Preparation Of Titanium Dioxide Electrode And Its Performance In Removal Of Microcystis Aeruginosa

The process of urbanization in China is becoming faster and faster,leading to daily increase in the amount of domestic sewage and industrial waste water.But before that,people didn't have a strong sense of environmental protection.Many domestic sewage and industrial wastewater are discharged into the natural world without any treatment.Causing natural water bodies to exceed their self-purification capacity.Nitrogen and phosphorus in water are seriously over standard,which results in large eutrophication of water.The important reason for eutrophication is the excessive reproduction of algae in the water,and the explosion in the lake or other waters.The outbreak of algae in natural waters usually has an incalculable impact on the supply of drinking water.Algae grow themselves,and a series of substances released in water can cause many diseases of aquatic organisms and human beings.Incalculable damage and harm to aquatic ecosystems.In the eutrophication of fresh water,the main algae is Microcystis aeruginosa.When the ballast water contains the algae,the hull reaches another area and the ballast water is discharged,and the algae is introduced into another water body when the ballast water contains the algae.When the water quality of another water area is suitable,Microcystis aeruginosa will have a very high potential risk to cause eutrophication in another water area.Therefore,in this study,a simple electrochemical reactor was used to investigate the effect of electrochemical high-level oxidation on Microcystis aeruginosa(often called cyanobacteria)under different experimental conditions.The structure of the electrochemical reactor is as follows: the anode is a titanium dioxide electrode material,and the cathode is a stainless steel net.In the experiment,the Microcystis aeruginosa suspension containing algae(1.3-1.1× 1010 Per liter)was placed at a current density of 1 mA/cm2 to 10 mA/cm2 for advanced electrochemical oxidation treatment with a reaction time of 2 h.In the reaction process every 0.5 h sampling,monitoring cyanobacteria cell density,chlorophyll a content,the p H value of the water and the water conductivity and COD solution and other macromolecules(proteins and humus)changes.When the current density was 10 mA/cm2,the cell density of Microcystis aeruginosa decreased very rapidly after pretreatment with advanced electrochemical oxidation of 30 min.Algal density decreased from 1.3×1010 to 6.9×109 Per liter.After 120 min treatment,the algal cell concentration decreased from 1.3×1010 to 6.2 ×109 Per liter.According to the experiment,it can be concluded that the change of quantity and light density of Microcystis aeruginosa is positively related to applied current density and treatment time.By scanning electron microscopy,we can see clearly that after the electrochemical oxidation,the cell membrane of Microcystis aeruginosa has been seriously damaged,so that the cytoplasm of the cells in a large number of leakage.Because of the damage of cells,the chlorophyll-a is infiltrated from the cell to the solution,and then can be oxidized by electrochemical reaction to remove it.When the applied current density was 10 mA/cm2,the chlorophyll removal rate of algae was close to 90%.Moreover,the electrochemical reaction resulted in obvious change of p H and conductivity of water,which accelerated the removal efficiency of chlorophyll-a.And after the treatment of algae growth may be almost no again,when the applied current density is 10 mA/cm2,only 15 min after treatment,after treatment with algae aseptic technique re cultured under suitable conditions.The change of light density value(algae concentration)of 8 days early solution was monitored continuously.Through experiments,we found that Microcystis aeruginosa cells did not show any signs of growth and survival.The value of optical density has been decreasing,and the whole solution has changed from light green to muddy yellow.The above experiments fully proved that electrochemical advanced oxidation can successfully and efficiently kill Microcystis aeruginosa,an important object for eutrophication.And it can make algae cells lose their activity in a short time.This fully shows that electrochemical advanced oxidation has a broad application prospect and value in the process of eutrophication water purification.