Patent FR-2939425-A1 (FR)
Title: Decontamination of wastewater discharged in a basin of sewage plant and containing harmful cationic metals and organic pollutants, comprises introducing polysaccharide sodium alginate in the basin, and complexing metal cations in the basin
Inventor: ROBERT JEAN PHILIPPE
IPC: C02F9/04
Filed: 2008-12-08
Abstract: The process comprises introducing polysaccharide sodium alginate derived from alginic acid having a high proportion of L-guluronic acid blocks of fixed percentage in the basin for diluting the waste water, complexing metal cations in the basin with alginate ions, and mechanically collecting chelates (26) or macromolecules suspended in water to obtain purified water. Each cation forms a covalent bond with an anionic oxygen radical of a polysaccharide alginate monomer. Each divalent cation forms two covalent bonds with two oxygen radicals of two monomers such as G alginates. The process comprises introducing polysaccharide sodium alginate derived from alginic acid having a high proportion of L-guluronic acid blocks of fixed percentage in the basin for diluting the waste water, complexing metal cations in the basin with alginate ions, and mechanically collecting chelates (26) or macromolecules suspended in water to obtain purified water. Each cation forms a covalent bond with an anionic oxygen radical of a polysaccharide alginate monomer. Each divalent cation forms two covalent bonds with two oxygen radicals of two monomers such as G alginates of two different polysaccharides of alginate for naturally forming a chelate or insoluble macromolecule, which is constituted of a three-dimensional structure of polymers constituted of polysaccharides bridged by divalent cations between which the organic pollutants are physically sequestered. The chelates are collected from the surface of the basin water using a scraping device. The collected chelates are subjected to an ion reversibility reaction to form sludge containing cationic metals separated from alginate monomers, alginate, water and organic pollutants released by the ion reversibility reaction. The collected chelates are mixed with a fixed agent causing the ion reversibility reaction during the separation step. The determined agent is constituted of a potassium, magnesium and/or saturated sodium solution and sodium chloride solution. The sludge containing cationic metals is dried, burned and then released during the separation for extracting the water by evaporation to obtain maximum dryness of the sludge. The process further comprises degreasing wastewater from a feeding channel, cleaning and screening during which separating sand, mud, gravel and ash from waste water, sedimenting by agglomerating suspended solids in sub-steps of coagulation and flocculation or flotation during which injecting pressurized air into the waste water to move the solids to the surface and then extracting, biologically treating the waste water, cleaning the treated water, and releasing the treated water in a natural medium. The polluted water is modified by immersing a flow of waste water in a porous container containing a specific quantity of alginate. The specified percentage of sodium alginate introduced in the diluted wastewater is proportional to the concentration of metals contained in the wastewater. An independent claim is included for an arrangement for decontamination of wastewater discharged in a basin of a sewage plant.