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This study investigated theconventional physico-chemical treatment technologies for removing aluminum, arsenic,copper, mercury, and selenium from a highly acidic (pH 2.7) groundwater which wascontaminated due to the past industrial activities. A bench-scale study was conductedto test pH adjustment technologies and metal removal processes. The processesinvestigated include chemical coagulation/flocculation followed by sedimentation, dualmedia (sand/anthracite) filtration, and granular activated carbon (GAC) adsorption. Limeand caustic soda were used for pH alteration. Alum and Iron coagulants were jar testedfor their effectiveness in metal removals at different dosages and pH range. The testdata indicates that lime addition is not only effective in pH adjustment but also inprecipitating out almost all the target metals. Caustic soda is shown to be as effective aslime for pH adjustment. However, caustic soda's cost and handling will be higher. Inaddition, lime provided an added benefit of imparting alkalinity. The jar test result showedthat both Iron and Alum coagulants are effective in metal removals. However, forselenium removal further investigation is recommended. It was also found that chemicalcoagulation/flocculation/sedimentation process alone is sufficient to reduce almost allthe target metals to the required effluent limits. The additional treatment processes,dual filtration and adsorption, may not be needed for polishing the effluent. The existingwater treatment plant practices at the industrial facility were looked into and somerecommendations were made for better and effective operation. Installation of a limedose monitoring equipment and a proper settling tank with sludge removal mechanismmay be considered. Includes 2 references, tables, figures.

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Edition: Vol. - No. Published: 11/15/2004 Number of Pages: 9File Size: 1 file , 320 KB