Placing metal aluminum or iron as the anode in the water to be purified, during the electrolysis process, the trivalent aluminum ions or divalent iron ions dissolve from the anode and transfer to the solution, where they hydrolyze into effective flocculants that disperse impurities. The reaction chemical equation of the electrode indicates that oxygen bubbles are produced at the anode.
These bubbles, as they rise, carry suspended matter to the water surface, forming a scum layer. On the other hand, trivalent aluminum ions (or divalent iron ions) and their hydrolyzed polymer products interact with suspended impurities, causing flocculation. The electro-flocculation air flotation method has many characteristics compared to conventional coagulation methods: it eliminates the need for adding any chemical coagulant; it lacks anions and impurities; the electric field formed by the electro-flocculation reactor changes the particles from mutual repulsion to attraction and agglomeration; the O2 and H2 gas bubbles generated during the electro-flocculation air flotation process adsorb light suspended particles or hydrophobic substances, separating them from the water; it can achieve the effect of bacteria removal by removing suspended matter from the water and selecting electrodes. Research shows that when treating domestic wastewater with the electro-flocculation air flotation method, under certain conditions, the turbidity removal rate can reach 95%, and the COD removal rate can reach 59%.
Compared to the chemical coagulation method using flocculants, this method can remove a wide range of pollutants, reacts quickly, has a broad pH range, and produces dense, clear sludge. It is widely applicable to wastewater treatment in industries such as dyeing and printing, dye chemicals, leather, electroplating, etc.
Electroflotation Technology Analysis
Electrolytic Oxidation
(2) Electrolytic Reduction
(3) Electrolytic Flocculation
(4) Electrolytic Air Floatation
Electroflotation equipment function
Electrocoagulation equipment electrode plates can be made of different materials depending on the substance to be removed, producing strong flocculation, strong oxidation, strong reduction, and strong air flotation effects to achieve good treatment results. Commonly used materials include iron, aluminum, titanium, graphite, and lead dioxide. Each material has its suitable application field, and the design of the electrocoagulation equipment and the selection of the electrode plate are determined through extensive research and development tests and rich engineering experience. According to a large number of tests, the electrocoagulation equipment's removal effect on various impurities in wastewater is as follows:
(1) Oil
(2)COD
(3) Turbidity, Suspended Solids
(4) Silicon Dioxide, Colloidal Silicon, Organic Silicon
(5) Heavy Metal Ions
(6) Chroma
(7) Hardness
The basic principle of electrocoagulation technology involves the introduction of electrical current into water, which generates electrical energy to drive chemical reactions between substances. Once these reactions are initiated or forced, various components and compounds will, under the influence of the current, tend to seek a stable state. Typically, this tendency towards stability results in the formation of a solid substance, which exists in a non-colloidal or non-soluble state and is therefore easily removable by subsequent separation techniques.
Electroflotation Device: It adds an electric current to the water flowing into the device through its internally dissolvable plates and a current generator, achieving the goal of coagulating particles in the water into floc for sedimentation. The plates of the electroflotation system are submerged in the water, and an electric current is passed through the plates into the water via an external power source. Under the action of the current, the wastewater undergoes a series of electrochemical processes.
(1) Charge Agglomeration: Once the electrodes are powered, they generate charge, which attracts nearby small particles. This disrupts the original stable state of the material, and by altering the polarity of the particles, the small particles agglomerate to form larger ones, which are then easier to precipitate.
(2) Demulsifying Action: The current decomposes H2O molecules into hydrogen and hydroxide ions.
These hydroxide ions combine with hydroxide ions in molecules of dissolved emulsified oil, sludge, dyes, etc., to form water molecules, while displacing oil, sludge, dyes, etc., to create non-dissolved substances and precipitate.
(3) Formation of Halogen Complexes: After being energized, the plates will simultaneously produce a small amount of metal ions, which combine with chloride ions from chlorinated hydrocarbons in the wastewater to form precipitable complexes. Such pollutants in the wastewater include chlorinated PCBs, etc.
(4) Bleaching and Oxidation: The oxygen ions produced around the plates have both oxidizing and bleaching effects.
(5) Electrolytic Diffusion: The abundant electron flow in the water eliminates the polarity of hydrates, causing colloidal substances to become free and precipitate. Additionally, the increased charge quantity forms osmotic pressure, thereby killing bacteria and the like.
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