Abstract
In recent years, lipids reused from urban wastewater materials have come to prominence as possible raw materials for biodiesel production. The present work investigated liquefied dimethyl ether (DME) for the lipid extraction of fat balls from sewage pumping stations. A response surface methodology (RSM) based on a Box-Behnken design (BBD) was utilized to optimize DME extraction parameters (sample size, velocity of liquefied DME, and DME/sample ratio). The maximum lipid yield was 65.2% under optimal DME extraction conditions (sample size 1 mm, velocity of liquefied DME 3.3 m/h, and DME/sample ratio 80 mL/g). Under the optimum conditions, the DME technique exhibited higher lipid recovery than that of mechanical shaking extraction (49.0%) or Soxhlet extraction (62.0%). The extracted lipids were converted into biodiesel, resulting in an approximately 35.2-46.2% biodiesel yield. Furthermore, the fatty acid methyl ester composition of the extracted lipids was characterized. These significant findings highlight the promising potential of fat balls as sustainable biodiesel feedstocks and provide valuable insight that will aid the development of better technology for lipid extraction.