A stabilization process of Thickened Sludge

Thickened sludge are put in an acid reactor (pH between 2 and 3). During 30 minutes, sludge are in contact with nitrite ions (NO2-) powerful reagent in acid condition to destroy the reduced "osmophore components" (H2S, mercaptans), responsible of bad odors, and to inactivate the germ achieving the organic matters removal.

This process is similar to a stabilization phase, and according to the pH of the reaction, this stabilization meets the hygienisation standard of either Class A EPA (pH around 2) or Class B EPA (pH around 3). Therefore the sludge can be stored during several months without odors. In the reactor, the amount of nitrite injected is controlled by checking the pH level.

• Competitive cost compared to the other stabilization methods,
• Liquid sludge can be treated
• Compared to the "lime stabilization", the effluent could be treated after the Saphyr (incineration)
• Low footprint
• Increase the nitrogen concentration in the sludge,
  
  - Increase the concentration of heavy metals in the liquid phase, the quality of the dewatered sludge is increased.