Electricity Generation Of Surplus Sludge Microbial Fuel Cell Enhanced By Biosurfactant

Mcrobial fuel cell (MFC) is a highly efficient and cleaning technology, which notonly can use single carbohydrate as fuel to generate energy, but also can be applied tothe treatment of pollutants such as sewage, sludge, landfill leachate and so on, and ithas the advantages of low power consumption, short residengce time and mildreaction conditions, etc. The main ingredients of surplus sludge are protein,carbohydrate and fat isometric chain molecule organic matter, so surplus sludge is apotential fuel for MFC. However, we find that MFC can only use souble organicmatter to generate energy, while the organic matter of sludge mainly exists in the solidphase. For this, we expect to improve the efficiency of electric generation and organicmatter degradation of the MFC reactor by increasing the efficiency of sludgehydrolysis and the quantity of souble organic matter in the sludge.Biosurfactant can effectively strengthen the sludge hydrolysis, improve sludgedegration rate and shorten the sludge digestion time. In the paper, we combinedrhamnolipid with surplus sludge MFC to investigate the effects of rhamnlolipid on theperformance of electricity production and the reduction of excess sludge. The resultsindicated that rhamnolipids greatly enhanced the performance of electricitygeneration and the reduction of surplus sludge. When the best rhamnolipid addtiveconcentration was0.3g·gTSS-1, the maximum output power density and coulombefficiency were516.7mW·m-2and11.8%, respectively; the efficiency of reducingTCOD, TSS and VSS were58.5%，56.7%and66.3%, respectively. While withoutrhamnolipid, the maximum output power density and coulomb efficiency were only236.8mW·m-2and5.7%, respectively; the efficiency of reducing TCOD, TSS andVSS were only28.6%,28.9%and33.4%,respectively. During the system operation，the SCOD，protein and soluble sugar concentrations of surplus sludge were first risethen come down.In this paper, the effect of pH and ramnolipid on the performance of electricityproduction and the reduction of excess sludge in surplus sludge MFC was discussed.The results demonstrated that the electrogenesis characteristics of surplus sludgeMFC at alkaline pHs(pH=8.00,9.00) was superior to the neutral (pH=7.00) and acidiccondition (pH=5.00,6.00)；the reduction of excess sludge at alkaline pH(8.00，9.00，10.00) was better than acidic condition(pH=5.00,6.00). When only adjust pH ofexcess sludge(without ramnolipid), the maximum output power density and coulomb efficiency achieved279.87mW·m-2and6.5%at pH9.00; when pH and ramnolipidcombined effect, the maximum output power density was increased to582.39mW·m-2at pH8.00while the maximum coulomb efficiency was12.9%at pH9.00. The resultsindicated that the rhamnolipid enhanced the output power characteristics when theinitial pH was8.00and9.00.