Abstract: Floride and aluminum values, as well as carbon, are recovered from waste cathode liner material from aluminum electrolytic cells by leaching of the liner at ambient temperature with a caustic solution, followed by precipitation of sodium fluoride by saturating the leach liquor with a compound which suppresses the solubility of sodium fluoride in the leach liquor. Ammonia is a preferred compound. Aluminum compounds, as well as the carbon values, are also recovered. Treating chemicals used in the process are recycled. The process is essentially a closed-cycle process with substantially no discharge of effluent.

Abstract: Alternate hydrophilic and hydrophobic fiber filters are used to remove particulate matter and oil from aqueous animal processing wastes, such as those from cannery operations, poultry processing plants and packing plants. The fiber used to make the filters is preferably a low-lignin content, cellulosic fiber that is digestible by ruminating animals. The adsorbed oil in the hydrophobic filter may be removed and the filter reused. The hydrophilic fiber filter containing particulate matter may be dewatered and converted to animal feed or fertilizer.