how many water treatment plants use anion exchange resin

How much water can an anion exchange device remove?

The amount of water an anion exchange device can treat depends on the contaminant being removed. If removing nitrate, the removal capacity will depend on both the nitrate and the sulfate concentration in the water, as anion exchange resins preferentially adsorb sulfate.

How do IX resins work in industrial water treatment?

Ion exchange systems facilitate reversible chemical reactions in which the ions targeted for removal are captured electrostatically and replaced by other ions of similar charge. Key components of IX systems are ion exchange resins. This one-page reference provides an overview of how IX resins work in industrial water treatment.

How widely used are ion exchange resins in the US?

Gel resins are the most broadly used resins in the United States. In an analysis of ion exchange resin samples sent in for analysis to a major laboratory1, only approximately 2 percent were samples of macroporous resins.

How do you make anion exchange resins?

The preparation of anion-exchange resins is more complicated. At first chloromethyl groups need to be introduced, the reactive chlorine atoms, of which are then substituted by any appropriate amino group in the second reaction step; the so-called amination process.

Which water treatment process uses ion exchange?

water softeningA typical example of ion exchange is a process called “water softening” aiming to reduce calcium and magnesium content. Nevertheless, ion exchange is also efficient in removing toxic metals from water....Executive Summary.InOutFreshwater, Treated WaterTreated WaterMay 24, 2019

Where are ion-exchange resins used?

Ion exchange resins are used to soften water by replacing the cations with sodium ions (and possibly the anions with chloride ions) of sodium chloride. They may also be used to demineralize water where the cations are replaced by H+ ions and the anions are replaced by OH− ions.

How many types of ion exchange resin are there?

twoThere are two general types of ion exchange resins: those that exchange positive ions, called cation exchange resins, and those that exchange negative ions, called anion exchange resins. A cation is an ion with a positive charge.

What is anion exchange water treatment?

Water softeners remove cations (positively charged ions such as calcium and magnesium) and replace them with sodium. Anion exchange devices remove anions (negatively charged ions such as arsenic and nitrate) and replace them with chloride.

What are the 4 types of ion exchangers?

Ion exchangers can be ion exchange resins (functionalized porous or gel polymer), zeolites, montmorillonite, clay, or even soil humus.

Which resin is used for water softening?

SAC resin is effective for water softening, which removes hardness ions. It has been used in residential, commercial and industrial applications for more than 100 years. Like tiny magnets, SAC resin beads remove scale-forming calcium (Ca2+) and magnesium (Mg2+) ions by exchanging them for sodium ions.

What are the two types of resin?

The types of resin which we will be discussing are as follows, Epoxy Resin, Uv Resin, Polyester Resin and Polyurethane Resin. The majority of resins are made up of two elements, namely the base resin and a catalyst (which is a hardener).

How many main classes of ion exchangers exist?

The four subdivisions are: Strong acidic cation exchange resins. Weak acidic cation exchange resins. Strong basic anion exchange resins.

What are the types of ion exchange materials?

Ion Exchange MaterialIon Exchange.Zeolite.Adsorption.Resin.Exchange Membrane.Functional Group.Ion Exchanger.Exchanger.

How does anion exchange resin work?

Put simply, ion exchange is a reversible interchange of charged particles—or ions—with those of like charge. This occurs when ions present on an insoluble IX resin matrix effectively swap places with ions of a similar charge that are present in a surrounding solution.

How much ion exchange resin do I need?

Ion exchange resins have a capacity of approximately 1 equivalent per liter of resin. Your requirement is small, you may want to consider a cartridge type system. If you do a regular column, you can buy in the market a 6" X 48" column. Fill it to about 30" height.

What is exchange capacity of resin?

Definitions. In general terms, the capacity of an ion exchange resin can be expressed as the quantity of ions that can be taken up by a specific volume of the resin.

What are the different types of resins used in water treatment?

There are four major classes of resins used in industrial water treatment: strong acid cation, weak acid cation, strong base anion and weak base anion. Each of these major resin classes has several physical or chemical variations within the class. The variations impart different operating properties to the resin. A good ion exchange system designer not only will design the system to meet all design specifications but also will utilize resins that will allow the system to operate at peak efficiency and maximum cost effectiveness.

What is a weak acid cation resin?

Weak acid cation (WAC) resins can be used in demineralization and dealkalization systems. They are very efficient when matched up with the proper influent water chemistry. In the study referenced previously, only 2.6 percent of the samples submitted for analysis were WAC resins and of these, 63 percent of them came from locations outside of the United States. With many water supplies in the United States being high in hardness and alkalinity, these figures may indicate that system designers in the United States largely ignore the use of WAC resins. Designers of industrial water treatment systems may want to look at WAC resins more often in an effort to improve system performance and decrease operating costs.

What is SAC resin?

Strong acid cation (SAC) resins probably are the most common resins in use today. They are used in softening and demineralization applications. In softening applications, the resin is used in the sodium form (regenerated with salt) and in demineralization applications the resin is used in the hydrogen form (regenerated with acid). SAC resins also can be used in a split-stream dealkalization process. SAC resins can be purchased with different percentages of crosslinkage. The common SAC resin is 8 percent crosslinked. However, SAC resins are available in both higher and lower levels of crosslinkage. Often a 10 percent crosslinked resin will be used in applications where the influent water has a higher level of chlorine or an elevated water temperature. Chlorine as well as oxygen at elevated temperatures will attack a resin's crosslinkage. Having the higher initial level of crosslinkage often will provide for a longer useful resin life. SAC resins with less than 8 percent crosslinkage may be used in electric utility condensate polishing applications where they are reported to do an excellent job of removing corrosion products (crud) from the utility's condensate.

What is a weak base anion?

Weak base anion (WBA) resins actually are acid absorbers as much as they are ion exchange resins. They remove only the anions of the strong mineral acids (sulfate, chloride and nitrate). They allow the carbonate/bicarbonate and silica ions to pass through. Therefore, they cannot be used to make demineralized water without a SBA resin bed following in the train to remove the carbonate/bicarbonate and silica. The advantage of using the WBA resin is its efficiency. It is fully regenerated using only about 120 percent of stoichiometry. Like their WAC counterparts, WBA resins can be regenerated using the spent caustic from the SBA resin bed making their use very efficient especially when used on water having a high percentage of anion loading from sulfate, chloride or nitrate.

Why are nanoparticles used in water?

Nanoparticles are particularly preferred because of their higher surface area , hence more adsorption. Some instances are mentioned in the following:

Why is zirconium oxide good for water?

Zirconium oxide nanoparticles are favorable for removal of arsenic from water, because of their stability and nonreactivity. Unlike ceria nanoparticles which are pH dependent, zirconium oxide nanoparticles operate irrespective of the prevailing pH conditions ( Cui et al., 2012 ).

Why are hydroxyl ions important?

This is important for the conversion of these resins to the hydroxyl (or free base) form in the regeneration step , in which only slightly more than the stoichiometric amount of OH– bearing solutions is required.

What are the two main categories of IX resins?

IX resins’ two main categories are cation and anion. Cation IX resins include strong/weak cation, (H+ and Na+). Anion IX resins include a strong/weak anion, such as OH- and Cl-. Acting together or alone, these types remove many ionic contaminants from water. Neither type removes non-ionic contaminants such as benzene.

What is IX resin?

Ion exchange (IX) resin technology has been used extensively as a practical and effective form of water treatment for many years. IX is often used with water softening, which is its most common application. However, IX resins have many other applications.

What is a negatively charged anion resin?

Negatively charged anion resins remove negatively charged ionic contaminants in water. Included in this category of resins are strong base/strong anion (SBA) and weak base/weak anion (WBA) resins. These anion resins can be used to remove the contaminants described in this section.

What is the IX process?

Specialized IX resins address these challenges. The IX process removes soluble ionized contaminants such as hardness ...

What is SAC resin used for?

SAC and SBA resins employed in combination either individually or mixed together can be used to reduce minerals and TDS in water. Minerals in the water are exchanged with hydrogen cations (H +) and hydroxide anions (OH –) from the resin beads to form highly purified water (H 2 O).

How much hardness is removed by WAC resin?

Generally, WAC resin removes about 80 percent of the temporary hardness (hardness associated with dissolved bicarbonate minerals). TDS are reduced by about 17.1 parts per million (ppm) for each grain of hardness removed.

What is TOC in water?

TOC. Total organic carbon (TOC) or naturally occurring organic matter can be oxidized by secondary chlorine disinfection and create DBPs, such as THMs and HAAs. These DBPs are suspect carcinogens and regulated by the EPA in drinking water. Municipal treatment plants sometimes remove TOC to limit the formation of DBPs.

How does biological treatment reduce contaminant in water?

As contaminated water flows through the bed, the bacteria, in combination with an electron donor and nutrients, react with contaminants to produce biomass and other non-toxic by-products. In this way, the biological treatment chemically “reduces” the contaminant in the water.

What is the process of cation exchange?

In a cation exchange treatment process, water passes through a bed of synthetic resin. Positively charged contaminants in the water are exchanged with more innocuous positively charged ions, typically sodium, on the resin’s surface.

What is PTA in water?

Packed tower aeration (PTA) uses towers filled with a packing media designed to mechanically increase the area of water exposed to non-contaminated air. Water falls from the top of the tower through the packing media while a blower forces air upwards through the tower.

What are some examples of nontreatment options?

Examples include interconnection with another system and drilling a new well to replace a contaminated one.

What is granular activated carbon?

Granular activated carbon (GAC) is a porous adsorption media with extremely high internal surface area. GACs are manufactured from a variety of raw materials with porous structures including: Physical and/or chemical manufacturing processes are applied to these raw materials to create and/or enlarge pores.

What is the process of water passing through a semi-permeable membrane?

These processes force water at high pressure through semi-permeable membranes that prevent the passage of various substances depending on their molecular weight. Treated water, also known as permeate or product water, is the portion of flow that passes through the membrane along with lower molecular weight substances.

What is an active bioreactor?

An active bioreactor will have a continuous growth of biomass that needs to be periodically removed. Although the excess biomass will not be contaminant-laden, it still requires disposal. Also, biological treatment adds soluble microbial organic products and can deplete the oxygen in treated water.

Use of Resin for Water Treatment

While many of us have heard of ion exchange (IX) resins, few of us have a grasp on how the technology actually works. Whether you’re weighing potential treatment strategies,looking for ways to get the most out of your existing IX resins or simply curious about IX chemistry, you may be asking “What is ion exchange resin and how does it work?”

What are ion exchange resins?

Ion exchange is a reversible chemical reaction where dissolved ions are removed from solution and replaced with other ions of the same or similar electrical charge. Not a chemical reactant in and of itself, IX resin is instead a physical medium that facilitates ion exchange reactions.

How to use resin for water treatment

This attraction is used to remove dissolved ionic contaminants from water. The exchange process occurs between a solid (resin or a zeolite) and a liquid (water). In the process, the less desired compounds are swapped for those that are considered more desirable. These desirable ions are loaded onto the resin material.

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What is an IX resin?

IX resins are generally composed of crosslinked organic polymers shape d into small beads usually measuring between 0.25 and 1.25 mm in diameter. The most common IX resin material is polystyrene with divinylbenzene crosslinks. This type of resin is used in the majority of IX applications.

What happens when water flows through resin beads?

In general, water containing undesirable ions flows through a bed of resin beads and the problematic ions are exchanged for ions of similar charge that were first applied to the resin. The functional groups and initial counterions are designed such that the ions in the treated water will have a greater affinity for the charged functional groups and will dislodge the existing ions and take their place, bonding with the functional groups through shared electrostatic attraction [ 2 ].

What is an ion exchange system?

Ion exchange systems facilitate reversible chemical reactions in which the ions targeted for removal are captured electrostatically and replaced by other ions of similar charge. Key components of IX systems are ion exchange resins. This one-page reference provides an overview of how IX resins work in industrial water treatment.

What is resin flushing?

By flushing the resin, the contaminant ions are released into a waste stream, and the cations and anions in the resin are restored for another cycle. Resins are designed to resist thermal degradation and oxidizing agents, as well as organic fouling.

What is the use of a weak acid cation exchange resin?

Weak acid cation exchange resins derive their exchange activity from a carboxylic group (-COOH).

Why should a regenerant distributor be secured to the tank structure?

The regenerant distributor should be secured to the tank structure to prevent breakage and subsequent channeling of the regenerant. Water is softened by the bed of strong acid cation exchange resin in the sodium form.

What is the difference between cation anion demineralization and zeolite softening?

The primary difference is that the vessels, valves, and piping must be made of (or lined with) corrosion-resistant materials. Rubber and polyvinyl chloride (PVC) are commonly used for ion exchange vessel linings. The controls and regenerant systems for demineralizers are more complex, to allow for such enhancements as stepwise acid and warm caustic regenerations.

How does a demineralizer work?

In a conventional demineralizer system, regenerant flow is in the same direction as the service flow, down through the resin bed. This scheme is known as co-current operation and is the basis for most ion exchange system designs. During the regeneration of a co-current unit, the contaminants are displaced through the resin bed during the regeneration. At the end of the regeneration, some ions, predominately sodium ions, remain in the bottom of the resin bed. Because the upper portion of the bed has been exposed to fresh regenerant, it is highly regenerated. As the water flows through the resin during service, cations are exchanged in the upper portion of the bed first, and then move down through the resin as the bed becomes exhausted. Sodium ions that remained in the bed during regeneration diffuse into the decationized water before it leaves the vessel. This sodium leakage enters the anion unit where anion exchange produces caustic, raising the pH and conductivity of the demineralized water.

What is the process of demineralization of water?

Demineralization of water is the removal of essentially all inorganic salts by ion exchange.

What is the purpose of ion exchange systems?

Ion exchange systems are used for efficient removal of dissolved ions from water.

Is ion exchange resin ionizable?

In addition to a plastic matrix, ion exchange resin contains ionizable functional groups. These functional groups consist of both positively charged cation elements and negatively charged anion elements. However, only one of the ionic species is mobile. The other ionic group is attached to the bead structure.

Ion Exchange Resins

• There are four major classes of resins used in industrial water treatment: strong acid cation, weak acid cation, strong base anion and weak base anion. Each of these major resin classes has several physical or chemical variations within the class. The variations impart different operating properties to the resin. A good ion exchange system designer...

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Resin Structure

Strong Acid Cation Resins

Weak Acid Cation Resins

Strong Base Anion Resins

Weak Base Anion Resins