In 2018, after five years of R&D, NXO developed the VOLTA sector (Valorization of wastewater via light energy and microalgae). A prototype of a new generation 100EH wastewater treatment plant (NXSTEP) based on patented micro-algal bio-remediation technology has emerged in Montpellier (France).


Why you need to contact us?

  • VOLTA, a positive energy station.
  • VOLTA, A carbon negative station
  • Two years of experience feedback


VOLTA, a positive energy station.

The sector has a double requirement: energy sobriety (0.12 kWh / m3 on VOLTA, a drop of 80% compared to the activated sludge sector) and autonomy via the production of renewable energy (methane).

VOLTA, A carbon negative station

The consumption of CO2 by the micro-algal pool during photosynthesis, the energy efficiency of the project and the absence of N2O (nitrous oxide) release induce a negative GHG impact.

The station does not use chemicals and does not generate organic waste.

Finally, keen to anticipate regulatory changes, NXO opted, from the design stage, for a “sensitive area” treatment target. Two years of experience feedback (CNRS monitoring) made it possible to ensure the effectiveness of the treatment.


This sector is based on the sizing and interaction of processes based on a consortium of microalgal catalysts and bacteria associated with anaerobic technologies. The whole constitutes a new model of urban wastewater treatment (ERU) allowing to considerably reduce the electricity consumption of the sector.

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