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 $\le 1,000\text{mg}/\text{L}$ . However, the typical trap showed lower FOG removal efficiency than the matrix-based system when the influent FOG concentration was increased to $\ge 5,000\text{mg}/\text{L}$ . In addition, the matrix-based trap system was able to sustain a stable high FOG removal, with $<100\text{mg}/\text{L}$ 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 ( $92.7\pm 9.06\%$ of $1,044.8\pm 537.27\text{mg}$ FOG/L) than in the typical trap system ( $74.6\pm 27.13\%$ of $463.4\pm 296.87\text{mg}$ FOG/L) for the treatment of barbeque restaurant wastewater. Similarly, matrix-based system revealed higher chemical oxygen demand removal $\left(85.9\pm 11.99\%\right)$ than the typical trap system $\left(60.4\pm 31.26\%\right)$ . 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.