METHOD OF TREATING WASTE WATERS CONTAINING PETROLEUM AND/OR PETROLEUM PRODUCTS WITH REUSING TREATMENT PRODUCTS Russian patent published in 2000 - IPC

FIELD: oil pollution removal. SUBSTANCE: waste water is passed through sand catchers, oil removers, repeat settling tanks, and flotation installations wherein a part of sand and up to 95% of oil are separated, oil being then returned into main process to be subjected to electrical desalting and dehydration in electrical dehydrators and/or to atmospheric vacuum distillation. Sludge is processed after heating in steam heaters, into which part of steam is directly injected and simultaneously subjected to pump- mediated circulation to impart homogeneity to sludge-steam mixture. Thus treated sludge is pumped into decanter and then subjected to mechanical centrifugal density separation into oil, aqueous, and solid phases. When settled, oil phase is returned into stock tanks of petroleum- processing enterprise. Aqueous and solid phases are removed separately. Novelty consists in that heating steam utilized in at least a part of heating processes is steam produced in steam generators by burning associated gas and/or process gas released in thermal-destruction processes proceeding in processing of petroleum and/or intermediate products, and/or released in processing of petroleum recovered from petroleum- containing sediments: waste water treatment products, associated or process gas being fed into fuel system at temperature chiefly 50-70 C and pressure chiefly 3-5 kg/sq.cm. Prior to be burned, gas is preheated to at least 100 C. Advantageously, 15-40% of gas is burned in steam generator and 60-85% in process installations. As water, return condensate with chemically purified fresh water added is used in amounts at least sufficient to replace lost condensate. To heat chemically purified fresh water and/or initial petroleum, residual heat of spent steam and/or steam condensate from petroleum distillation processes is utilized. EFFECT: improved waste water purification and increased oil recovery; reduced external water and external steam consumption; and reduced amount of gas uselessly burned out in torch. 22 cl, 1 tbl