Abstract: The invention relates to a process for the stabilization of sludge or other waste with a high organic matter content derived from treatment operations of industrial and/or urban effluent, or from drinking water treatment operations of surface or ground water, said sludge containing at least one part dry matter essentially made up of fermentable organic matter, characterized in that it is conducted at ambient temperature and atmospheric pressure, and in that it comprises a stage consisting of acidifying said sludge with at least one strong acid to a pH of between 1.5 and 3.5, a stage consisting of adding at least one nitrite salt to said sludge at a concentration of between 10 and 500 mg N.NO.sub.2 /l sludge, and in that it consists of maintaining the mixture made up of said sludge, said acid and said nitrite salt in contact for a period of between 5 minutes and 12 hours, under permanent or intermittent mixing.

Abstract: A method for the purification and biodeodorizing of a gas effluent charged with pollutant matter is provided. The method includes the steps of passing the gas effluent through a bed of inert granular material used as a support for a biomass. The biomass includes bacteria, majority of which are autotrophic bacteria. Preferably the bacteria are in a form designed to degrade the pollutant material. The method includes the step of sprinkling the bed with a sprinkling liquid and recovering purified biodeodorized gas effluent. Preferably, nutrient elements for the biomass are supplied entirely by the sprinkling liquid, the gas effluent or a mixture thereof.