Currently, chemical methods are widely used. This technology route uses strong acids and bases as catalysts to complete the esterification and ester exchange reactions of fats (fatty acids) with low-carbon alcohols such as methanol or ethanol. This scheme has a high reaction temperature (usually 110-130 ℃), fast reaction rate, and high conversion rate. However, due to the use of acid-base catalysts, the equipment is severely corroded, and more importantly, it brings a large amount of wastewater and waste residue that is not suitable for biochemical treatment, which puts great pressure on environmental protection.