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U.S. Department of Energy
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Process for treating aqueous effluents

Patent ·
OSTI ID:6081901
An improved process for the treatment of aqueous effluents containing strong anions such as sulphate, nitrate, chlorides and fluorides wherein the aqueous effluent is subjected to a biological purification process is described. According to the process, aqueous effluent such as those obtained by condensation of gases present in a coal gasification plant and containing these anions and others in a combined concentration of at least 2 mval/1 and organic contaminants in a concentration of at least 1000 mg/1 are subjected to the biological purification followed by separation of water from solids of the effluent. Thereafter, the water is subjected to anion exchange in an anion exchanger against hydrogen carbonate ions and at least part of the so-treated water is recycled to the aqueous effluent so as to be present therewith during the biological purification. By such a process the biological purification can be conducted at an optimum pH such as a pH in the range of 6 to 8. CO/sub 3//HCO/sub 3/ ions contained in the water from the anion exchanger can be concentrated by passing the water through a cooling tower whereby a portion of the same is evaporated.
Assignee:
Metallgesellschaft AG (Germany, Federal Republic of); Sasol One (Proprietary) Limited (Germany, Federal Republic of)
Patent Number(s):
US 4483772
OSTI ID:
6081901
Country of Publication:
United States
Language:
English

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