Coal-based Porous Carbon Membrane Coupled With Electric Field For The Enhanced Microalgae Removal From Simulated Ballast Water

With the rapid development of international trade,the shipping business is booming.The pollution problem caused by marine biological invasion is more and more serious.And the damage to the marine environment is also becoming more and more grievous.So it has been recognized by the Global Environment Facility as one of the four major threats to the marine environment.Therefore,in order to protect the marine environment,we need to control and reduce the pollution of the marine biological invasion intensified effectively and to continue to study more and better marine antifouling technology which is a hot topic in research and explore in the field of marine science.In this paper,an integrated membrane/electrode treatment system combining the electrochemical oxidation process was designed by using the specific conductivity of coal-based porous carbon membrane.The carbon membrane was set as an anode and coupled with the external electric field to deal with the simulated ballast water prepared by Chlorella vulgaris,Nitzschia closterium and Platymonas subcordiformis.The effects of various parameters including microalgae species,microalgae concentration,electric field intensity,and electrical conductivity on the separation performance were carried out.The contamination of membrane surface and cross-section before and after carbon membrane treatment was observed by scanning electron microscope(SEM).The experimental results show that the electric field intensification of the coal based porous carbon membrane shows a good treatment effect on the removal of microalgae in the simulated ballast water.Compared with the no electric field,the permeation flux has been greatly improved.With the increase of the electric field intensity,the penetration process of the system can be strengthened and the permeation flux is increased.Increasing the electrical conductivity of simulated ballast water increases the electrochemical reaction on the surface of the membrane.The produced gas can block the contamination of the microalgae cells to the carbon membrane and increase the permeation flux.It is also found that increasing the concentration of microalgae can reduce the permeation flux.The species of microalgae are also one of the factors affecting the permeation flux.The results showed the large size of the Platymonas subcordiformis tended to form a thick fouling layer on the carbon membrane,resulting in low permeate flux.In order to further explain the antifouling ability of coal based carbon membrane strengthened by electric field.In this paper,the analysis of anti-pollution parameters of coal based porous carbon membrane under the condition of adding electric and no electric fields has been carried out.The results show that the treatment system showed enhanced permeate flux and fouling resistance by coupling with electrochemical oxidation process.After cleaning,the treatment system still kept high permeates flux,implying its good regeneration ability.In order to prevent the by-product of electric field enhancement of coal based porous carbon membrane system after the treatment of ballast water may produce adverse effects on the environment,therefore,we need to detect the associated by-products of the ballast water after treatment.In this paper,the content changes of halogenated hydrocarbons in the ballast water under different electric field intensities were treated by an electric field enhanced coal based porous carbon membrane system.The detection results showed that with the increase of electric field intensity,the contents of three other substances such as CHBr3,CHClBr2 and CHCl3 changed greatly except for the change of CHCl2Br concentration.Under the electric field intensity of 0 V/cm,0.15 V/cm and 0.31 V/cm,the content of the 4 substances conforms to the WHO standard.When the strength of the electric field is 0.46 V/cm,the content of CHBr3 and CHClBr2 does not conform to the WHO standard.The best electric field intensity used in this paper is 0.31 V/cm,so the three halogenated methane in ballast water will not be harmful to the environment after electric field enhanced coal based porous carbon membrane system.