How to Use Aluminum Sulfate As a Floculant

Written by william rockwell
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Flocculation is the process in which tiny solid particles that are suspended in water with a high negative electric charge. This process involves mixing a highly ionised substance into the water to neutralise the charge to allow the small particles to produce a precipitant that is large enough to be filtered by standard media filters. Aluminium sulphate is one of the most common neutralisers used in water treatment plants and purification stations.

Skill level:

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Things you need

  • Aluminium sulphate
  • Water treatment tank
  • Filtration media
  • Water pump
  • Mixing paddle
  • Empty 1-gallon jug
  • Clean measuring cup
  • Marker

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  1. 1

    Obtain aluminium sulphate flocculant material from a chemical supply store.

  2. 2

    Pour 473ml. of water into the empty gallon container. Mark this spot with a felt tip marker. Label it 473ml. Put another 473ml. of water in the container and mark it again, this time labelling it 907gr. Continue this process until the container is full.

  3. 3

    Drain off some of the water so that the remaining water is approximately 3,548ml. The solution only needs to be made in approximation so precision isn't required.

  4. 4

    Measure out 113gr. of aluminium sulphate powder and pour it into the container.

  5. 5

    Cap the container and shake it for 30 seconds to create a homogeneous mixture.

  6. 6

    Add 454gr. of this mix to the treatment tank for every 240 gallons of water to be precipitated.

  7. 7

    Stir the water in the treatment tank with a large paddle to create turbulence and allow the electrochemical balance of the treatment tank to neutralise.

  8. 8

    Turn on the filtration system. As the flocculant begins the precipitation process, large chains of particles will begin to form flocs. These flocs will fall out of suspension toward the bottom of the tank. Here the filtration media will catch them and clear the water.

Tips and warnings

  • The aluminium sulphate flocculant will come in a tablet or powder form that can be dropped directly into the water tank as well. Tablets come prepacked to treat one ton (240 gallons) of water. For smaller applications a powder is suggested.

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