How Coagulants Work In A Water Treatment System

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Both drinking water and wastewater treatment depend on flocculation and coagulation.

Every body of water has suspended matter. The physical forces (static electricity) acting on the tiniest particles (colloids), which all have a negative charge when suspended in water, resist one another and stabilize the colloids.

This article will go into greater detail on the usage of coagulants in water treatment systems.

What are coagulation and flocculation in water treatment?

They both offer a dependable method for addressing water turbidity, a crucial indicator of water quality. Turbidity is defined as the cloudiness or haziness of a fluid that is normally imperceptible to the naked eye.

To overcome the forces that keep the suspended particles stable, flocculation and coagulation are two distinct processes that are used in succession.

The particles' charges are neutralized by coagulation, but they can bind together and grow in size by flocculation, making it easier to remove them from the liquid.

The coagulation process in water treatment

This stops the tiny particles from repelling one another and encourages their aggregation into larger particles that can stick together. The easier it is to extract a particle from a liquid, the larger the particle.

Micro-flocs are these bigger 'clumps' of particles, which are sometimes invisible to the unaided eye. This will indicate that the charges on the freshly generated particles have been neutralized because the water surrounding them should be clean.

More coagulant may be required if it isn't. If there is too much coagulant present, the particles will return to repelling one another, primarily due to the reverse charge.

The coagulant is suitably distributed to encourage particle collisions thanks to rapid mixing. Because the most potent metal coagulant hydrolysis products are those that develop between 0.01 to 1.0 seconds, post-dosing with additional coagulant and adjusting pH is rarely effective after the initial injection of coagulant.

Back-mix reactors, a popular variety of quick mixers, typically have square tanks with vertical impellers. WCS designs in-line mixers with velocity gradient control to provide the ideal circumstances for quick mixing, mostly by the reverse charge, because they frequently produce subpar results.

water treatment system

Types of coagulants

In the treatment of both water and wastewater, there are two main categories of coagulants. Organic and inorganic

Inorganic coagulants

The removal of the majority of suspended particles has been demonstrated to be very successful using both aluminum and iron coagulants. They provide several benefits, including:

• Facilitate the creation of highly charged ions that have a high charge density to neutralize suspended particles, hydrate inorganic hydroxides, and generate short polymer chains that promote the formation of micro flocs and heavy flocs.

• Able to filter out some of the organic precursors that could interact with chlorine to create disinfection byproducts

• Affordable unit prices and extensive availability 

They have some disadvantages:

• They produce enormous amounts of metal-rich floc that must be disposed of in an environmentally responsible manner, which can significantly increase disposal costs.

• They have the potential to drastically change the water's pH, which calls for pH regulation because pH is necessary for proper coagulation. They also need feed and warehousing equipment that is corrosion-resistant.

• Ferrous sulfate, ferric sulfate, and aluminum sulfate are all extremely acidic substances that deplete alkalinity and lower pH. On the other side, sodium aluminate will increase pH and enhance alkalinity.

Organic coagulants

The removal of the majority of suspended particles has been demonstrated to be very successful using both polyamine and poly-DADMAC coagulants. Tannates work very well with fats and oils. They provide several benefits, including:

• Make it possible for relatively low charge densities to more efficiently neutralize lesser charged suspended particles. without using metals or hydroxides, create longer polymer chains that will improve micro flocs production.

• Able to filter out some of the organic precursors that could interact with chlorine to create disinfection byproducts

• Liquid forms, non-corrosive, and ready for immediate use.

• Do not affect and are rarely or hardly impacted by pH

They have some disadvantages:

• Increased unit price

• If charge demand is great, large dosages are required.

• Low-density floc: Doesn't always settle smoothly.

Contact us for your water treatment system

Finally, failure to uphold wastewater treatment's environmental requirements exposes companies to growing environmental scrutiny and serious reputational concerns.

Contact us for wastewater treatment systems before making a case for capital funding may not initially be economically feasible.


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