Browse Publications Technical Papers 2001-01-2196

Electrical Impedance Spectroscopy for On-Line Estimation of Viable Biomass 2001-01-2196

Electrical Impedance Spectroscopy (EIS) consists on the measurement of electrical impedance at different frequencies. The electrical impedance of a biological sample has a specific behaviour with respect to the frequency of the electrical current injected. This behaviour can be distinguished from that of a sample without cells or with dead cells. NTE started the development of this technology in the frame of a project of the European Space Agency (1) and in collaboration with the UPC.
This technology has started a technology transfer process, in which three companies from three different fields: a brewery (Freixenet, S.A.), a water treatment plant engineering company (Indeco, S.A.) and a pharmaceutical company (Biokit, S.A.) have evaluated the technology for their production requirements.
Specifications were issued for each process considered in case:
  • On-line viable yeast cell determination in CAVA production line.
  • Determination of viable biomass in activated sludge in the biological reactor of a water treatment plant.
  • Determination of Eschericia coli concentration in a protein production process.
NTE designed a system for each case with specific electrodes, electronics and software. These systems were tested at each company in each industrial process. Requirements on Biomass determination in threshold, resolution, repeatability and accuracy were set. The tests have shown compliance of the systems with the requirements.
The following results were obtained for each application:
  • On-line viable yeast cell determination. The technology is able to measure on-line the amount of viable yeast in the fermentation tanks and monitor the whole growth process.
  • Determination of viable biomass in activated sludge. The technology is able to provide the biomass concentration from low concentration values and to give an estimation on the distribution of the population in the activated sludge (from bacterial to algae)
  • Determination of Eschericia coli concentration. The technology is able to monitor on-line the viable biomass during growth process in a bioreactor.


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