Question

CLAY PARTICLES DO NOT SETTLE DOWN EASILY DURING THE PROCESS OF SEDIMENTATION. CAN YOU SUGGEST ONE METHOD TO MAKE THEM HEAVIER AND THUS HELP IN SEDIMENTATION? Name the method and the chemical

Answer 1

Answer:

Coagulation by additionmof chemicals such as aluminium sulfate also known as alum will help in sedimentation of clay particles.

Explanation:

Clay particles are very small particles found suspended water obtained from streams and rivers for township supply. They have weak electrical negative charges on their surfaces which when they approach one another, they repel each other thus making it almost impossible for clay particles to settle out of suspension.

Because of this, prior to the sedimentation step, a chemical process known as coagulation is required. In this process, certain chemicals called coagulants, are added to the water to bring the difficult-to-settle suspended particles such as clay particles together into larger, heavier masses of solids called flocs. They do these by interfering with the repulsive forces between the particles, thus allowing them to clump together into flocs. The most commonly used coagulant used for water purification is aluminium sulfate or alum. Other chemicals that are also employed in coagulation include ferric sulfate and sodium aluminate.