| EC – Electro-coagulation system
Electrocoagulation (EC) system for the removal of contaminants from water, including heavy metals, FOG (Fat-Oil-Grease), dyes, suspended particles, chemical and mechanical polishing waste, organic matter from landfill leachate, defluorination of water, synthetic detergent effluents, waste from pulp and paper industries, food and beverages processing, construction sites, mining and metal processing.
In the EC process a coagulant is generated in situ by electrolytic oxidation of an appropriate anode material.
Introducing highly charged metal and metal hydroxide substances.
These substances neutralize the electrostatic charges of ionic species present in water and cause them to agglomerate
Agglomeration or coagulation of the above ionic species results in separation from the aqueous phase.
In addition, this treatment prompts the precipitation of certain metals and salts.
The mechanism of EC is highly dependent on the chemistry of the aqueous medium, especially conductivity. In addition, other characteristics such as pH, particle size, and chemical component concentrations will also influence the EC process.
Electrocoagulating reactor is made up of an electrolytic cell with anodes and cathodes in parallel arrangement.
Alternating current and voltage are applied to these electrodes.
The electrodes may be made up of the same or of different materials.
Electrocoagulation using an aluminum electrode:
The electrolytic dissolution of the aluminum anode produces the cationic monomeric species such as Al3+ and Al(OH)2+ at low pH, which at appropriate pH values are transformed initially into Al(OH)3 and finally polymerized to Aln(OH)3n according to the following reactions:
Al → Al3+ (aq) + 3e− (1)
Al3+ (aq) + 3H2O → Al(OH)3 + 3H+ (aq) (2)
nAl(OH)3 → Aln(OH)3n (3)
These charged substances can effectively remove pollutants by adsorption mechanism or by charge neutralization.
Electrocoagulation using an iron electrodes:
Iron oxidation in an electrolytic system produces iron hydroxide, Fe (OH)n, where n = 2 or 3.
4Fe(s) + 10H2O(l) + O2(g) → 4Fe(OH)3(s) + 4H2(g)
Fe(s) + 2H2O(l) → Fe(OH)2(s) + H2(g)
The Fe(OH)n(s) formed remains in the aqueous stream as a gelatinous suspension, which can remove the pollutants from wastewater either by complexation or by electrostatic attraction, followed by coagulation.
Advantages:
EC can handle the most dramatic, dirty, polluted wastewater imaginable, but for a price.
No need for chemicals, hence environmentally friendly.
EC systems are simple, easy to operate and virtually maintenance-free.
Wastewater treated gives palatable, clear, colorless and odorless water.
Sludge formed by EC tends to be readily settable and easy to de-water.
EC floc contains less bound water, is acid-resistant and more stable than chemical floc.
The gas bubbles produced during electrolysis can carry the pollutant to the top of the solution, where it can be easily concentrated, collected and removed.
Disadvantages:
The electrodes dissolve as a result of oxidation, and need to be regularly replaced.
Depending on the degree of improvements required, the cost price might be prohibitive: an EC system that has to improve COD, BOD, FOG, TSS, heavy metals, and so on, with 90% can be 4-6 times more expensive than when an improvement of 60-70% is adequate.
The use of electricity may be expensive.
EC systems are custom-made, based on wastewater characteristics and expected results.
Application
Water from wells, rivers, lakes and other natural sources,
sewage,
rinse & wash water,
recycled water,
wastewater from industrial processes,
and groundwater cleanup
Users
Industries, commercial enterprises and utilities companies that treat, process and utilize water, wastewater and sewage
Capacities: 1 m3/h - 50 m3/h
All systems are custom-made, based on:
Application
Location and environment
Water source, properties and volume
Desired treated water properties and volume |