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  1. The Differences Between Coagulation and Flocculation in Water Treatment

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    Coagulation and flocculation are two methods used to increase particle size and enhance filtration efficiency. Regardless of the size of the system, coagulation and flocculation are typically the initial steps in water and wastewater treatment.

    At their most basic, coagulation and flocculation involve the process of adding positively charged chemicals to the water. These chemicals neutralize negatively charged dirt and other dissolved particles in the water, which causes them to bind with the chemicals to form larger, more easily filtered particles, called floc. Although both processes have the same end goal and are often used together, there are fundamental differences between the two.


    Coagulation in water treatment uses specialized chemicals to encourage fine particles to clump together. These chemicals, known as coagulants, create an electronic charge that causes the particles to cluster into larger groupings that make them easier to filter.

    Types of Coagulants

    Coagulants used in water filtration applications are typically either aluminum or iron-based.

    Common aluminum coagulants include:

    • Aluminum sulfate
    • Aluminum chloride
    • Sodium aluminate

    Common iron-based coagulants include:

    • Ferrous sulfate
    • Ferric sulfate
    • Ferric chloride
    • Ferric chloride sulfate

    In addition to the above, water filtration facilities may also use hydrated lime and magnesium carbonate.

    Coagulation Process

    The coagulation process uses coagulant chemicals to destabilize negatively charged particles in the water, such as dirt, clay, soil, and other organic particles. Since the negative charge is what keeps these dispersed particles from coalescing, neutralizing that charge allows those solids to stick together, creating submicroscopic clumps of particles known as microflocs.

    To facilitate the collision of particles for optimal coagulation, the liquid must be mixed rapidly. This quickly disperses the coagulant into the water, while facilitating the formation of clumps by forcing more of the neutralized particles to collide. To ensure optimal coagulation, it is recommended that the water be agitated at high speed for 1-3 minutes after the coagulant has been added. Once the coagulation process is complete, the water is often treated using flocculation.


    While coagulation helps to encourage particles to combine into larger, more easily filtered clumps, the resultant microflocs are still far too small for standard filtration systems to clear. Flocculation takes the coagulation process a step further by gently agitating the microfloc-containing water at varying speeds to encourage more particle adhesion.

    Flocculation Process

    The flocculation process takes treated water from the coagulation stage and mixes it slowly to increase the collision rate between suspended microfloc particles. As they collide, the microflocs bond further to create larger flocs, which are visible to the naked eye.

    Through additional mixing, these flocs continue to grow and bond with other organic or inorganic polymers which may be produced by the coagulant or coagulant aids added during this step. With these polymers, the flocs form into macroflocs, which become increasingly heavy. The added weight allows the macroflocs to settle at the bottom, where they can be easily removed.

    Flocculation Variants

    The amount of flocculation induced during the mixing process differs based on the mixing speed and the amount of time for which the material is mixed. There are a variety of mechanisms used to control flocculation speed and particle aggregation to produce the desired particle size and consistency. While rotating blades are the most common flocculation equipment for large-scale water treatment facilities, other methods include granular media beds, diffused air, baffled chambers, and spiral flow chambers.

    Expert Water Treatment by Reynolds Culligan

    Since 1948, Reynolds Culligan has been the only Mid Atlantic industrial water treatment provider who offers single-source, comprehensive water treatment solutions for virtually every industry. To learn more about our extensive selection of water treatment technology systems for industrial, commercial, and residential applications, contact Reynolds Culligan today.

  2. What is the Best Water Purification System?

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    The water purification process removes harmful contaminants and unwanted material from a source of water. Contaminants may include hazardous chemical agents, organic and inorganic compounds, metals, mineral deposits, and organisms like parasites, bacteria, and fungi. Water purification aims to remove as much foreign material from the water source as possible, making it suitable for human consumption or use.

    What is the best water purification system

    Commercial water purification also includes advanced purifying methods such as distillation and deionization. With the distillation process, the contaminated water is turned into vapor, then condensed back into liquid form as the contaminants fall out in the process. Deionization involves removing dissolved concentrations of salt and other material from the water source using specialized equipment.

    Commercial water purification

    The United States is known for its standard of living, due in part to the implementation of residential water purification standards that ensure clean drinking water. Numerous industries rely on commercial water purification, such as the medical sector, food and beverage production, pharmaceutical manufacturing, chemical engineering, and many more.

    Water Purification Treatment Steps

    water purification treatment steps

    Most commercial water purification processes follow a four-step method for purifying a water supply:

    1. Coagulation and flocculation
    2. Sedimentation
    3. Filtration
    4. Disinfection

    The first step involves isolating foreign matter in the water and making it more manageable. Dirt particulates pick up a negative charge as they move through the water. Adding a positively charged chemical agent to the water supply begins the purification process by neutralizing the dirt’s negative charge, causing it to coagulate into a larger mass known as “floc.”

    Unlike individual dirt particles, the resulting floc is much heavier, so clumped material drops out of the water and settles at the bottom. This step is called “sedimentation,” and it naturally follows flocculation.

    Coagulation and flocculation take care of most contaminants, but leftover particles or harmful bacteria such as E. Coli may survive the process. Additional filtration passes the water through a series of filters made out of sand, gravel, and charcoal to remove any remaining debris.

    coagulation and flocculation

    The final decontamination step will eradicate any remaining bacteria missed by the filters. Administering a safe ratio of chlorine will kill remaining organisms and prevent future bacteria growth. No matter how many filters the water passes through, decontamination remains essential because viruses, fungi, and bacteria are microscopic and may slip through.

    Deionizer Systems to Purify Water

    Deionization provides an extra layer of protection beyond the basic purification process. Through deionization, virtually all contaminants, including dissolved salts, are removed from the water. With many types of deionizing equipment and services on the market that offer a varying range of capabilities, the team at Reynolds Culligan often gets asked: What is the best water purification system for deionizing water?

    deionizer systems to purify water

    The answer to that question depends on the scale of the job at hand. Reynolds Culligan offers two different deionization solutions:

    • Culligan Premier Series Deionizer System. Our premier line of water purification systems can deliver ultra-purified water on an ongoing basis. Numerous industries contain applications that require “blank water.” Deionized blank water is 100% free from all contaminants. Our premier series offers full control over the deionizing process by allowing full resin tank customization. Users can create a combination of weak and strong base tanks suited to the specific application and choose between a manual and automatic regeneration process for additional control.
    • Culligan Portable Exchange Deionizer (PEDI) System. Our line of portable exchange deionizers offers an ideal solution for creating ultra-purified water from remote water sources. Our PEDI systems use a combination of activated carbon and high-quality ion exchange to give you access to clean, purified water in remote locations where mobility is required.

    Water Treatments With Reynolds Culligan

    Culligan® Premier Series Deionizer Systems

    Reynolds Culligan has a long history of excellence in commercial water treatment dating back to 1948. As the mid-Atlantic’s only single-source supplier of comprehensive water treatment technology, we work with virtually all industries to supply custom water purification platforms based on each company’s individual needs.

    Please contact us to set up your consultation for more information on our water treatment solutions.

  3. Deionized Water System vs Reverse Osmosis: Which is Best For Your Application?

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    There are many different filtration systems for water, two of the most common being reverse osmosis and deionization. While they are both effective in substantial ways, several misconceptions surround both of these processes. Here, the team at Reynolds Culligan clarifies how these systems work and answers frequently asked questions we receive about them to ensure you know which service is best for you.

    Deionization and reverse osmosis are both excellent at removing dangerous contaminants and minerals from water. Depending on the specifics of the system and the filtration stages involved, these systems can purify water by removing things like:

    • Salt
    • Sand and silt
    • Copper and iron
    • Arsenic
    • Magnesium and calcium

    Both are useful for cleaning because they don’t leave behind streaky mineral deposits. They also perform well in boilers and humidifiers, and they’re great in industrial application such as cosmetics, manufacturing, and aquariums.

    The biggest difference between the two is that reverse osmosis uses a semipermeable membrane to filter water, while deionization uses ion exchange resins to replace minerals and contaminants with hydrogen and hydroxyl ions.

    While both filtration systems offer approximately the same ability to remove contaminants from water, only reverse osmosis can remove protozoa, viruses and bacteria from the water. What deionization does have over reverse osmosis is that it can act as a water softener as well as a purifier.

    Reverse Osmosis

    Reverse osmosis systems use pressure to reverse the flow of water, so the water passes through a membrane and carbon filters to filter out chemicals, bacteria, and minerals. If you live or work in an area where heavy pesticides or herbicide use is an issue, reverse osmosis can remove these substances from your water.

    The U.S. military has used reverse osmosis to change salt water into fresh water for troops, and some countries use this technology during floods and relief efforts to help communities stricken by the disasters. The “pure water” created from the system also aids the environment by curbing the need for bottled water and the plastic waste left behind.

    There are some drawbacks to reverse osmosis systems. Some of the minerals stripped from the water, such as iron, calcium, manganese, and fluoride, are beneficial for humans and may lead to vitamin deficiencies in people with less well-rounded diets. A lack of fluoride in the water can also lead to a higher chance of cavities in children.

    Deionized Water

    Deionization is a water treatment process that targets mineral salt contaminants. The purification process removes cations, such as calcium, copper, iron, sodium ions, and anions such as bromide and chloride, out of the water. Deionization systems use tanks full of ion exchange resins to purify potentially contaminated water. The resins bind with any mineral salts in the liquid to separate them from water, so only clean water leaves the tank.

    Deionization tanks produce varying levels of purification depending on the resin and the exact type of deionization process, so it’s important to choose the appropriate solution for each particular case.

    The following applications require this process for purified water:

    Deionization can produce three grades of purified water: demineralized (deionized) water, high-purity water, and lab-grade and medical-grade water. Whereas car washes simply need water clean enough to not leave streaks on vehicles, pharmaceutical labs need water with every trace of mineral salts, contaminants, and organic material removed.

    Deionized water typically serves as a “perfect” cleaning solvent, an ultra-pure ingredient, and the foundation of a process water recovery/reuse strategy. It is used as an ingredient and a process element in food and beverage processing. As an ingredient, it offers stability, purity and sanitation. As a process element, it is used for effective sanitation.

    Deionized water is often mistaken as being the same as distilled water, but this is not the case. Both waters are healthy to drink, but deionized water is even purer. Distilled water conducts electricity whereas deionized water does not.

    Contact Reynolds Culligan for More Information

    Both deionization and reverse osmosis can greatly help filter out the impurities in water, but each system has its own features and drawbacks. The team at Reynolds Culligan is happy to help you make the best choice. Typically, one can cut operating expenses by using reverse osmosis before a deionized water system. This is called a mixed-bed deionizer. For the purest application, you would use deionized water.

    We are capable of delivering both deionization systems and reverse osmosis systems of the highest quality and output. Each system is personalized to the demands of our customers and the water in their location. We work with a tradition and knowledge built up over 70 years of innovation and service.

    You can contact us or request a quote today to get a free estimate and free water analysis.

  4. Reverse Osmosis Water Removes Many Common Contaminants

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    And a Culligan Reverse Osmosis Drinking Water System provides you and your family bottled-quality water right at your kitchen sink.

    You’ll use this water for so much more than just drinking!

    Boy Drinking WaterReverse Osmosis Water is Great to Use For:

    • Crystal-Clear Ice Cubes
    • Boiling Water for Cooking
    • Rinsing Fruits and Vegetables
    • Watering Plants
    • For Your Dogs, Cats, and all Your Pets

    Culligan Water Makes Almost Everything Taste Better

    • Teas
    • Coffees
    • Mixed Drinks (you’ll be amazed at the taste of your scotch and water with Culligan water)
    • Soups
    • Homemade Sauces (cooks love cooking with Culligan)

    AC30undersink_hi-resOur limited lifetime warrantied systems have the following state-of-the-art features:

    • Carbon Pre-Filter to Remove Chlorine and Bad Tastes & Odors
    • Sediment Pre-Filter
    • 30 Gallons/Day Reverse Osmosis Membrane
    • Carbon Polishing Filter
    • Limited Lifetime Warranty