Understanding Corrosion in Water Pipelines: A Guide for Pipeline Designers



Last updated: August 14, 2018

What Does Coagulant Mean?

This is an inorganic or organic substance that initiates or aids a congealing process during water treatment. A coagulant, together with other chemicals, are added in water to aggregate dissolved contaminants and tiny particles into larger particles so that filtration, clarification, or any other solid removal process may be used to remove them. Inorganic coagulants, except the sodium aluminate (which is basic), decrease alkalinity levels in water. This helps to reduce risks of corrosion attack in pipes transporting wastewater.


Corrosionpedia Explains Coagulant

A coagulant is used in colored, low pH or alkaline and low turbidity water. The optimum pH it generates helps in water purification. The coagulate dose used in purification produces a hydrolysis process that generates a pH suitable for coagulation. The metal hydroxide formed is what adsorbs the impurities (humus) to form compounds that become flocs. These flocs can later be filtered out since they are suspended solid bodies and when heavy they settle at the base.

The importance of a coagulant is:

  • To destabilize the acidity of the fluid and cause flocs formation.
  • Purify the fluid by removing unwanted active metallic or non-metallic elements

An inappropriate coagulant dose might lead to corrosion due to acidity, hence one must follow guidelines by the governing authority. To improve on filtration, certain guidelines are placed to govern the change of coagulant in any filtration process. The use of coagulant aid improves on the performance of the coagulant used.


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