The device belongs to biotechnology and bioenergy and can be used for obtaining electrical energy with the help of microorganisms in microbial fuels elements in wastewater treatment processes. The device consists of anode and cathode chambers and ion exchange membrane, and additionally in the anode chamber a block with fibrous cells is placed carriers on which an association of anaerobic organic-destroying bacteria is immobilized substances Association of anaerobic bacteria-destructors of organic substances beforehand build up in an anaerobic reactor during the treatment of wastewater with high concentrations organic substances. Technical result: increasing the efficiency of the acquisition process of electricity up to 30%.