| Abstract: | The Canadian “Couplan Process” uses the absorptive capacity of sphagnum (peat) moss to remove heavy metal contaminants from aqueous effluents. Disposal of the peat moss is accomplished through incineration, which then permits metal recovery. Wet air oxidation (WAO) is a possible alternative to incineration for reducing the volume of peat moss wastes and recovering the metal. The objective of this study was to assess the feasibility of WAO for recovering mercury from pcat moss. Studies were performed by preparing samples of peat moss slurrics (up to 25% water added to air-dried peat moss) and exposing them for two hours to stoichiometric excess oxygen in a stirred autoclave at temperatures reaching 500°F. Mercury-free samples were studied, as well as those containing 3% by weight of HgS to simulate the saturated moss. The reduction in solids volume was almost 100%; about 5% by weight of the original peat moss was converted to acetic acid; ash residues amounted to 3 to 4% of the initial peat moss, and consisted of about 50% mercury by weight; about 2% of the original mercury was present in the final solution. It was concluded that wet air oxidation represents a possible alternative to incineration in the Couplan process. |
