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Inorganic coagulants

The role of coagulation in water treatment is important: it is the process of reducing the electric repulsion between particles by the addition of iron or aluminum salts (inorganic coagulants) to the water. The positive charge of the inorganic coagulant neutralizes the negative charge of the particles in the water, causing the particles to aggregate. During the coagulation process, flocs grow to a limited size, depending on pH, temperature, dose, shear rates, and the type of coagulant used. Coagulation can successfully remove a large amount of particles (including most of the microplastics) and dissolved matter from water. In many applications, such as phosphorus removal from wastewater, chemical treatment using an inorganic coagulant has been shown to deliver better results than any other method.

In wastewater treatment, choosing the right coagulant and dosage is very important. The pH of the wastewater is also very significant – the optimum pH range for precipitation with aluminum salts is between 5-7, while iron salts can be used in the range 5-11.

Kemira’s range of inorganic coagulants used in water treatment is the most comprehensive in the industry and includes a variety of aluminum based coagulants, iron sulphate based coagulants and iron chloride based coagulants. We manufacture the inorganic coagulants at multiple locations around the world, which ensures fast delivery and high security of supply.

From a sustainability point of view, most of the raw materials used in coagulants originate from industrial by-products; these are known as Alternative Raw Materials (ARMs) and they result in a lower carbon footprint for both iron and aluminum coagulants. We supply sustainable water treatment chemistries to various water-intensive industries and municipal wastewater treatment.

Applications for inorganic coagulants include e.g. the following:

  • Municipal and industrial wastewater treatment
  • Potable water treatment / drinking water production / raw and surface water treatment
  • Specific industrial applications where inorganic coagulants are used as raw materials

Aluminum and iron based coagulants are used in a variety of water treatment applications, such as particle removal (including microplastics), TOC removal, phosphorus removal (chemical precipitation), BOD and COD removal (removal of oxygen consuming organic substances), color removal, metals removal, hydrogen sulfide removal, sludge conditioning, sludge dewatering, bulking sludge or lake restoration.

Aluminum based coagulants can vary to a great extent in terms of product properties. It is therefore possible to find a suitable aluminum coagulant for basically any purpose.

The advantages include:

  • High purity and low iron content.
  • Quick floc formation and settling, higher processing capacity
  • Strong adaptability to changes in turbidity, alkalinity, and organic matter content.
  • Good flocculation effect can be maintained for low temperature, low turbidity water quality.
  • The amount of residual free aluminum is low, and the water quality after purification meets the requirements of national standards.
  • Corrosion is minor, the powder is easy to dissolve, better than other similar products.

Main product categories of aluminum-based coagulants:

  • Aluminum sulfate
  • Polyaluminum sulfate
  • Aluminum chloride
  • Polyaluminum chloride
  • Aluminum chlorohydrate
  • Sodium aluminate
Trade name Chemistry Form
Kemira ALS Aluminum sulfate Liquid
Kemira ALG, ALK, AVR Aluminum sulfate Dry
Kemira PAS Polyaluminum sulfate Liquid
Kemira ACL Aluminum chloride Liquid
Kemira PAX Polyaluminum chloride Dry & liquid
Kemira PAX, ACH Aluminum chlorohydrate Liquid
Kemira SAX Sodium aluminate Liquid

Iron based coagulants, or ferric salts, are soluble over a very broad pH range making them very useful for many water treatment applications, both municipal and industrial.

The advantages include:

  • High purity and low heavy metals content
  • Quick floc formation and settling, higher processing capacity
  • Ideal for removing common metals such as Cu, Ni, Zn etc.
  • Used for hexavalent chrome reduction, and as an aid to flocculation.
  • Treating oily water, removing turbidity
  • Wide range of pH values are used, ranging from 5.0 to even up to 11.
  • Improving sludge dewaterability
  • Highly effective in hydrogen sulfide removal in biogas applications
  • Coagulation works well in low temperatures

Main product categories of iron-based coagulants:

  • Ferric chloride
  • Ferrous chloride
  • Ferric sulfate
  • Ferrous sulfate
  • Ferric chloro sulfate
Trade name Chemistry Form
Kemira PIX Ferric chloride Liquid
Ferrous chloride
Ferric sulfate
Ferrous sulfate
Ferric chloro sulfate
Kemira Ferix Ferric sulfate Dry
Kemira COP Ferrous sulfate Dry
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