Electro Treatment (ET) including electrocoagulation (EC), electroflotation (EF) and electroxidation (EOx) is a broad-spectrum treatment technology that removes total suspended solids (TSS), heavy metals, emulsified oils, emulsions bacteria and a broad range of other contaminants from water.
Electro treatment, the passing of electrical current through water, has proven very effective in the removal of contaminants from water.
ET systems have been in existence for many years (Dieterich, patented 1906), using a variety of anode and cathode geometries, including plates, balls, fluidized bed spheres, wire mesh, rods, and tubes.
The ET process is based on scientific principles involving responses of water contaminants to strong electric fields, currents, and electrically induced oxidation and reduction reactions. Depending on the solution matrix, this process is able to remove heavy metal cations and also appears to be able to disrupt cell wall or cell membrane of microorganisms in the water to disinfect. It is also able to precipitate charged colloids and remove significant amounts of other ions, colloids, and emulsions. Potential applications to agriculture and quality of rural life include removal of pathogens and heavy metals from drinking water and decontamination of food processing wash waters.
Coagulation is one of the most important physiochemical operations used in water treatment. This is a process used to cause the destabilization and aggregation of smaller particles into larger particles. Water contaminants such as ions (heavy metals) and colloids (organics and inorganics) are primarily held in solution by electrical charges. Schulze, in 1882, showed that colloidal systems could be destabilized by the addition of ions having a charge opposite to that of the colloid (Benefield et al., 1982). The destabilized colloids can be aggregated and subsequently removed by sedimentation, flotation and/or filtration. Coagulation can be achieved by chemical or electrical means.
Chemical coagulation is becoming less acceptable today because of the higher costs associated with chemical treatments (e. g. the large volumes of sludge generated, and the hazardous waste categorization of metal hydroxides, to say nothing of the costs of the chemicals required to effect coagulation). It has been used for decades to destabilize suspensions and to effect precipitation of soluble metal species, as well as other inorganic species from aqueous streams, thereby permitting their removal through sedimentation or filtration. Alum, lime, and/or polymers have been the chemical coagulants used. These processes, however, tend to generate large volumes of sludge with a high bound water content that can be slow to filter and difficult to dewater. These treatment processes also tend to increase the total dissolved solids content of the effluent, making it unacceptable for reuse within industrial applications.
Electrocoagulation can often neutralize ion and particle charges, thereby allowing contaminants to precipitate, reducing the concentration below that possible with chemical precipitation, and can reduce or replace the use of expensive chemical agents (metal salts, polymer).
Although the electrocoagulation mechanism resembles chemical coagulation in that the cationic species are responsible for the neutralization of surface charges, the characteristics of the electrocoagulated floc differ dramatically from those generated by chemical coagulation. An electrocoagulated floc tends to contain less bound water, is more shear resistant, and is more readily filterable.
Electroflotation (EF) is the flotation using electrolytically generated bubbles of hydrogen and oxygen for separating suspended substances from aqueous phases. it is an intergral part of the electro treatment process and the H2OClean equipment is designed to take full advantage of it.
This process was first proposed by Elmore in 1905 for flotation of valuable minerals from ores. Compared with the conventional dissolved air flotation (DAF), EF has many advantages, including high flotation efficiency, compact units, easy operation, and less maintenance. Therefore, EF is an attractive alternative to DAF. This technique has been proven very effective in treating oily wastewater or oil-water emulsion, mining wastewater, groundwater, food processing wastewater, restaurant wastewater, industrial sewage, heavy metals containing effluent, and many other water and wastewaters.
In wastewaters with very high levels of organic contamination, such as dairy, cheese, meat and food processing,, dissolved air can be added to the EF to provide enhanced separation.
Domestic and Industrial processes generate huge amounts of hazardous effluents every day. Conventional treatment techniques, such as biological methods (aerobic and anaerobic treatment) and chemical coagulation, are commonly applied to clean up wastewaters. Tertiary treatment methods such as ultrafiltration, ozonation, adsorption and UV light disinfection have been used to provide disinfection for decades. However, these techniques are not capable of removing all harmful compounds, micropollutants and pathogens from wastewater. This is where Advanced Oxidation is utilised. This typically with ozone, hydrogen peroxide, very high doses of UV, alumina catalysts utilise and Fenton's reaction is used. However, there is an easier way.
Interest in water treatment by electrochemical methods has grown in recent years. Electrochemical oxidation, or EOx for short, has been applied successfully to degrade different organic pollutants and disinfect drinking water and municipal wastewaters. Also, many industrial wastewaters, such as textile, olive oil, pulp and paper mill and tannery effluents have been treated successfully by this technique.
EOx electrochemical oxidation can be used to treat effluents from different sources and also to disinfect different microbes present in wastewaters and drinking water.