Research On Pollutants Removal By Submerged Plant-microbial Fuel Cell

River pollution has seriously affected the health of human environment and restricted social and economic development.Submerged plant microbial fuel cell?SP-MFC?makes up for the shortcomings of existing river restoration techniques,such as large energy consumption,complex structure,and poor treatment effects of nitrogen and phosphorus.In order to simultaneously recover energy and strengthen the removal of pollutants in water and sediment,SP-MFC was constructed.Pollutants removal mechanisms were analyzed in terms of operating conditions,plants and enzymes.The primarily work and achievements are as follows.Electricity production was monitored during the experiment.Microbial Fuel cells?MFCs?coupling submerged plants generated more electricity than the blank control.Voltage of each group is 321 mV for Ceratophyllum demersum L group,317 mV for verticillata group,311 mV for Hydrilla Richgroup,264 mV for the blank control.Ceratophyllum demersum L group performed the best in power generation,with its maximum power density as 98.70 mW/m².Results of cyclic voltammetry showed that the redox activity of the plant group was higher than that of the blank group.Pollutants removal efficiency of different submerged plants in the systems was investigated.Submerged plant improved pollutant removal rate in both solid and liquid phase.Ceratophyllum demersum L group performed the best in COD,TN and TP removal,with its removal rate as 81.54%?65.27%and 79.10%,respectively.Differences of NH₃-N removal rate among groups are not significant.Ceratophyllum demersum Lalso topped the list of sediment remefdiation,with its removal rate of total organic matter,TN,TP as43.77%,26.49%,21.42%,respectively.MFC?17.63%?contributed more to COD removal than plants,while plants?24.64%?contributed more to total phosphorus removal.Effect of electricity generation on pollutant removal was analyzed.Good correlation between voltage and removal rate of COD and NH₃-N and TN was obtained.During the stable operation period,the growth rate of the biomass of the Ceratophyllum demersum L closed-circuit group was 17.67%,which was significantly higher than that of the open-circuit group.Root exudates and Root oxygenation of the Ceratophyllum demersum L closed-circuit group were significantly higher than those of open-circuit group,and the root oxygenation was consistent with the voltage and the removal rate of COD and TP.Enzyme activity of systems with plants was significantly higher than blank group.The ATPase and dehydrogenase activities of the Ceratophyllum demersum L group were 1.42and 1.45 times that of the blank control respectively.The enzyme activity of Ceratophyllum demersum L closed circuit group is significantly higher than that of the open circuit group,except for the nitrite reductase.Activity of cathodic nitrogen removal-related enzyme in the system is significantly higher than that of the anodic ones,and the activities of hydroxylamine oxidoreductase and ammonia monooxygenase are higher.Total phosphorus and inorganic phosphorus removal rate in sediment are consistent with activity of alkaline phosphatase,while organic phosphorus showed a different trend,which was probably due to its diversed transition route.