| 摘要 |
A PROCESS AND SYSTEM FOR REMOVING HEAVY METALS, FLUORIDE,SILICA AND OTHER CONTAMINANTS FROM LARGE VOLUMES OF WASTEWATER IS DISCLOSED. IN THE PROCESS, A WASTEWATER STREAM CONTAINING THE CONTAMINANT IS TREATED WITH A CHEMICAL COAGULANT TO CREATE A PARTICLE HAVING A DIAMETER GREATER THAN 5 MICRONS. TREATED WASTEWATER IS PASSED THROUGH A MICROFILTRATION MEMBRANCE WHICH PHYSICALLY SEPARATES THE METAL CONTAMINANT PARTICLE FROM THE WASTEWATER. COMMERCIALLY AVAILABLE MICROFILTRATION MEMBRANES HAVING A PORE SIZE FROM 0.5 MICRON TO 5 MICRONS MAY BE USED. THE TREATED WASTEWATER FLOW RATE THROUGH THE MICROFILTRATION MEMBRANES CAN RANGE FROM 700 GALLONS PER SQUARE FOOT OF MEMBRANE PER DAY ("GFD" ) TO 1500 GFD FOR METAL CONTAMINANTS AND FROM 150 GFD TO 600 GFD FOR SILICA CONTAMINANTS. SOLIDS ARE REMOVED FROM THE MEMBRANE SURFACE BY PERIODICALLY BACKFLUSHING THE MICROFIL-TRATION MEMBRANES AND DRAINING THE FILTRATION VESSEL WITHIN WHICH THE FILTRATION VESSEL IS FLUSHED INTO A HOLDING TANK FOR FURTHER PROCESSING OF THE SOLIDS.
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