Effects Of A Lake Sediment Microbial Fuel Cell On Phosphorus Transport And Transformation

Sediment microbial fuel cells(SMFCs)can inhibit release of endogenous phosphorus while generating electricity and removing organic matter.However,there are few reports on the changes in the vertical phosphorus form and the distribution of the TP in sediemnts due to the pH change and the induced sulfur oxidation process caused by the operation of SMFCs.Thus,through indoor simulation experiments,the SMFCs system for different types of sediments was built,the Rhizon sampler was used to continuously collect pore water,and the microelectrode interface monitoring system was used to monitor the changes in the vertical external environmental indicators in the overlying water and sediments,and the study further explored the effect of SMFCs on sedimentation.By studying the influence of the vertical distribution of phosphorus can provide a reference for the restoration of lake ecosystems.The main research contents and conclusions are as follows:(1)In SMFCs,the pH in sediments and overlying water ranged from 4.63 to 8.26.The pH value in the control group was stable at 6.8.SMFCs significantly changed the pH of sediment and overlying water.The TP content(0.05 mg/L)in the overlying water of SMFCs was much lower than the control group(0.14 mg/L).With the increase of sediment depth,the concentration of SRP in the interstitial water of SMFCs increased from 0.018 mg/L to 1.090 mg/L.The proportion of each phosphorus form in the sediment in the TP is:Na OH-P>HCl-P>OP>BD-P>NH₄Cl-P.At the same time,the phosphorus form in the upper 4 cm of the sediment changes greatly.There was a significant positive correlation between the SRP concentration in the interstitial water and pH(r=-0.930,P<0.01).The phosphorus forms(NH₄Cl-P,BD-P,OP)were not correlated with SRP(P>0.05),the pH induced by SMFCs had a significant effect on SRP in the interstitial water.(2)SMFCs could continuously inhibit the release of endogenous phosphorus,and the induced sulfur oxidation process reduced the release of endogenous phosphorus.During the experiments,the SRP in pore water and overlying water of SMFCs both decreased significantly.The ion migration brought by the SMFCs was affected by the internal resistence and remained in the sediments to promote the acidification of the sediments.The anode located in the sediments and the cathode embedded in overlying water inducee sulfur oxidation,accelerated the dissolution of Fe S and promoted the formation of iron oxide and the fixation of phosphorus in the sediment.At the same time,the embedding of anode cabon felt in the sediment changed the microbical community structure and promote the enrichment of sulfur oxidzing bacteria on the anode and cathode carbon felts.The relative abundance could reach 5.515%and4.189%,repectively,which further strengthened the sulfur oxidation process in the sediments.This study shed new lights on the study of SMFCs'inhibition on endogenous phosphorus release and provides theoretical basis and data support for reducing the release of endogenous phosphorus,improving the status of lake sediments,and realizing the construction of a benign lake ecosystem.