A system for recovering fat, oil and grease (FOG) from wastewater has multiple annular flotation zones in a concentric configuration surrounding a central column to create progressively increasing surface areas for FOG and solid particles flotation. Each flotation zone may be equipped with an independent pressurized micro air and/or ozone bubbles distribution system. The FOG is recovered in the first flotation zone without chemical additions. Coagulant and flocculant may be added in the second flotation zone to maximize removals of biochemical oxygen demand (BOD), total suspended solids (TSS), and colloidal particulates and produce clear effluent. Magnesium chloride is added in the third flotation zone to remove phosphorus and to form struvite particulates that can be used as fertilizer. Since both organic loading and solid loading in the treated effluent are significantly reduced, poultry processing plants can more easily meet wastewater treatment plant discharge limits and avoid surcharges.
