Cell Immobilized FOG-Trap System for Fat, Oil, and Grease Removal from Restaurant Wastewater

Cell immobilized lipase-producing bacteria on three different matrices were incorporated in a fat-, oil-, and grease (FOG) trap system for restaurant wastewater treatment. During a 16-day laboratory-scale experiment for the treatment of synthetic FOG wastewater containing soybean oil, no significant difference (two-tailed t test at 95% confidence interval) in the FOG removal between two systems was observed at FOG influent ≤ 1,000?mg/L. However, the typical trap showed lower FOG removal efficiency than the matrix-based system when the influent FOG concentration was increased to ≥ 5,000?mg/L. In addition, the matrix-based trap system was able to sustain a stable high FOG removal, with <100?mg/L effluent, even at 10,000 mg/L influent FOG. Based on FOG heights measured and mass balance calculations, 97.4 and 99.5% of the total FOG load for 16 days were removed in a typical trap and matrix-based system, respectively. About 93.6% of the removal in the matrix-based was accounted to biodegradation. The 30-day full-scale operations demonstrated a distinguishably better performance in the matrix-based system (92.7±9.06% of 1,044.8±537.27?mg FOG/L) than in the typical trap system (74.6±27.13% of 463.4±296.87?mg FOG/L) for the treatment of barbeque restaurant wastewater. Similarly, matrix-based system revealed higher chemical oxygen demand removal (85.9±11.99%) than the typical trap system (60.4±31.26%). Characterizations of the influent, emulsified, adsorbed and effluent FOG indicated that straight saturated fatty acids constituted the cause of clogging problems in the FOG-trap and piping system.