Clarification is the main solids/liquid separation process in any modern drinking water plant. The clarification system improves the quality of the water by removing the particulate material that causes turbidity and discoloration.

Clarification occurs upstream of the filters. By removing as much solids as possible from the influent, it lowers the solids concentration, or load, on the granular filters. Effective clarification permits longer filter runs and helps to reduce filter problems such as mudball formations. Effective clarification makes your filters work better.

In addition to the preparation of raw water for filtration, clarification is used in backwash water recovery.

The ideal clarifier will maximize the quality of the water product from the process while minimizing the amount of sludge produced, reducing the need for expensive residuals handling facilities.

The practice of clarification is ancient. It began when people realized that water quality could be improved by storing it undisturbed and then pouring or ladling it with little agitation. The first "municipal" applications of clarification were evident hundreds of years before the Christian era when reservoirs or storage tanks were constructed. Although they were constructed for strategic purposes, these reservoirs and storage tanks did improve water quality.

There are principally two methods of clarification: sedimentation and flotation. Which method is most appropriate for a particular application depends on the water to be treated as well as the circumstances and requirements of the water treatment plant.

See also:

• Methods of Clarification
• Clarification Process Selection
• Backwash Water Recovery

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