Abstract: The invention concerns a method for stabilizing and conditioning wastewater sludge. The invention is characterized in that it consists in treating sludge in an acid environment (3.0?pH?5.0), with an inorganic acid and two oxidizing agents, that is a ferric iron salt and hydrogen peroxide. The ferric iron salt is used in such an amount as to obtain a concentration ranging between 5 and 40 kg of Fe per iron of dry sludge; the hydrogen peroxide is used in such an amount as to obtain a concentration ranging between 5 and 40 kg of H2O2 per ton of dry sludge; mixing the treated sludge for a time interval sufficient to stabilize the sludge and improve its dehydrability; then flocculating the stabilized sludge by adding an organic polymer; then dehydrating the flocculated sludge. Said method enables to significantly improve the dehydrability properties of the sludge while increasing the dry solid content during its mechanical dehydration.

Abstract: The invention relates to a hybrid biological and chemical method for decontaminating sludge containing heavy metals and pathogenic microorganisms, consisting of the following steps: the sludge is mixed with an acidic leaching solution in order to acidify the sludge with a pH which is low enough to solubilize the majority of the heavy metals and to destroy most of the pathogenic microorganisms but which is also high enough to minimize the solubilization of fertilizing elements; oxidation-reduction of more than +400 mv is maintained, liquid-solid separation occurs in order to obtain a solid fraction comprising decontaminated acidic sludge and a liquid fraction comprising heavy metals which are dissolved in a leaching solution; the sludge is neutralized: and neturalized decontaminated sludge is recovered, whereby the fertilizing elements contained therein, i.e. carbon, nitrogen and phosphorus, remain substantially unchanged in relation to the initially contaminated sludge.

Abstract: A method of treating animal manure yielding a final liquid fraction and solid fractions whereby the final liquid fraction has a suspended solids (SS) content of about 3 g/L or lower comprising subjecting at least a part of said manure to a first biological passive flotation step in a flotation unit having a hydraulic residency time (HRT) of about 4 to about 24 hours with a polymer to yield a first flotation solid fraction and a first flotation liquid fraction, said method comprising a further treatment.

Abstract: The invention relates to a hybrid biological and chemical method for decontaminating sludge containing heavy metals and pathogenic microorganisms, consisting of the following steps: the sludge is mixed with an acidic leaching solution in order to acidify the sludge with a pH which is low enough to solubilize the majority of the heavy metals and to destroy most of the pathogenic microorganisms but which is also high enough to minimize the solubilization of fertilizing elements; oxidation-reduction of more than +400 mv is maintained, liquid-solid separation occurs in order to obtain a solid fraction comprising decontaminated acidic sludge and a liquid fraction comprising heavy metals which are dissolved in a leaching solution; the sludge is neutralized: and neturalized decontaminated sludge is recovered, whereby the fertilizing elements contained therein, i.e. carbon, nitrogen and phosphorus, remain substantially unchanged in relation to the initially contaminated sludge.

Abstract: The present invention relates to a semi-continuous process for removing heavy metals, substantially reducing volatile suspended solids and substantially destroying indicator bacteria from municipal sludges, which comprises: a) adding 1 to 3 g of sulphur per liter to a volume of municipal sludge and allowing the sulphur oxidizing thiobacilli initially present in said sludge to proliferate under aerobic conditions in said sludge being agitated until the pH of said sludge is lowered to about 1.5 to 2.