An introduction to electrocoagulation

An Introduction to
Electrocoagulation
Christos Charisiadis

Contents
1. Introduction page 1
2. Process Description page 2
3. Factors affecting the efficiency of electrocoagulation process page 3
3.1 Electrode arrangement page 3
3.2 Type of power supply page 4
3.3 Current density page 4
3.4 Concentration of anions page 5
3.5 Effect of initial pH page 5
3.6 Electrode material page 5
4. Applications of electrocoagulation page 5
4.1 Water containing heavy metals page 6
4.2 Tannery and textile industry wastewater page 6
4.3 Food industry wastewater page 6
4.4 Paper industry wastewater page 6
4.5 Refinery wastewater page 6
4.6 Produced water page 6
5. Advantages and Disadvantages of Electrocoagulation page 7
5.1 Advantages page 7
5.2 Disadvantages page 7
5.3 Advantages of Electrocoagulation in Dissolved Metal Precipitation page 7
5.4 Advantages of Electrocoagulation in De-emulsification of Oil and Grease
page 8

6. Where does EC work well? page 8
7. Where EC doesn’t work? page 8
8. EC as a pretreatment to RO page 9
8.1 Electrocoagulation for the removal of water hardness and silica from Coal seam
gas (CSG) produced water. page 9
8.1.1 Results page 10
8.2 Removal of turbidity and suspended solids by electro-coagulation to improve feed
water quality of reverse osmosis plant. page 10
8.3 Assessment of hardness, microorganism and organic matter removal from
seawater by electrocoagulation as a pretreatment of desalination by reverse osmosis
page 11
9. Emerging usage of electrocoagulation technology for oil removal from wastewater
page 12
9.1 Characteristics of oily wastewater page 13
9.2 Results page 15
10. Electrocoagulation for the treatment of wastewater page 16
10.1 Continuous electrocoagulation process for the post-treatment of anaerobically
treated municipal wastewater page 16
10.2 The electrocoagulation pretreatment of biogas digestion slurry from swine farm
prior to nanofiltration concentration page 16
10.3 Can electrocoagulation process be an appropriate technology for phosphorus
removal from municipal wastewater? page 17
10.4 Removal of Cr ions from aqueous solution using batch electrocoagulation: Cr
removal mechanism and utilization rate of in situ generated metal ions page 18
REFERENCES page 20

P a g e | 1
Electrocoagulation Notes – Christos Charisiadis 2017
An introduction to Electrocoagulation
1. Introduction
Electro-coagulation became a proven and effective method for water treatment. It
represents a new alternative for treating water because of its high efficiency in
removing large number of pollutants. Natural and waste water contain dissolved
matters, suspended matters and colloidal particles. Colloidal particles are difficult to
remove since they are stable and this complicates water treatment.
In this process, the electro-dissolution of sacrificial anodes, usually made of aluminum
or iron, to the wastewater leads to the formation of hydrolysis products (hydroxo-
metal species) that are effective in the destabilization of pollutants. The
electrochemical reduction of water in the cathode produces hydrogen bubbles that
can promote a soft turbulence in the system and bond with the pollutants, decreasing
their relative specific weight. In addition, the generated hydrogen can be collected
and used as fuel to produce energy. This treatment has been successfully introduced
in removing suspended solids, dyes, heavy metals, arsenic, hardness, phosphate,
fluoride, pesticides and natural organic matter from wastewater.
For the use of electrocoagulation, there are some advantages such as requiring only
simple equipment, ease of operation, less treatment time, use of less or no chemicals,
and smaller amount of sludge.
2. Process Description
The basic EC unit typically consists of an electrolytic cell with an anode and cathode
metal electrodes connected externally to a DC power source and immersed in the
solution to be treated. Iron and aluminum electrodes are the most extensively used
metals for EC cells since these metals are available, non-toxic and proven to be
reliable. Although EC is considered to be quite similar to Chemical
Coagulation/Flocculation (CC/CF) in terms of the destabilization mechanism, it still
differs from CC/CF in other aspects such as the side reactions occurring simultaneously
at both electrodes. [5]

P a g e | 2
During electrocoagulation, the most important chemical reactions involve the
dissolution of metal cations at the anode and formation of hydroxyl ions and hydrogen
gas at the cathode Fig.1 [4],
M → Mn+ + ne-
2H2O(l) + 2e- → 2OH- + H2(g)
The current passes through a metal electrode, oxidizing the metal (M) to its cation
(Mn+). Simultaneously, water is reduced to hydrogen gas and the hydroxyl ion (OH−).
Electrocoagulation thus introduces metal cations in situ, using sacrificial anodes
(typically iron or aluminum) that need to be periodically replaced. The cations (Al3+,
Fe2+, etc.) destabilize colloidal particles by neutralizing charges. They also produce
monomeric and polymeric hydroxide complex species as coagulants.
Mn+
(aq) + nOH-
(aq) → M(OH)n(s)
These coagulants form amorphous metal hydroxide precipitates. Their high
adsorption properties impart strong affinity for dispersed particles and dissolved
pollutants. Thus the pollutants can be separated from aqueous phase by coagulation.

P a g e | 3
The hydrogen bubbles at cathode promote turbulence in the system and bond with
the pollutants, decreasing their relative specific weight. Consequently, they enhance
the separation process by flotation. [4]
3. Factors affecting the efficiency of electrocoagulation process [5]
3.1 Electrode arrangement
Regardless of the simplicity of the basic EC setup, it is not suitable for practical
wastewater treatment applications, as it requires huge electrode surface area to
overcome the metal dissociation rate; this is overcome by using monopolar or dipolar
electrode setups in series or parallel connections.

P a g e | 4
Results showed that monopolar connection gave much higher current efficiency with
lower operating cost compared to bipolar connection. However, bipolar connection
resulted in an almost complete removal of Cr3+ compared to 81.5% with monopolar
connection. The removal of fluoride from drinking water was better when bipolar
electrodes were used but the total operating cost of monopolar electrodes was much
less.
3.2 Type of power supply
DC power supply is typically used for electrocoagulation cells; however, using DC leads
to oxidation/consumption of the anode and a formation of an oxide layer on the
cathode known as cathode passivation. Passivation causes an increase in passive over
potential, which leads to higher power consumption; the passive layer also results in
a decreased flow of current between the two electrodes and decreases the efficiency
of EC.
3.3 Current density
Current density, which is the current per area of electrode, determines the amount of
metal ions released from the electrodes. In general, metal ion dissociation is directly
proportional to the applied current density. However, when too large current is used
there is high chance of wasting electrical energy in heating the water and even a
decrease in current efficiency expressed as the ratio of the current consumed to
produce a certain product to the total current consumption.

P a g e | 5
3.4 Concentration of anions
The presence of different anions has different effects on the destabilization properties
of metal ions. Sulfate ions are known to inhibit the corrosion/metal dissolution from
the electrodes and hence they decrease the destabilization of colloids and current
efficiency.
On the other hand, chloride and nitrate ions prevent the inhibition of sulfate ions by
breaking down the passive layer formed. The presence of chloride ions also
significantly reduces the adverse effect of sulfate ions, which lead to precipitation of
salts on the electrodes when the salt concentration is sufficiently high.
3.5 Effect of initial pH
pH is a key parameter when it comes to electrocoagulation as it affects the
conductivity of the solution, zeta potential and electrode dissolution. It is however
difficult to establish a clear relationship between the pH of the solution and the
efficiency of electrocoagulation since pH of the treated water changes during EC
process, therefore it is usually referred to the initial solution pH
3.6 Electrode material
Selecting the proper electrode material is critical since it determines the reactions that
would take place. As mentioned previously Al & Fe electrodes are most widely used
due to their proven reliability and availability, however, studies found that Fe (II) is a
weak coagulant if compared to Fe (III) due to its lower positive charge. A lower positive
charge indicates that the ion's ability to compress the electrical double
layer/destabilize colloids is weaker. In most of the studies, it is generally proven that
Al electrodes enhance the efficiency of removing pollutants better than Fe electrodes.
4. Applications of electrocoagulation [5]
This section presents an overview of the recent application of EC in the treatment of
different types of water and wastewater over the past few years. The review was
divided into six main categories namely:

P a g e | 6
4.1 Water containing heavy metals
Heavy metals are discharged from several industries and wastewater containing heavy
metals are challenging to treat as they are non-biodegradable and some metals are
toxic. Heavy metals: include cadmium, chromium, zinc, lead, mercury and arsenic.
4.2 Tannery and textile industry wastewater
Tannery and textile industry effluent is highly contaminated with organics, chromium
and different types of dyes. Chromium on its own is a major concern as it may oxidize
to Cr6+, which is carcinogenic and toxic. The presence of dyes also renders the water
quality very poor by preventing the passage of sun light; it is also known to be highly
stable, toxic and may resist chemical and biological degradation.
4.3 Food industry wastewater
Food industry consumes larger amounts of water for each ton of product compared
to other industries. Various contaminants are found in wastewater from food industry
depending on the sector but the general characteristics of wastewater are being highly
biodegradable and nontoxic with high suspended solids, COD and BOD. In the case of
meat processing industry, color, oil and grease are other concerns.
4.4 Paper industry wastewater
Paper industry consumes large amounts of water and the effluent is usually blackish
in color and highly contaminated with lignin, COD, BOD, organics, suspended solids
and arsenic.
4.5 Refinery wastewater
Includes wastewater generated from petroleum refineries and petrochemical
industries. It usually contains high level of aromatic and aliphatic hydrocarbons,
chemicals, dissolved solids, BOD and COD.
4.6 Produced water
Produced water is the largest by product by volume produced from oil and gas
industry. Although the composition of produced water depends on the nature of
produced hydrocarbon, the geological characteristics of the field, and the method of

P a g e | 7
extraction, it is usually very saline and contains various contaminants including
production chemicals, dispersed and dissolved oils, dissolved gases and different
minerals.
5. Advantages and Disadvantages of Electrocoagulation [5]
5.1 Advantages
a) Since no chemicals are needed, there is no chance of secondary pollution due
to high concentration of chemicals such as CC/CF
b) Gas bubbles produced from EC facilitates the removal of pollutants by floating
them on top of the solution so they can be easily collected.
c) EC is easily operated due to its simplicity of its equipment hence, complete
automation of the process is possible.
d) Wastewater treated by EC gives clear, colorless and odorless water.
e) Flocs formed by EC are much larger than CC/CF and more stable, hence they
are easily separated during filtration.
f) EC produces much less sludge volume than CC/CF and the sludge formed is
more stable and non-toxic.
g) Even the smallest colloidal particles are removed by EC since the applied
electric current makes collision faster and facilitates coagulation
5.2 Disadvantages
a) Regular replacement of sacrificial anode used in EC is necessary since the
anode dissolves into the solution.
b) Cathode passivation can occur which decreases the efficiency of the EC
process.
c) In some areas where electricity isn’t abundant, the operating cost of EC can be
expensive.
5.3 Advantages of Electrocoagulation in Dissolved Metal Precipitation [1]
a) EC does not add anions that compete for coagulation with the metal ions
b) The introduction geometry of the coagulant (Fe3+) enhances the chances of
precipitation

P a g e | 8
c) The reaction is more efficient that chemical precipitation resulting in less
sludge
d) No anions are left behind to increase osmotic loading on downstream
processes
5.4 Advantages of Electrocoagulation in De-emulsification of Oil and Grease [1]
a) EC offers an alternative to the use of metal salts/polymers/polyelectrolytes for
breaking stable emulsions and suspensions
b) The process destabilizes soluble organic pollutants and emulsified oils from
aqueous media by introducing highly charged polymeric metal hydroxide
species
c) These species neutralize the electrostatic charges on oil emulsions/droplets to
facilitate agglomeration/coagulation and separation from the aqueous phase
6. Where does EC work well? [1]
I. Higher Conductivity Applications (i.e., conductivity greater than 300 μS/cm)
II. Higher Suspended Solid Applications
a. Turbidity greater than 25NTU
b. TSS greater than 20 mg/L
III. Targeted Contaminates
a. Metals
b. Emulsified Oil & Grease
c. Total Suspended Solids
7. Where EC doesn’t work? [1]
I. Low Conductivity Applications (i.e., conductivity less than 300 μS/cm)
II. Low Suspended Solid Applications
a. Turbidity Less than 25 NTU
b. TSS Less than 20 mg/L
III. Non Polar and Monovalent Contaminates
a. Aqueous Salts (Na, K, Cl, F, etc.)
b. Non polar/charged particles

P a g e | 9
8. EC as a pretreatment to RO
Since feed water for reverse osmosis units must have specific properties and should
be nearly free from turbidity and suspended matters, it must be subjected to a special
treatment.
Conventional pretreatment of feed water to reverse osmosis plants consists of
physical treatment where water is passed through sand and carbon micro filters to
remove suspended matters and pollutants and prevent precipitation of
microorganisms and its growth on membranes. It also includes chemical treatment
where chemicals such as acids are added to control pH and prevent precipitation of
calcium and magnesium salts, and chlorine for disinfection and chemicals to remove
oxidant matters. The choice and arrangement of flow sheet for desalination plant
depends on the type of feed water and specifications of the water product. This also
depends on the technical and economic choice of the possible units for the required
treatment.
Electrocoagulation (EC) process can be used as an alternative pretreatment in order
to assess its applicability to replace the conventional pretreatments used to mitigate
membrane fouling prior to seawater desalination by reverse osmosis process.
8.1 Electrocoagulation for the removal of water hardness and silica from Coal seam
gas (CSG) produced water. [2]
Coal seam gas (CSG), also known as coal bed methane (CBM) is mostly comprised of
methane (CH4) and has become the subject of considerable commercial interest in
recent years.
The large volume of produced water associated with the production of CSG presents
a challenge to industry. The CSG water mainly contains sodium chloride (ranging from
200 to 10,000 mg/L), sodium bicarbonate and other trace elements.
Conventional pretreatment typically involves a coagulation, flocculation and particle
separation operation. Dissolved air flotation (DAF) and micro-sand ballasted
flocculation are the most commonly used particle separation processes in the CSG
industry.

P a g e | 10
EC provides an alternative to conventional chemical dosing, where an inorganic metal
salt such as aluminium chlorohydrate (ACH), polyaluminium chloride (PAC), alum,
ferric chloride or ferric sulphate is added as primary coagulants and settling provides
the path for pollutant removal. Literature suggests that EC is a promising technology
for the removal of silica, suspended particulates, and hardness in water.
8.1.1 Results
EC was able to achieve a 100% removal of calcium, strontium and barium, 98% silica
and 87% magnesium from the CSG water. The parameters used to achieve this
removal were a potential of 37.9 V and 60 sec of contact time, with aluminium
electrodes. Even though stainless steel electrodes did not produce the same removal
rate as aluminium electrodes, they still outperformed all of the chemical coagulants
tested in this experiment
8.2 Removal of turbidity and suspended solids by electro-coagulation to improve feed
water quality of reverse osmosis plant. [3]
Removal of total suspended solids TSS and turbidity from feed water of a reverse
osmosis unit by EC using iron electrodes is investigated. The effect of current density
and residence time were studied in an attempt to achieve a higher removal efficiency.
Water samples from well water with initial suspended solids TSS of 300 mg.L−1 and
turbidity of 150 NTU were prepared.
Experiments were carried out on two identical experimental RO units. The first was
fed with water treated by the conventional treatment while the other was fed with
water treated with addition of EC. All fouling indicators such as flow, pressure drop,
SDI show less fouling by addition of EC to the conventional pretreatment.
Electro coagulation at a current of 1.75A and 6min residence time gives 98% removal
efficiency of turbidity and 99% efficiency of removal of TSS. Addition of a Birm filter is
necessary to remove Fe(OH)3 precipitates formed. These alterations give a feed water
with a silt density index SDI less than 3%/min which is quite suitable for RO plants.

P a g e | 11
8.3 Assessment of hardness, microorganism and organic matter removal from
seawater by electrocoagulation as a pretreatment of desalination by reverse osmosis
[6]
The said study underscored the interest of electrocoagulation as an alternative
pretreatment prior to seawater desalination by reverse osmosis through interesting
results on DOC abatement and microorganism removal.
The pretreatment of seawater by electrocoagulation was conducted in a batch cell
with aluminum electrodes in the galvanostatic mode. On the basis of the experimental
results, the following conclusions may be drawn:
• The investigation of the removal of organic matter from seawater showed that
removal efficiency improved with higher current density and lower pH. A high removal
efficiency of seawater organic matter, comparable to that of a hybrid process, was
obtained. Electrocoagulation was able to achieve 57.5% DOC removal efficiency and
81% absorbance removal efficiency for a current density of 5.6 mA.cm−2 in the
optimum operating conditions of this work. It can be concluded that aromatic
compounds were removed more efficiently than the aliphatic compounds from
seawater by electrocoagulation, comparing DOC and UV254 removal efficiencies.
• The removal efficiency of total hardness from seawater by electrocoagulation to
avoid the problem of scaling on the reverse osmosis membrane was found to be weak
(abatement of total hardness around 10%). This also means that scaling on the
cathode was always limited in this work. However, scaling remains a possible
limitation of electrocoagulation which can be easily detected by an increase of cell
potential and power consumption. To prevent scaling, the literature advocates that it
would be better to use stainless steel as the cathode, but practical methods also
involve a limitation of the pH increase by limiting electrolysis time or applying current
reversal (switching anode and cathode electrically) when both electrodes are made of
aluminum.
• When electrocoagulation was used as a disinfection process, a high disinfection
efficiency was obtained with a nearly complete removal of microbial cells. Prior to
seawater desalination, electrocoagulation may be an efficient alternative to

P a g e | 12
chlorination, as the latter presents many drawbacks, such as its ineffectiveness to
prevent biofouling and its reactivity with organic compounds that could lead to the
formation of carcinogenic organic byproducts including trihalomethanes, haloacetic
acids and other toxic disinfection by-products. In addition, chlorination of feed
seawater can provoke the fragmentation of humic substances into smaller organic
fragments easily assimilable by microorganisms, thereby causing biofouling.
9. Emerging usage of electrocoagulation technology for oil removal from
wastewater [4]
Oil removal from wastewater is regarded to be a main challenge in treatment
practices. Dispersed oil droplets usually have high surface charges, resulting in the
stability of oil-in-water system. This is especially true when emulsified oil exists.
Emulsion generation and stabilization are usually achieved by mechanical agitation
and addition of emulsifying agents. Although qualitative and quantitative
compositions of oily wastes are different in many effluent sources, significant part of
oil is always present in the emulsified form. Some available technologies such as
gravity separation, cyclone separation, chemical precipitation, sorption, membrane
filtration and chemical oxidation have been used for oil removal.
Although many advantages of these technologies have been reported, some specific
disadvantages associated with these approaches (i.e. low efficiency, long processing
time, secondary pollution and high costs) exist in treatment applications. The
efficiencies of many methods for treatment of oily wastewater remain unsatisfactory.
An alternative to available oil removal technologies is electrocoagulation. In this
process, the electro-dissolution of sacrificial anodes, usually made of aluminum or
iron, to the wastewater leads to the formation of hydrolysis products (hydroxo-metal
species) that are effective in the destabilization of pollutants. The electrochemical
reduction of water in the cathode produces hydrogen bubbles that can promote a soft
turbulence in the system and bond with the pollutants, decreasing their relative
specific weight. In addition, the generated hydrogen can be collected and used as fuel
to produce energy. This treatment has been successfully introduced in removing

P a g e | 13
suspended solids, dyes, heavy metals, arsenic, hardness, phosphate, fluoride,
pesticides and natural organic matter from wastewater.
For the use of electrocoagulation, there are some advantages such as requiring only
simple equipment, ease of operation, less treatment time, use of less or no chemicals,
and smaller amount of sludge.
9.1 Characteristics of oily wastewater
The characteristics of oily wastewater depend on the nature of relevant production,
operation, and chemicals used in processing facilities. The compositions of oily
wastewater from different sources can vary by order of magnitude. Constituents
typically associated with oily wastewater include: (i) Dispersed oil. Dispersed oil
consists of small droplets suspended in the aqueous phase. They may also reach the
bottom or rise to the surface of water body. (ii) Dissolved or soluble organic
components, such as organic acids, PAHs, phenols, and volatiles. These hydrocarbons
can often lead to additional toxicity of oily wastewater. (iii) Processing chemicals, such
as biocides, reverse emulsion breakers, and corrosion inhibitors. Some of these
chemicals are lethal at levels as low as 0.1 mg/L. Corrosion inhibitors can make oil-
water separation less efficient due to the formation of more stable emulsions. (iv)
Solids, such as precipitated solids, sand and silt, clays, corrosion products, and other
suspended solids derived from production and operation. The fine-grained solids can
reduce the efficiency of oil-water separators, leading to the exceedance of oil and
grease limit in discharged wastewater. (v) Bacteria. Bacteria can clog equipment and
pipelines. They can also form difficult-to-break emulsions and hydrogen sulfides which
are corrosive. (vi) Dissolved formation minerals, such as heavy metals, naturally
occurring radioactive materials, etc. Besides toxicity, these may cause production
problems. (vii) Salinity. Environmental impacts of salts in oily wastewater exist in all
regions where oil and gas are produced.

P a g e | 14

P a g e | 15
9.2 Results
Each oil removal approach has its own advantages and disadvantages. This is also true
for electrocoagulation. To meet ever-stricter environmental regulations,
electrocoagulation can be used with other treatment techniques as either pre-
treatment or post-treatment process. Choice of the best combination can be
determined based on oily water characteristics, cost-effectiveness, space availability,
and reuse and discharge plans. In such a way, the advantages of various methods can
be maximized to avoid their limitations. The higher percentages of oil-containing
water can be recovered and utilized for reducing operating costs and achieving
environmental sustainability.

P a g e | 16
10. Electrocoagulation for the treatment of wastewater
10.1 Continuous electrocoagulation process for the post-treatment of anaerobically
treated municipal wastewater [8]
The potential of continuous electrocoagulation (EC) process with aluminium
electrodes for the post-treatment of upflow anaerobic sludge blanket (UASB) reactor-
treated municipal wastewater was investigated. In order to optimize the performance,
influence of three parameters affecting EC, namely, chemical oxygen demand (COD),
current density (CD) and residence time in the reactor was studied using response
surface methodology (RSM) with Box–Behnken design (BBD) employing real UASB
reactor effluent. The results of the modelling study gave the following optimum
conditions: influent COD concentration 274 mg/L, CD 2mA/cm2 and residence time
5min; and predicted effluent COD, phosphate and turbidity values of 87 mg/L, 0.59
mg/L, and 12.6 NTU, respectively. Confirmatory tests at these optimum conditions
gave 90 mg/L effluent COD, 0.57 mg/L effluent phosphate and 15.2 NTU effluent
turbidity, which were in close agreement with the predicted results. At optimum
conditions, high removals of BOD and suspended solids were also observed, with
effluent BOD and suspended solids concentration of 34 mg/L and 29mg/L,
respectively. High total coliform and faecal coliform removals of 99.81% and 99.86%,
respectively, were also obtained at these conditions. The study thus suggests EC as an
attractive post-treatment option for UASB reactor-treated municipal wastewater. At
present market prices, the operating costs of the process were calculated at ∼0.07
US$ per m3 of effluent treated.
10.2 The electrocoagulation pretreatment of biogas digestion slurry from swine farm
prior to nanofiltration concentration [9]
The relationship between the crucial parameters and the turbidity removal from the
biogas digestion slurry by EC was investigated in this study, and the optimal
combination of the key operating parameters was determined using RSM, achieving
high turbidity removal efficiency at an acceptable electricity cost. The effectiveness of
EC pretreatment for decreasing the flux loss in the NF system as well as the running
cost of EC was also analyzed.

P a g e | 17
The main conclusions could be drawn as follows: Except for the electrode gap, current
density, reaction time and A/V all had a significant effect on the turbidity removal from
biogas digestion slurry. Among the operating parameters of current density, reaction
time and A/V, current density had the most significant effect on turbidity removal and
electric energy consumption of EC, and the optimal combination for a high turbidity
removal (65.6%) at low electric energy (0.73Wh.L-1) consumption was determine by
RSM at current density of 35.7 A.m-2, reaction time of 24 min, and A/V of 20.7 m2.m-3.
RSM was a suitable method to optimize the operating conditions and maximize the
turbidity removal rate while keeping the electric energy consumption to minimal.
Furthermore, the EC was capable of alleviating NF membrane fouling by 22.2% in
terms of reducing membrane flux loss for treating biogas digestion slurry. The running
cost of EC pretreatment for biogas digestion slurry was estimated to be 0.29 US$
RMB.m-3 based on the electrical energy use and the loss of aluminum anode. In
summary, it is feasible to use EC as a pretreatment unit for NF concentration system
treating the biogas digestion slurry, given an additional benefit of mitigating
membrane fouling. However, the effect of temperature on the EC process, and the
safety of the sludge generated from the EC system need to be further studied.
10.3 Can electrocoagulation process be an appropriate technology for phosphorus
removal from municipal wastewater? [7]

P a g e | 18
This study case evaluated a novel pilot scale electrocoagulation (EC) system for
improving total phosphorus (TP) removal from municipal wastewater. This EC system
was operated in continuous and batch operating mode under differing conditions (e.g.
flow rate, initial concentration, electrolysis time, conductivity, voltage) to evaluate
correlative phosphorus and electrical energy consumption. The results demonstrated
that the EC system could effectively remove phosphorus to meet current stringent
discharge standards of less than 0.2mg/L within 2 to 5min. This target was achieved in
all ranges of initial TP concentrations studied. It was also found that an increase in
conductivity of solution, voltages, or electrolysis time, correlated with improved TP
removal efficiency and reduced specific energy consumption. Based on these results,
some key economic considerations, such as operating costs, cost-effectiveness,
product manufacturing feasibility, facility design and retrofitting, and program
implementation are also discussed. This EC process can conclusively be highly efficient
in a relatively simple, easily managed, and cost-effective for wastewater treatment
system.
10.4 Removal of Cr ions from aqueous solution using batch electrocoagulation: Cr
removal mechanism and utilization rate of in situ generated metal ions [10]
The removal mechanism of batch electrocoagulation (EC) process for removing Cr ions
was investigated. The influence of operation parameters on removal mechanisms was
discussed. The utilization rate of in situ electro-generated Fe ions in the sludge was
introduced to investigate the removal mechanism and optimize the EC process. The
Fe elements’ utilization rate resulting from the specific adsorption is much higher than
that resulting from precipitation and co-precipitation. The initial pH determines which
removal mechanism dominates the Cr removal. At neutral initial pH condition, Cr ions
are mainly removed by flocs’ surface complexation reaction (specific adsorption). The
utilization rate of Fe ions at neutral pH condition reaches its maximum and is higher
than that at other pH conditions. The influence of electrode material on EC
performance was investigated on the basis of utilization rate of Fe ions. For EC with
Fe/Al electrode combination, although direct dissolution of Al ion from Al electrodes
will improve the Cr(VI) removal efficiency, the utilization rate of generated metal ions
is much lower, when compared with EC with Fe/Fe electrode. The utilization rate of in

P a g e | 19
situ electro-generated metal ions could be considered as a new index to evaluate EC
performances.

P a g e | 20
REFERENCES
1. BANFF; Electrocoagulation: An Innovative Approach for Recycling Produced Water
and as a Pre-Treatment to Reverse Osmosis for Emulsified Oils, Heavy Metals and
Other Constituents in the Oil and Gas Industry
2. ELECTROCOAGULATION AS A PRE - TREATMENT STAGE TO REVERSE OSMOSIS
UNITS (2014)
3. Removal of turbidity and suspended solids by electro-coagulation to improve feed
water quality of reverse osmosis plant (2011)
4. Emerging usage of electrocoagulation technology for oil removal from
wastewater: A review (2017)
5. A comprehensive review of electrocoagulation for water treatment: Potentials
and challenges (2016)
6. Assessment of hardness, microorganism and organic matter removal from
seawater by electrocoagulation as a pretreatment of desalination by reverse
osmosis (2016)
7. Can electrocoagulation process be an appropriate technology for phosphorus
removal from municipal wastewater? (2016)
8. Continuous electrocoagulation process for the post-treatment of anaerobically
treated municipal wastewater (2016)
9. The electrocoagulation pretreatment of biogas digestion slurry from swine farm
prior to nanofiltration concentration (2015)
10. Removal of Cr ions from aqueous solution using batch electrocoagulation: Cr
removal mechanism and utilization rate of in situ generated metal ions (2016)

An introduction to electrocoagulation

Recomendados

Recomendados

Más contenido relacionado

La actualidad más candente

La actualidad más candente (20)

Similar a An introduction to electrocoagulation

Similar a An introduction to electrocoagulation (20)

Más de Christos Charisiadis

Más de Christos Charisiadis (9)

Último

Último (20)

An introduction to electrocoagulation