Study On Electricity Generation In Microbial Fuel Cell With Biodiesel By-Product

With the rapid development of biodiesel industry, a new problem which is how to use the biodiesel by-product has occurred. Glycerin refining was the traditional method of biodiesel by-product using, but under the pressure of the selling price descending, it is not economic any more. The MFC using biodiesel by-product as substrate is a new research aspect, and it also provides a method of biodiesel by-product application.MFC with biodiesel by-product was studied in air-cathode single chamber reactor on the effect of COD-concentration of influent, composition of biodiesel by-product and PBS. Power density range from 161 mW/m2 to 371 mW/m2 was obtained with the adding of 390 mg/L,780 mg/L,1020 mg/L,1960 mg/L,3920 mg/L and 7850mg/L-COD influent. Maximum COD removal 95% was achieved in 3920 mg/L-COD influent and coulombic efficiency were all about 6%. Theoretical maximum power density 387 mW/m2 was obtained by Monod equation fitting. Production process of biodiesel has affect on by-product composition and further influence the performance of MFC. By increasing the separation time of biodiesel and by-product from 1 h to 24 h, the by-product was added into reactor, obtaining 487 mW/m2 power density and coulombic efficiency 9.01% compare with 333 mW/m2 and 5.97%. The ideal maximum power density was obtained using pure glycerin as substrate.Biodiesel by-product is complicated in composition and its COD is extremely high, the power density and coulombic efficiency couldn't meet the requirement because of the existence of small amount of lipid. Several pretreating methods (substrate treated by 800W microwave, adding Tween 80 and surface modification of anode material) were conducted according to characteristics of biodiesel by-product in order to enhance the performance of MFC. Pre-treatment of microwave largely decreased the starting time and improved the coulombic efficiency significantly. Another method of adding surfactant into substrate did not obtain good results, power density was just increased 14mW. Carbon fiber brush was used as anode and it increased 67.9% power density of MFC with carbon cloth anode. High temperature treatment, acid treatment and alkali treatment were carried out to carbon fiber brush anode, MFC achieved much higher power density2.11 W/m2. MFC with biodiesel by-product achieved favorable performance.