Electrocoagulation Water Treatment

January 26, 2021
January 26, 2021 Marketing

What is Electrocoagulation

Electrocoagulation (EC) is an emerging technology in water and wastewater treatment. It combines the advantages of coagulation, flotation, and electrochemistry. It is an electrochemical process that uses electric current to remove suspended, emulsified, or dissolved pollutants from water. Electrochemical wastewater treatment technology has begun to regain attention because it is an environmentally friendly option that can produce the least sludge, does not require chemical additives, and the smallest footprint, without affecting the water quality after treatment.

 

How Electrocoagulation Works

electrocoagulation dissolution        electrocoagulation coagulation        electrocoagulation flocculation

  • H2 bubble generation, with 0,001 to 0,1 µm diameter increasing sludge flotation process
  • Electrochemical Process with electron transfer
  • Electrode + (oxidized anode) and cathode – (reduced)

 

Advantages of Electrocoagulation Water Treatment

The main advantage of electrocoagulation water treatment over other technologies like chemical coagulation/flocculation CC/CF is that coagulation/flocculation uses chemical coagulants/flocculants such as metal salts or polyelectrolytes. In electrocoagulation, the coagulants are generated in situ by the electrolytic oxidation of an appropriate anode material which results in much less sludge generation.

Compared with CC/CF and other conventional water treatment methods, another major advantage of electrocoagulation water treatment is that it can treat oily water, where the presence of electric current can help the electrocoagulation of oil droplets. With several applications, the technology can be used in water containing heavy metals, tannery, and textile industry water treatment, food industry wastewater, paper industry wastewater, refinery wastewater, or produced wastewater from the oil and gas industry.

Advantages of VentilAQUA system regarding other possible Electrocoagulation setups and technologies

  • Nonbinding customer to electrode replacement
  • Very low cost for electrodes – cheap steel sheets – can even use nonconforming metal sheets or scrap metal sheets
  • Easy logistics and easy to find electrodes, worldwide
  • Low current and electrical density (8v vs. 120 V; 20 kW vs. 120 kW installed) – fewer risks, fewer security procedures, longer lifetime cycles
  • Space between electrodes avoids blockage problems from sludges and metal oxidized materials
  • Integrated cleaning device for electrodes, keeping them active and avoiding passivation

 

Electrocoagulation Water Treatment

As a pioneer in compact wastewater chemical plant technology, VentilAQUA developed unique Compact Units for physical-chemical wastewater treatment solutions, which have proven to be an effective solution in every application around the world.

Industrial wastewaters coming from different sources can be easily treated or pre-treated in a simple and compact system, to be able to comply with sewage discharge regulations or environment discharge limits. Furthermore, treated waters can be recovered through different industrial processes.

The ecological and economic advantages of the compact systems, open up new possibilities for many users to treat their industrial wastewaters, simply, with low investment, cost-effective, in an easy-friendly structure, with low space requirements, small footprint, etc.

Application and target audience

  • Recalcitrant and difficult molecules removal
  • Color removal
  • Detergents/Tensioactive removal, emulsions breakdown
  • Improved reduction of COD and BOD
  • Increasing biodegradability of tough effluents to improve downstream treatment efficiencies
  • Either first step or tertiary treatment easy add-on to existing plants
  • New and future standards and requirements from EU and other authorities related to rejecting limits

 

Industrial Electrocoagulation Units

Automotive Industry

The Automotive/Aeronautic/Metal industry (cars, trucks, planes, heavy machinery, components) faces increasing environmental requirements, especially on COD, metal removal, and special molecules removal. Often residual metal contents, residual hydrocarbon or oil levels, or surfactant content are a problem that traditional chemical or biological treatment plants cannot address and solve. Often a good and effective treatment plant can no longer comply with new requirements, coming either from authorities or even from internal goals and strategy. Most often, operating costs for existing plants are extremely high.

electrocoagulation water treatment automotive

Introducing advanced oxidation systems like electrocoagulation to these operations, is the key to solve these problems, either along with new treatment plants or just revamping/ retrofitting existing ones. Very short paybacks on investment with these revamping are quite common. Many companies use very expensive final or tertiary treatment procedures, like activated carbon adsorption, to try to solve these problems, most of the time unsuccessfully at a very high cost.

VentilAQUA’s AOP solutions with electrocoagulation show the way to metal, oils, and emulsion removal. No more huge chemical dosage, no more huge activated carbon adding, no more pH Control up and down is required.

Metal removal is easy and fast forward with electrocoagulation water treatment. Oils and emulsion removal also. No more huge chemical dosage, no more huge activated carbon adding, no more pH control up and down is required.

Inlet parameters:
COD – 40.000 mg/j
TSS – 500 mg/l
Flow – 2000 L/h
Outlet parameters:
COD reduction between
90 and 97%
BOD reduction between
89 and 99%
O&G below 5 ppm
Boro below 0,3 ppm
Cu below 0,4 ppm
Pb below 0.01 ppm
Sn below 0.01 ppm
Fluorine below 0.01 ppm
Detergents below 1 ppm

 

Chemical & Pharma Industry

In recent years, the number, variety, and composition of synthetic chemical compounds have increased tremendously. Their use has influenced every aspect of modern life. A particularly widespread group of chemical compounds are phenolic resins (phenol-formaldehyde resins or bakelite). They have been reported to have high stability and high environmental toxicity.

Additionally, carcinogenic properties can damage human health seriously. The phenol-formaldehyde resin producing industries generate wastewater with a high concentration of organic matter. Such wastewaters are difficult to be treated by biological processes when the phenol is present at high a concentration. The reason is that it causes inhibition to the normal function of the microbial population.

electrocoagulation water treatment chemical & pharma

The key to overcoming these problems lies in oxidative pre-treatment, such as adding electrocoagulation process before a biological one. Electrocoagulation water treatment is an electro-chemical process that removes suspended, emulsified or dissolved contaminants from water using an electric flow of charge. It generates a direct flow of charge to free into the liquid the metal ions from sacrificial anodes that will remove undesirable contaminants.

These technologies combined allowed for the total removal of formaldehyde and consequently, COD and BOD with a 99% removal. With these results, operating costs decreased a lot because all wastewater was being directed to a hazardous waste management company that charged for the transportation and treatment of the effluent. Such advantages in the cost of operation and construction will have a considerable impact on the economic balance of the project, in global terms.

Inlet parameters:
COD – 200.000 mg/L
Formaldehyde – 120.000 mg/L
Outlet parameters:
COD – 1000 mg/L
Formaldehyde – <120 mg/L

 

Food Industry

The day-to-day demands of Western societies have profoundly changed the eating habits of populations. The need to devote little of our time to daily meals, generated a change in demand for pre-cooked meals, causing this industry to grow significantly. On the other hand, this change causes an environmental impact, as the resulting waters from this grouping industrial activity are being discharged in city sewage networks with high pollutants, causing therefore extra stress to the already overloaded streams. Discharges of high amounts of grease, organic loads, suspended solids, and other pollutants, will affect the downstream treatment plants, besides not complying with the majority of reject limits for wastewaters established by local authorities.

food industry electrocoagulation

Replacing standard grease traps with advanced oxidation chemical treatment units together with flotation devices (DAF), we managed to perform a proper chemical treatment to the wastewaters, remove all solids, fats, and greases, avoid bad odors, besides reducing drastically its organic loads, allowing these waters to be discharged into the sewage lines, complying with discharge limits and reducing dramatically the discharge fees.

VentilAQUA brought to this process an advanced oxidation technology, using electricity, called electrocoagulation and electro-oxidation, which allows a more intense and efficient organic matter removal without chemicals, managing to reduce contamination to very low levels. Electrocoagulation also contains a special feature to allow the system to auto-adjust towards the load variations and maximize automation features of the system.

The results were fully compliant with environmental regulations, the reduction of the resulting waste, and a high level of system automation, therefore reducing operational work.

Data Results:

90% COD reduction

99% TSS reduction

90% O&G reduction

 

Shopping Malls & Industrial Kitchens

One of the most critical sources of environmental problems in any shopping center or mall is the food court, with its greasy wastewaters. From a long-term experience and survey, the majority of malls and shopping centers have serious compliance problems with waters coming from grease traps.

Grease traps are designed to retain wastewaters for a period of time, generating bad odors and increasing organic loads that will affect the downstream treatment plant, besides not complying with the majority of reject limits for wastewaters established by local authorities.

Replacing standard or more sophisticated (although with limited performance) grease traps by chemical treatment units, with flotation devices (DAF), we manage to perform a proper chemical treatment to the wastewaters, remove all solids, fats, and greases, avoid bad odors, besides reducing drastically its organic loads, preparing these waters for final disinfection and filtration which will allow them to be reintroduced into an internal feed line to flush waters and irrigation.

electrocoagulation water treatment shopping malls

VentilAQUA brought to this process an advanced oxidation technology, using electricity, called electrocoagulation and electro-oxidation, which allows a more intense and efficient organic matter removal without chemicals, managing to reduce contamination to very low levels and allowing to use of common multimedia filters with a longer lifetime and to reuse these waters.

Under 1 year payback time with water consumption reduction, about 90% of food court wastewaters are recovered into flushing toilets, thus reducing dramatically water consumption in toilet rooms. Elimination of complex removal and trucking of liquid wastes and greases, highly loaded, and consequent extremely high cost.

Data Results:

90% BOD reduction

50% reduction on flushing waters

ROI under 1 year

 

Textile Dyeing Industry

Textile dying operations face paramount challenges around the world. Known as huge water consumers, textile plants have to adapt to these new demands and requirements from authorities, from society, which no longer accepts to have to deal with their environmental footprints. Thus, changing existing plants or building new ones are the most urgent actions to be taken. But in both cases, care needs to be taken in choosing the right solutions to achieve the right goals, from a simple reject into municipal sewer systems or to comply with the most stringent demands like ZLD (Zero Liquid Discharge), more and more popular amongst large Textile producing countries. In all these alternatives, new technologies have to be introduced, as the traditional approach is no longer compatible with these demands and requirements.

electrocoagulation water treatment textile

Even though many plants use chemical and biological water treatment systems, compliance issues, difficulty in reusing treated water, and operating costs are still a struggle. So, the key to overcoming these problems lies in oxidative pre-treatment, such as adding an electrocoagulation process to a biological one. In fact, such technology involves a powerful oxidation process that removes detergents and surfactants, solving Chemical Oxygen Demand (COD) problems, removing color, decreasing salinity, and preparing effluent to recovery and reuse plants.

Electrocoagulation really is the future for water treatment in the textile industry, in particular for plants that present high salinity levels, increased reject water volumes, alarming operating costs, and low-efficiency indicators.

These technologies combined allowed for the total removal of color, surfactants, and, consequently, COD and BOD. At the end of the day, clean and clear water comes out of our client’s plants, at a flow rate of 6 m3/h. Also, at stake now presents lower operating costs and decreased sludge production. Efficiency that outperforms a lot of a standard chemical process.

Data Results

Total solids removal
Total color removal
Tensoactives below 2ppm
Final COD below 120 ppm

 

Electrocoagulation Process – Laboratory Demonstration

This video is a short demonstration of an electrocoagulation water treatment process. It contains a real industrial effluent, loaded with dyes, detergents, and oils. You’ll watch a very rapid reaction, with no added chemicals, besides a tiny drop of anionic flocculant to increase sludge size for solid/water separation. Very low current, very short contact time. End with clear and turbidity-free water, with easy to separate sludges.

 

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