PRODUCTION VALUE-ADDED PRODUCTS FROM BIODIESEL DERIVED CRUDE GLYCEROL

摘要

Crude glycerol, a by-product of biodiesel production which contain impurities such as methanol,rntriglycerides and catalysts, would represent a huge challenge to the environment if disposed. Thus the bestrnopportunity is to convert crude glycerol into valuable products. While a number of microorganisms are able to utilizernglycerol as a sole carbon source to yield a range of organic acids and alcohols, the fermentation process has not beenrnoptimized. The main objective of the study was to evaluate the application of ultrasound to enhance the production ofrnvalue-added acids and alcohols by anaerobic fermentation of crude glycerol. By a method of screening, Clostridiumrndiolis was selected and used in batch fermentation experiments at 37 ℃, pH of 6.8 - 7 and 150 rpm on anaerobicrnenvironment by N2 sparging. Prior to each experiment, crude glycerol was washed three (3) time with diethyl etherrnand a series of glycerol concentrations (50-150 g/L) was fermented for 48 hours with samples taken every 3 hours forrnanalyses. The high-performance liquid chromatography (HPLC) and a light microscopy were used to analyze samplesrnbefore and after the fermentation process. Interestingly, very low amounts of methanol and free fatty acids werernobserved in the washed glycerol after HPLC analysis compared to crude glycerol. Results also demonstrated thernproduction of 1, 3-Propanediol (1, 3-PD) and acetic acid when the fermentation liquor was analyzed by HPLC afterrn48 hours. Moreover, other solvents such as butanol and lactic acid were obtained in very low quantities.rnSubsequently, the effect of ultrasound on the growth of Clostridium diolis was evaluated and lead to enhanced yieldsrnby promoting rapid cellular growth rate. The results thereby indicate that better product yields can be achieved whenrnmicroorganisms are stimulated with low intensity ultrasonic irradiations.