What is antiscalant

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Antiscalant
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Antiscalant

• Antiscalant is a pretreatment water additive
  for Reverse Osmosis(RO) System that is very
  effective for preventing the membrane from
  scaling.
• It is injected into the water before feed
  water enters the reverse osmosis membrane. This
  chemical creates a time delay between bicarbonate
  and calcium, magnesium. This delay allow the
  water to pass through membrane before any
  chemical reaction occurs that can cause scale
  formation. This results to not forming scale on
  membrane and purify water easily.

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Need of Antiscalant

• Antiscalant chemical is used to prevent the
  scaling and fouling of Ro membrane. Scale may
  consist of minerals such as calcuim sulphate,
  calcuim carbonate, silica and calcuim fluride.
• To avoid this scaling, proper dosing of
  antiscalant should be done.
• Antiscalant chemical is used to process feed
  water at very high rate of recovery. When use
  properly, antiscalant extends the time of
  membrane cleaning from some months to almost an
  year. Without antiscalant, ro membrane system
  would not be as successful serving the water
  treatment industry.

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How Antiscalant Works

• There are basically three mechanism of
  action-
• Antiscalant avoid cation and anion of a
  scaling salt to react and form a precipitate.
• If they react and precipitate, the chemical
  avoid it to develop and become larger.
• And finally, even if precipitates are
  formed, the antiscalant promote a distortion in
  the crystalline structure of percipitate, making
  it more round and incapable of attaching to the
  ro membrane.

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Benefits of Antiscalant

• Antiscalant controls scales including silica,
  calcuim carbonate, calcuim sulfate and barium
  sulfate.
• Maintain cleaner membrane surfaces by dispersing
  foulants.
• Ro system can be run with high recovery rate for
  long time.
• Effective over a wide PH range.
• It increase the service life of membrane as well
  as ro system.

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How to select appropriate antiscalant for you?

• To determine the correct antiscalant and
  dosage, the ion species in water must be identify
  and their concentration have to be calculated.
• Then we can calculate the potential of ions in
  the water to form a scale, and the antiscalent
  will be selected based on the type of scale most
  likely to be formed.
• For example, if the water have potential to
  form both calcuim carbonate as well as calcuim
  sulfate.
• Antiscalant that can control both of these
  scales would be selected.

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Dosage

• Dosage is calculated based on the driving
  force for scale formation, which depends on the
  concentration of ionic species, temperature, PH
  and ionic strength.
• There are also other parameters that have to
  be taken to calculate dosage.
• For example, antiscalant have a high affinity
  for certain surfaces, like ferric hydroxide
  salts.
• So when iron is present in ferric state,
  higher dosage is required.
• 2 mg/l to 10 mg/l dosing of antiscalant is
  often required.

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Uses of Antiscalant

• Antiscalant can be used alone, but are
  usually used with acid feeds. It is most widely
  used because it offers good inhibition of calcuim
  carbonate and metallic sulfate scale.
• It is Widely used in the operation of Ro
  Plant and Nanofiltration(NF) systems.

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Thank You