The technical and economic feasibility of the separation of organic materials and other contaminants from primary and secondary sewage effluent by a foam fractionation-flotation process was studied. Air-waste water mixtures were held at pressures above 150 psi for from 6 to 25 minutes and then bled to a release vessel where pressures were reduced to atmospheric. Soluble organic and particulate matter collected at the bubble-water interfaces of the fine bubbles being evolved from the supersaturated liquid. Effects of varying flow rate, pressure, contact time, and of different release vessels and additives were studied. 70%, 90%, and 40-80% reductions of COD, phosphates, and suspended solids were effected at optimum conditions of air-to-water volume ratios of 2.17 to 1, pressures greater than 175 psi, and with 300-400 mg/l alum or ferric chloride as coagulants. Estimated costs, exclusive of chemicals were 5 cents/1000 gallons for a 10 mgd plant. (WRSIC abstract)