Study On Plant Purification Coupling Electrochemical Oxidation Process For Treatment Of River Wastewater

Water pollution and resource shortage were challenges of the water environment.As an important part of water environment,surface runoff was often polluted by domestic sewage and industrial wastewater.River pollution had affected the ecological environment and normal human activities.Therefore,more and more researchers began to pay attention to river pollution.Five aquatic plants of Hydrocotyle chinensis,Cyperus alternifolius,Acorus calamus,Pistia stratiotes and Eichhornia crassipes were selected to construct single plant unit and combinatorial plant unit.Cobblestones were used as a substrate for fixing aquatic plants.Under the conditions of single and combinatorial planting,the effects of aquatic plants on the removal of ammonia nitrogen and Chemical Oxygen Demand?COD?in river wastewater were investigated.The optimum group of aquatic plants was determined by experimental determination.The electrochemical oxidation method was used to further treat the wastewater after plant purification.Ti/IrO₂-Ta₂O₅ was used as the anode and red copper was used as the cathode.The effects of different electrolysis time,electrolyte concentration,current density and initial pH on COD removal were investigated.The optimal condition of electrochemical experiment was determined.In the single plant unit,the Hydrocotyle chinensis showed a better purification effect.When the treatment time was 10 d,the removal efficiency of ammonia nitrogen and COD of Hydrocotyle chinensis group were 77.88% and 27.02%,respectively.In the combinatorial plant unit,Acorus calamus and Pistia stratiotes group had better removal effect on ammonia nitrogen and COD,with removal rates of 81.06% and 30.44%,respectively.For the degradation of pollutants in wastewater,cobblestones mainly manifested as physical adsorption.The results of the electrochemical performance test,scanning electron microscope and energy dispersive spectrometer analysis of the Ti/IrO₂-Ta₂O₅ anode,it showed that the anode used had good reversibility and excellent electrocatalytic activity in electrolysis of wastewater.In the electrochemical experiment,when the NaCl concentration was 9mmol/L,the current density was 10 m A/cm²,the initial pH was 3.0,and the electrolysis time was 60 min,the COD removal effect was the best,and the removal rate was 79.75%.After the plant purification coupling electrochemical oxidation process,the removal rate of ammonia nitrogen reached more than 99%,and the removal rate of COD was 85.91%.The effect of coupling process on wastewater treatment is better than that of plant purification.The service life of the electrode is prolonged by avoiding contact with high concentration of wastewater.It is a useful attempt in the development of water treatment.Figure 36;Table 17;Reference 75.