The Study Of Remediation Of Co-Contaminated Soil With Soil Microbial Fuel Cells

In this study, soil microbial fuel cells (MFCs) were constructed, which fueled with organic pollutants in soil. Electricity generation characteristics and pollutant degradation rate of MFCs were tested. The study has achieved good results.It has been proved that the soil microbial fuel cells can simultaneously remove pollutant and generate electricity for a long term. The operation cycle of MFCs is 175 days; stable voltage is 270±5 mV; cumulative discharge is 3081 C; maximum power density is 12.1 mW·m-2; internal resistance is 500?. The degradation rates of petroleum hydrocarbon, pyrene, anthracene and phenanthrene are 40.05%,54.19%,42.60%,27.02% respectively. Compared with disconnected MFCs, the degradation rates enhance 150.78%,160.15%, 145.67%,131.93% in the experiment of closed circuit respectively. The microorganism in soil and anode have been domesticated after the operation of MFCs. Electricigens enriched in the surface of anode and Geobacter became the dominant bacteria. Several species of microorganisms which can degrade petroleum hydrocarbon have been detected in soil and anode, such as Pseudomonas and Microbacterium.Electricity generation characteristics and pollutant degradation rate of MFCs were tested by different electrode spacing ranged from 4 to 10 cm. The experiment result showed that soil MFCs with smaller electrode spacing had better electricity generation characteristics and higher pollutant degradation rate. The voltage and maximum power density of the MFCs with 4 cm electrode spacing reached 285±5 mV and 12.1 mW·m-2, respectively. When the electrode spacing were 4 and 6 cm, the degradation rate of petroleum hydrocarbon, pyrene, anthracene and phenanthrene were similar, which were apparently higher than that of 8 and 10 cm electrode spacing. The maximum degradation rates of petroleum hydrocarbon, pyrene, anthracene and phenanthrene were 24.3%, 18.8%,34.1%,28.1% respectively. The MFCs with smaller electrode spacing have lower resistance of mass transfer, so the performance is improved.Electricity generation characteristics and pollutant degradation rate of MFCs were tested by different depth of overlaying water from 1 to 7 cm. The experiment result showed that the stable voltage of five soil MFCs ranged from 254 to 287 mV, and the maximum power density ranged from 10.5 to 12.3 mW·m-2. The internal resistance of the five soil MFCs were 500?. So the depth of overlaying water have no effect on the electricity generation performance of soil MFCs. Similarly, there is no significant influence on the degradation rate of petroleum hydrocarbon, pyrene, anthracene and phenanthrene.