The Property And Degradation Effect Research Of Oil Addition In Marine Benthonic Microbial Fuel Cells At Different Conditions

The degradation of oil pollutants on ocean floor is slow for its oxygen-free environment, which has caused long-term harm to the ocean environment. Herein we develop a new technology to manage the pollutant in submarine or coastal beach. The new method is using electro-catalysis effect of marine benthonic microbial fuel cells (BMFCs) to realize in situ bioremediation while promoting the metabolism of microorganism, and thus to accelerate the degradation of oil in the ocean sediments.The operational principle of BMFCs is described as follows:the bacteria in marine sediment decompose the organic pollutants (such as oil pollutants) continuously, producing electronics. The anode is embeded in marine sediment and the cathode is positioned inside sea water. The electron is transferred to the anode through the attachment of bacteria, and then transferred to the cathode by wire. The cathode in seawater reduces oxygen while losing electronic to generate H2O, providing a continuous current. In order to explore the degradation effect of BMFCs on oil and the changes in its properties, this paper has carried out its property and degradation effect research of oil addition in marine benthonic microbial fuel cells at different conditions. The main research results are mentioned as follows:(1)Improve the degradation rate of submarine oil pollutants through the electric-catalysis according to the principle of BMFCs. The influence of oil pollutants on the battery performance is explored by comparing the marine benthonic microbial fuel cells (BMFCs-A) containing oil and oil-free microbial fuel cells (BMFCs-B). The acceleration effect of BMFCs is investigated by the comparison between the oil-degrading rate and the number of heterotrophic bacteria of the BMFCs-A and BMFCs-B on their anodes. The results show that the exchange current densities in the anode of the BMFCs-A and BMFCs-B are 1.37×10-2 A·m-2 and 1.50×10-3 A·m-2 respectively and the maximum output power densities are 105.79 MW·m-2 and 83.60 MW·m-2 respectively. The anti-polarization ability of BMFCs-A is improved. The exchange current densities have increased 9 times and the maximum output power density increased 1.27 times. The heterotrophic bacteria number on their anodes in BMFCs is 66±3.61×107 cfu·g-1 and 7.3±2.08×107 cfu·g-1 respectively, the number of bacterium has increased 8 times in the oil system, which accelerates the oil-degrading rate. The degrading rate of the oil in the BMFCs-A is 18.7 times higher than that in its natural conditions. The BMFCs can improve its electrochemical performance, meanwhile, the degradation of oil pollutants can also be accelerated. A new model of the marine benthonic microbial fuel cells on its acceleration of oil degradation is proposed in this article.(2)Glycolipid biosurfactant can increase the degradation rate of oil alkane. This paper explored the battery property and degradation effect by adding different concentrations of rhamnolipid into oil-free BMFCs. The results show that, anode wettability of anode is increased after the addition of rhamnolipid, the exchange current density and maximum output power density is promoted, the polarization resistance and oil degradation rate are also increased after adding rhamnolipid. The best effect can be got when the concentration of rhamnolipid is 200 mg-L"1. Compared with the blank BMFCs, the contact angle is 48°, which has reduced one times. The exchange current densities is 4.87x10-2 A·m-2, which has increased 38 times. The maximum output power density is140.24 mW·m-2, which increased more than 2 times, the oil degradation rate is increased more than 2 times. This paper puts forward a new mode to accelerate the degradation of petroleum by rhamnolipid and BMFC. This study has instructive significance on the influence of BMFCs accelerating the degradation of submarine oil pollutants.(3)Ammonia-modification and NH4HCO3-electrochemical modification is carried out on anode to explore the influence of ammonia modified anode on the performance of oiliness BMFCs and the effect of the degradation. The results show that the performance of the anode and the battery are both improved after modification, and the effect of NH4HCO3-electrochemical modification is the best. The exchange current densities and the maximum output power density of the NH4HCO3-modified BMFCs are 2.57x102 A·m-2 and 152.87 mW·m2 respectively, which are 5 times as much as the BMFCs without modification. The oil degradation rate increased 8 times after modification. The method of NH4HCO3-electrochemical modification has significantly improved the performance of battery, which has great importance on the research of effect of BMFCs on the oil degradation.