METHOD FOR CLEANING DISCHARGE FLUIDS FROM PHOSPHATES AND SULPHATES Russian patent published in 2016 - IPC C02F9/04 C02F1/58 C02F101/10 C02F103/28 C02F103/32 

FIELD: treatment plants.

SUBSTANCE: present invention can be used for purification of urban waste water, as well as for purification of waste water from food and pulp and paper industry from sulphate and phosphate. Waste water after biological treatment go to cleaning stage I where water is treated with chlorine iron FeCl₃·6H₂O, it is followed by deposition of phosphates in the form of hardly soluble salt of iron phosphate FePO₄ and separation of residue. Chloric iron is added with a small excess while intensively mixing with air. During stage II after acidification of waste fluid with hydrochloric acid to pH = 4 barium chloride BaCl₂·2H₂O is introduced in the amount of 130-640 mg/l at the initial concentration of sulphates of 150-350 mg/l and the sulphates are deposited in the form of hardly soluble salt barium sulphate BaSO_4. Process of depositing barium sulphate crystals is accelerated by feeding excessive active sludge from the biological treatment facility in the amount of 100-300 mg/l. Residue from the settlers of stages I and II is directed to filter-presses, the dewatered sediment is transported to SDW landfill (solid domestic waste), and the filtrate with the smallest crystals BaSO₄ is returned to the sedimentation chamber of stage II.

EFFECT: invention provides higher degree of removal of sulphates and phosphates, reduced volume of sediment, reduced time of settling, reduced operating costs.

1 cl, 2 tbl, 1 dwg