis can be a prime remover simple molecules like ethanol from air. And a converter of waste into food, bagasse into balanced livestock feed. Its talent for harnessing the ethanol on bagasse and its naturally rich protein stock enables Candida utilis to enrich that material. The experiment achieved a 5.2 % protein concentration. Researchers are endeavouring to reach an even better figure. Whether or not the animals will accept this new forage remains to be confirmed. Indications are that they do, judging by trials under way in Cuba.

Ethanol biofiltration by Candida utilis has still to be investigated at larger scale and then at full industrial proportions. If successful, the process could be applied in other tropical countries which are major producers of sugar and alcohol, like Brazil, Cuba, Mexico and India.

(1) Yeast oxidizes ethanol, but not completely, converting it first into acetaldehyde, then acetic acid..

Marie-Lise Sabrie | alfa

More articles from Agricultural and Forestry Science:

nachricht Back to Nature: Palm oil plantations are being turned back into protected rainforest
21.03.2019 | Forschungsverbund Berlin e.V.

nachricht The inner struggle of the evening primrose: Chloroplasts are caught up in an evolutionary arms race
14.03.2019 | Max-Planck-Institut für Molekulare Pflanzenphysiologie

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Quantum gas turns supersolid

Researchers led by Francesca Ferlaino from the University of Innsbruck and the Austrian Academy of Sciences report in Physical Review X on the observation of supersolid behavior in dipolar quantum gases of erbium and dysprosium. In the dysprosium gas these properties are unprecedentedly long-lived. This sets the stage for future investigations into the nature of this exotic phase of matter.

Supersolidity is a paradoxical state where the matter is both crystallized and superfluid. Predicted 50 years ago, such a counter-intuitive phase, featuring...

Im Focus: Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

A stellar flare 10 times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter

  • Coolest and smallest star to produce a superflare found
  • Star is a tenth of the radius of our Sun
  • Researchers led by University of Warwick could only see...

Im Focus: Quantum simulation more stable than expected

A localization phenomenon boosts the accuracy of solving quantum many-body problems with quantum computers which are otherwise challenging for conventional computers. This brings such digital quantum simulation within reach on quantum devices available today.

Quantum computers promise to solve certain computational problems exponentially faster than any classical machine. “A particularly promising application is the...

Im Focus: Largest, fastest array of microscopic 'traffic cops' for optical communications

The technology could revolutionize how information travels through data centers and artificial intelligence networks

Engineers at the University of California, Berkeley have built a new photonic switch that can control the direction of light passing through optical fibers...

Im Focus: A long-distance relationship in femtoseconds

Physicists observe how electron-hole pairs drift apart at ultrafast speed, but still remain strongly bound.

Modern electronics relies on ultrafast charge motion on ever shorter length scales. Physicists from Regensburg and Gothenburg have now succeeded in resolving a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

Fraunhofer FHR at the IEEE Radar Conference 2019 in Boston, USA

09.04.2019 | Event News

 
Latest News

Marine Skin dives deeper for better monitoring

23.04.2019 | Information Technology

Geomagnetic jerks finally reproduced and explained

23.04.2019 | Earth Sciences

Overlooked molecular machine in cell nucleus may hold key to treating aggressive leukemia

23.04.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>