What is Electrocoagulation?
The unavoidable increase in the world population and the decrease in clean water resources increase people’s interest in alternative water treatment technologies. Lack of information due to not allocating sufficient funds for water treatment in developing countries brings with it some problems. Industry, which is one of the development indicators of the countries, also uses the existing water resources. The aim is to prevent the pollution of the water environment used both for human needs and industrial enterprises.
Electrocoagulation wastewater treatment was first proposed in England in 1889. Then, a patent was obtained in the USA in 1909 on the treatment of wastewater by electrocoagulation using iron and aluminium electrodes.
The purification of drinking water by large-scale electrocoagulation was first implemented in the USA in 1946.
One of the most important factors in an electrochemical treatment process is the type of electrode used. Generally, aluminium (Al+3) and iron (Fe+3 or Fe+2) electrodes are used in the process. During the process operation, these electrodes react in wastewater and metal hydroxide compounds such as Al(OH)3, Fe(OH)3 and Fe(OH)3 are formed.
These metal hydroxides adsorb different pollution parameters in the wastewater environment and allow it to precipitate. In this way, pollutants are removed from the wastewater.
Pollutants in the wastewater stream are removed by chemically and chemically bonding to colloidal substances formed by chemical/pre-precipitation or abrasion of electrodes. These pollutants are then removed from the system by electroflotation/precipitation and filtration. Thus, instead of adding coagulation agents to the system from outside as in conventional coagulation processes, these substances are produced within the system.
The Electrocoagulation method is used in drinking water treatment and recently in the treatment of paper, pulp, metal, mine, food, oil, textile, and detergent industry wastewater.
Studies have been carried out comparing the electrocoagulation process with other treatment technology in terms of cost and efficiency. These studies have revealed some advantages and disadvantages related to the use of the process.
Advantages; The initial investment cost is significantly lower than alternative technologies. The operating cost is significantly lower than alternative technologies. Requires low energy requirement. There is no chemical addition. It does not require much maintenance. Labour demand is low. The amount of sludge formed during the process is less than the alternatives. Provides removal of unwanted pollutants in water with a single process
Electrocoagulation Application Areas
- Treatment of wastewater containing oil and grease
- Treatment of dye, textile and food industry wastewater
- Treatment of galvanized industrial wastewater and petrochemical industry wastewater
- Paper and pulp industry
- Restaurant wastewater treatment
- Treatment of leachate containing organic matter
- Pretreatment of membrane technologies such as reverse osmosis
- Preconditioning of boiler feed water with the removal of silica, hardness, AKM etc.
- Removal of kaolin, bentonite and very fine particles in water suspensions
- Sludge dewatering and heavy metal removal from wastewater
- Treatment of drinking and utility water
- Chlorine and bacteria removal before discharge or reuse of water
- Process washing and rinsing waters
- Biological oxygen demand (BOD), phosphate and nitrogen removal
- Removal of complex organics
- Breaking of the oil-water emulsion
Advantage of Electrocoagulation
- More effective than conventional coagulation in stabilizing and removing small colloidal particles.
- Less and more stable sludge is formed in electrocoagulation.
- Equipment is easy to use and operate.
- There is no need to add chemicals to the process. Therefore, it is easier to operate and maintain.
- The sludge formed exhibits a more dewaterable structure.
- The initial investment cost is quite low compared to alternative technologies.
- Many pollutants are removed with a single process.
Disadvantage of Electrocoagulation
- The electrode may oxidize as a result of the oxidation of dissolved substances in the wastewater.
- Electricity costs are high in many places (However, since the energy required to be used is very low, a high no cost).
- The suspended materials in the wastewater should have high conductivity.