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Thermally assisted mechanical dewatering process


Key words Thermally assisted, dewatering, low pressure, pre-treatment, biomass, pressing
Latest version 2013/09/05
Completed by INRA - IATE

How does it work?

Primary objective dewatering process with improved efficiency (higher yield rate, lower energy consumption)
Working principle This process is an alternative solution to conventional pressing processes, and as such, is designed to be a pre-treatment prior to a thermal dryer.

Basically it is an improved filtration (2). This relatively soft method is characterized by a first key stage at low pressure and with a heating temperature (3) lower than the evaporation temperature of the liquid to be eliminated (4). The product to be dehydrated is introduced into a device of filtration and/or compression and is adequately heated (2,4).

In the case of Alfalfa (Medicago sativa), this process allows to reach an intermediary dry solid content of 62.5%, instead of 32.5% with the conventional pressing processes. (1)

Additional effects Mass gain of green juice - charged in nitrogen, pigments and other molecules that may be valued - is more than 75 % and the quantity of water to be evaporated is approximately divided by 4 (these results are for dewatering + thermal dryer).

The coupling between this process of dewatering and thermal drying allows energy savings of at least 30 % compared to conventional pressing + thermal drying processes. (1)

Important process parameters - pressure: lower than 700 kPa

- temperature: lower than the evaporation temperature of the liquid to be eliminated

Important product parameters moist products

What can it be used for?

Products Wet biomass, including Alfalfa, which is used as feed, and also liquid or pasty waste such as paper sludge or worn sodium bentonite.

To be tested on other wet materials.

Operations separation
Solutions for short comings Improved mass gain of green juice

alternative solution to conventional pressing processes

optimized energy balance, energy saving

What can it NOT be used for?

Products dry products
Operations Any other than separation
Other limitations not known
Risks or hazards not known


Maturity The method is patented for France with international extension, and licenses are available through INRA Transfert

For the moment no implementation is known.

Modularity /Implementation This technology could replace the existing dewatering device in the production line, yet the scale up has to be performed.
Consumer aspects not known
Legal aspects The technology is patented for France with international extension: FR2923587, PCT WO2009/095556 (2007)
Environmental aspects Reduced energy consumption compared to conventional pressing processes

Further Information

Institutes ENSTIMAC
Companies INRA Transfert
References 1. Fernandez M.A., Auduc B., Arlabosse P., and Mahmoud A. 2009. Method for mechanical dehydration with thermal assistance. WO2009095556 FR2923587, EP2212637

2. Saalasti T. 2000. Method and a device for improving liquid removal. US6076279

3. Steinemann Geb H. 2000. Water removal from contaminated residues in concrete pans heated at the base and covered by a semipermeable membrane. DE19860181

4. Mahmoud A., Fernandez A., Chituchi T.M., and Arlabosse P. 2008. Thermally assisted mechanical dewatering (TAMD) of suspensions of fine particles: analysis of the influence of the operating conditions using the response surface methodology. Chemosphere Aug;72(11):1765-73.

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Created by Hte inra on 4 December 2012, at 15:05