A food factory constantly releases waste containing oil and fat into its wastewater treatment system. To obtain zero waste, the waste should be utilized as an energy source, such as biofuel oil (BFO). In this study, waste fat containing 86.13%wt. of free fatty acid (FFA) was converted to BFO through esterification. Effects of methanol-to-FFA molar ratio, amount of catalyst, reaction time and reaction temperature on the production were investigated and used to find model-based conditions that produced BFO at the desired 90% FFA conversion and 96% yield. The results showed that a molar ratio 5:1 with 6 %wt. H2SO4 and reaction temperature of 60oC for 30 minutes gave BFO that met the specifications of fuel oil no. 4. The production costs at these conditions were 423.89 US$/ton BFO, which is below the combined costs of boiler fuel and waste disposal. Therefore, such conversion of waste fat to BFO is economic.
