REMOVAL OF TRACE MERCURY(II) FROM DRINKING-WATER - SORPTION BY GRANULAR ACTIVATED CARBON

Optimum conditions were established for abstracting mu-g/L levels of Hg(II) species from aqueous solution and drinking water using the FS-400 granular activated carbon (GAC) as adsorbent. The conditions were: system pH around 7, GAC suspension density of greater-than-or-equal-to 100 mg/L, and a mixing or contact time of 1 h. Uptake of Hg(II) increased in the presence of 1-10 mg/L of humic acid, nitrilotriacetic acid (NTA) or Fe(III) salts; was little affected by Al(III) salts; and decreased when Ca(II) and Mg(II) levels exceeded 50 mg/L. The amount of Hg(II) adsorbed per unit weight of GAC varied with the initial concentration of Hg(II) until saturation was achieved. Under optimum conditions, the residual Hg(II) levels were below the maximum acceptable concentration (MAC) values given in the Guidelines for Canadian Drinking Quality.