Evaluation of the efficacy of subcritical water to enhance the lipid fraction from activated sludge for biodiesel and oleochemicals production

摘要

Activated sludge is currently being investigated as a potential feedstock to produce biodiesel. Reports have shown that its lipid yield is usually low, compared to the commercially available feedstocks, such as soybean, sunflower, and rapeseed oils. The current work is geared toward investigating the potential of enhancing the total lipid yield (neutral and phospholipid) by the application of subcritical water. The results show that subcritical water treatment increased the total lipid yield by 145% at the optimum conditions 280 degrees C, 40 min, 15 mL of water and biomass loading of 5%. The lipid classes identified were waxes, acylglycerol, sterol, free fatty acid, and phospholipids. The results of the fatty acid methyl esters analysis revealed palmitic acid as the predominant fatty acid. Practical applications The practical applications of the results are informed from the improved lipid yield obtained, suggesting that subcritical water treatment is essential if activated sludge were to be a viable feedstock for biodiesel, renewable diesel, and oleochemicals productions. This will serve as a sustainable activated sludge disposal strategy.