EMULSION LIQUID MEMBRANE EXTRACTION OF SELENIUM FROM REFINERY WASTE WASTE WATERS

SELENIUM IS PRESENTLY THE PRIMARY WASTEWATER TREATMENT CHALLENGE FOR MANY WEST COAST PETROLEUM REFINERIES, AND SELENIUM IS ALSO PRESENT IN SIGNIFICANT QUANTITIES IN WASTEWATERS FROM COAL-FIRED POWER PLANTS. A SUSPECTED CARCINOGEN, SELENIUM IS ALSO HARMFUL TO FISH AND FOWL WHEN PRESENT IN SURFACE WATERS. PROCESSES DEVELOPED FOR SELENIUM REMOVAL FROM DRINKING WATER (ANION EXCHANGE AND ACTIVATED ALUMINA) HAVE TECHNICAL LIMITATIONS WHICH MAKE THEM TOO EXPENSIVE FOR THE TREATMENT OF INDUSTRIAL WASTEWATERS. IN PARTICULAR, THESE PROCESSES ARE APPROPRIATE FOR SMALL VOLUMES OF WATER WITH LOW LEVELS OF DISSOLVED AND SUSPENDED SOLIDS. FOR THESE PROCESSES TO ACHIEVE HIGH REMOVAL EFFICIENCIES, THE SELENIUM MUST BE PRESENT AS ONLY ONE ANIONIC SPECIES, AND COMPETING ANIONS LIKE SULFATE OR CARBONATE MUST NOT BE PRESENT. THEREFORE, TDA RESEARCH PROPOSES USING EMULSION LIQUID MEMBRANES (ELM) TO REMOVE SELENIUM FROM INDUSTRIAL WASTEWATER STREAMS. BASED ON THEIR PREVIUS RESEARCH WITH CHROMIUM (VI) CONTAMINATED WATER, TDA EXPECTS ELM TO CONCENTRATE SELENIUM BY A FACTOR OF APPROXIMATELY 1000. IN PHASE I, THEY WILL CONDUCT EXPERIMENTS TO DEMONSTRATE PROCESS FEASIBILITY, AND CARRY OUT ECONOMIC ANALYSES TO COMPARE THEIR ELM PROCESS WITH OTHER COMPETING SELENIUM CONCENTRATION AND/OR REMOVAL PROCESSES.