| The problem of eutrophication in Taihu Lake is worsening day by day,and the water quality declines rapidly.However,the endogenous pollution of sediments is the key factor of lake eutrophication,especially the release of nitrogen and phosphorus nutrition sources.Electrokinetic remediation is an emerging in situ deposition repair technique that has been applied in recent years to remove heavy metals and organic contaminants in soil sediments and sewage.Aiming at the problem of eutrophication in Taihu Lake,this paper proposes to use electrokinetic remediation technology to repair nitrogen and phosphorus pollution in the sediments of Taihu Lake.The feasibility of using electrokinetic remediation technology to repair nitrogen and phosphorus in Taihu Lake sediment was studied.The influencing factors of pollutant removal efficiency after electrokinetic remediation,the energy consumption accumulated in the process of electrokinetic remediation,the electrode products and the migration and transformation of phosphorus started research(1)The electrokinetic remediation technology can be used for the removal of nitrogen and phosphorous pollution in sediments of Taihu Lake.When the iron plate is used as the anode and the graphite is used as the cathode,the distilled water is used as the electrolyte,after being electrokinetic remediation by a constant voltage gradient of 1.0 V/cm for 7 days,the average removal rate of phosphorus was 17.7%,the average removal rate of nitrate nitrogen was 24.2% and the average removal rate of organic matter was 15.8%.(2)In the electrokinetic remediation process,the current increases with the repair time first and then decreases.The sediment temperature shows an increase from the anode to the cathode and then decreases,and the temperature in the middle position is the highest.After electrokinetic remediation,the p H of the sediment shows an acidity near the anode to the alkalinity near the cathode,and increases continuously.(3)The type of electrolyte and electrode plate,the magnitude of voltage gradient,and electrokinetic remediation time all affect the removal efficiency of pollutants after electrokinetic remediation.As the voltage gradient increases,both the current magnitude and the pollutant removal efficiency increase.Compared with titanium anodes,iron anodes can achieve better total phosphorus removal efficiency.Compared with starch solutions,acetic acid solutions have little difference in the removal rates of total phosphorus and nitrate nitrogen,but they can achieve better removal efficiency of organic matter.The repair effect increases as the repair time increases,but when the electric repair reaches a certain time,increasing the repair time does not significantly increase the removal efficiency of the pollutants,but instead increases the power consumption and increases the operating costs.(4)Under the voltage gradient of 2.0V/cm for 7 days,the iron plate as the anode,the graphite as the cathode,the distilled water as the anode electrolyte and the 0.5mol/L acetic acid as the cathode electrolyte gave the maximum average removal rate of total phosphorus54.53%,nitrate nitrogen 67.38% and organic matter 30.77 %.(5)In the process of electrokinetic remediation,the accumulated power consumption increases with the increase of voltage gradient and electrolyte concentration.When acetic acid is used as the electrolyte,the iron anode is seriously corroded and the graphite electrode quality is basically unchanged.When starch is used as the electrolyte,the quality of the iron anode and the titanium electrode is basically unchanged,and the graphite electrode is attached due to the crystals produced by the cathode,and the quality is increased.(6)The process of phosphorus removal during electrokinetic remediation is mainly represented by H2PO42-,HPO42-moving toward the anode and Fe3+ produced by the anode to produce Fe HPO4+ and Fe H2PO42+.These positively charged complexes are transported to the catholyte by electroosmosis and electromigration to effect removal. |
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