WasteWater Treatment uses various technology and process to purify water from various impurities, among many those electrocoagulation process is the most effective one. Electrocoagulation process removes metals, colloidal solids and particles and soluble inorganic pollutants from aqueous media by introducing highly charged polymeric metal hydroxide species. Electrocoagulation process has become one of the affordable wastewater treatment processes around the world by reducing electricity consumption and miniaturization of the needed power supplies. Electrocoagulation process as found its applications in various water treatment process such as Ground Water Cleanup, Surface Water Cleanup, Process Rinse Water and Wash Water, Sewage Treatment, Cooling Towers, Water Pretreatment.

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2.  One of the basic requirements of a human being is
Water. Globalization, un-controlled population and
other factors are creating shortage of pure water and
the issue is a concern for many countries.
 Thus, it becomes imperative to think about water
purification using effective and inexpensive techniques
and its reusability.
 A wide range of wastewater treatments are currently
known to people. With the recent technology
development in electrochemical field, a new technique
has been introduced in the industry, named as
electrocoagulation. The main objective of this article is
focusing on electrocoagulation process methodology
and its applications.

3.  The classical physico-chemical treatment processes that are used for the
wastewater treatment is filtration, air stripping, ion-exchange, chemical
precipitation, chemical oxidation, carbon adsorption, ultrafiltration,
reverse osmosis, electrodialysis, volatilization and gas stripping. One of
the advanced electrochemical technology based technique is the
electrocoagulation process.
 Electrocoagulation (EC), the passing of electric current through water, has
proven very effective in the removal of contaminants from water.
Electrocoagulation systems have been in existence for many years
(Dietrich, patented, 1906) using a variety of anode and cathode
geometries, including plates, balls, fluidized bed spheres, wire mesh, rods
and tubes.
 In the past few decades it has been used for the treatment for the water
containing foodstuff wastes, oil wastes, dyes, suspended particles,
chemical and mechanical polishing waste, organic matter from landfill
leachates, defluorination of water, synthetic detergent effluents, mine
wastes and heavy metal-containing solution.
 EC has become one of the affordable wastewater treatment processes
around the world by reducing electricity consumption and
miniaturization of the needed power supplies.

4.  EC offers an alternative to the use of metal salts or polymers and
polyelectrolyte addition for breaking stable emulsions and suspensions.
EC removes metals, colloidal solids and particles and soluble inorganic
pollutants from aqueous media by introducing highly charged polymeric
metal hydroxide species.
 EC uses a proprietary treatment chamber and electricity to treat a wide
range of differing waste streams containing heavy metals, virus, bacteria,
pesticides, arsenic, MTBE, cyanide, Biochemical oxygen demand (BOD),
Total dissolved solids (TDS), and Total suspended solids (TSS). It is used
to treat municipal, industrial and commercial wastewater.
 EC reactor is made up of an electrolytic cell with one anode and one
cathode. EC system essentially consists of pairs of conductive metal plates
in parallel, which act as monopolar electrodes. The requirements to
operate EC are
 Direct current power source
 Resistance Box
 Multimeter

6.  The conductive metal plates are commonly known as ―sacrificial electrodes.‖ The
sacrificial anode lowers the dissolution potential of the anode and minimizes the
passivation of the cathode. The sacrificial anodes and cathodes can be of the same or of
different materials.
 The monopolar electrodes with cells are arranged in series. In series cell arrangement, a
higher potential difference is required for a given current to flow because the cells
connected in series have higher resistance. During electrolysis, the positive side
undergoes anodic reactions, while on the negative side, cathodic reactions are
encountered. Coagulation process will initiated by neutralizing the charges of the
particles by released ions.
 The released ions remove undesirable contaminants either by chemical reaction and
precipitation, or by causing the colloidal materials to coalesce, which can then be
removed by flotation. Water containing colloidal particulates, oils, or other contaminants
move through the applied electric field, there may be ionization, electrolysis, hydrolysis,
and free-radical formation which can alter the physical and chemical properties of water
and contaminants. The reactive and excited state causes contaminants to be released
from the water and destroyed or made less soluble.
 Within the electrocoagulation reactor, several distinct electrochemical reactions are
produced independently

7.  Seeding - It is resulting from the anode reduction of metal ions that
become new centers for larger, stable, insoluble complexes that
precipitate as complex metal ions.
 Emulsion Breaking – It is resulting from the oxygen and hydrogen ions
that bond into the water receptor sites of oil molecules creating a water-
insoluble complex separating water from oil, driller's mud, dyes, inks, etc.
 Halogen Complexing - as the metal ions bind themselves to chlorines in a
chlorinated hydrocarbon molecule resulting in a large insoluble complex
separating water from pesticides, herbicides, chlorinated PCBs, etc.
 Bleaching by the oxygen ions produced in the reaction chamber oxidizes
dyes, cyanides, bacteria, viruses, biohazards, etc. Electron Flooding of the
water eliminates the polar effect of the water complex, allowing colloidal
materials to precipitate and the increase of electrons creates an osmotic
pressure that ruptures bacteria, cysts, and viruses.
 Oxidation Reduction reactions are forced to their natural end point
within the reaction tank which speeds up the natural process of nature
that occurs in wet chemistry.

8.  Removes heavy metals as oxides that pass
Toxicity characteristic leaching procedure
(TCLP)
 Removes suspended and colloidal solids
 Breaks oil emulsions in water
 Removes fats, oil, and grease
 Removes complex organics
 Destroys and removes bacteria, viruses and
cysts

9.  Supplied as a skid mounted unit, fully
assembled for inlet/outlet and backwash
connections
 Low operating costs
 Low power requirements
 Minimal chemical additions
 Low maintenance
 Sludge minimization

10.  1. The ‗sacrificial electrodes‘ are dissolved into
wastewater streams as a result of oxidation,
and need to be regularly replaced.
2. The use of electricity may be expensive in
many places.
3. An impermeable oxide film may be formed
on the cathode leading to loss of efficiency of
the EC unit.
4. High conductivity of the wastewater
suspension is required.
5. Gelatinous hydroxide may tend to solubilize
in some cases.

11.  Ground Water Cleanup
 Surface Water Cleanup
 Process Rinse Water and Wash Water
 Sewage Treatment
 Cooling Towers
 Water Pretreatment

12.  Ground Water Cleanup
 EC is extremely effective in the removal of naturally occurring salts in
well water, as well as the separation of iron, magnesium, calcium, metals,
nitrates and sulfur. EC is also well suited for the reclamation of ground
water that has been contaminated with heavy metals, high molecular
weight hydrocarbons and Halogenated hydrocarbons.
 Surface Water Cleanup
 EC is used to remove bacteria, viruses and cysts from surface water,
thereby rendering contaminated waste streams into potable water. EC is
particularly effective in the removal of life threatening contaminants such
as giardia and cryptosporidium.
 Process Rinse Water and Wash Water
 EC routinely treats process and rinse water from the electroplating,
computer board manufactures, textile industry, paint rinse water, steel
production, mining industry, automotive industry, equipment repair
industry, stack wash water, and pulp and paper. In most cases, the
treated water can be recycled and reused.

13.  Sewage Treatment
 EC has proven effective in treating sewage water,
sewage sludge concentrations, and sewage sludge
metal fixation sufficiently to enable land application.
 Cooling Towers
 EC is used to pre-treat water entering towers as well as
blow down water to remove algae, suspended solids,
calcium, and magnesium buildup, thereby eliminating
costly replacement water.
 Water Pretreatment
 Water pretreatment with EC has proven effective in
removing bacteria, silica and TSS prior to subsequent
polishing with reverse osmosis, ultra filtration,
nanofiltration, and photocatalytics.

14.  Electrocoagulation has a wide variety of wastewater
treatment capabilities. It is the process of destabilizing
suspended, emulsified or dissolved contaminants in
aqueous medium by introducing a minimal amount of
electrical current. It thereby reduces additional costs
involved for the process. It even replaces traditional
treatment process such as filtration, chemical
treatment, which have proved to be less effective and
expensive processes. Considering the benefits, EC
process helps removal of TSS by 95-99 per cent; BOD
by 50-98 per cent and Bacteria by 95-99 per cent. This
suggests that the technique is effective and reliable for
a wide variety of future applications, which in turn will
give hope for purified water for all.

15.  1] © From Universal Systems, Inc website -
http://www.universalsystemsinc.net/electrocoagulation.ht
ml
 [2] © From Natural Systems, website - http://www.n-
systems.net/electrocoagulation.htm
 [3] © From Powell Water Systems Inc, website -
http://www.powellwater.com/Data/Technical%20Manual.
pdf
 Image reference
 Fig. 1) M. Yousuf A. Mollah, Robert Schennach, Jose R.
Parga, David L. Cocke, Electrocoagulation (EC)—science
and applications, Available from -
http://dl.mozh.org/up/Electrocoagulation
 To contact the author mail: articles@worldofchemicals.com
 © WOC Article