What action should be taken if filtration rates on a dual media filter exceed 5 GPM/sq ft and turbidity increases?

In the scenario where filtration rates on a dual media filter exceed 5 gallons per minute per square foot and turbidity increases, the most effective action is to add a polymer coagulant aid. When the filtration rate exceeds the recommended threshold, it indicates that the filter may not be able to effectively capture particulates, leading to increased turbidity in the filtered water.

Adding a polymer coagulant helps bind and agglomerate smaller particles, making them larger and more easily captured by the filter media. This process improves the overall efficiency of the filtration system and helps lower turbidity levels. Polymers can enhance the clarity of water by facilitating the removal of fine particles which would otherwise pass through the filter, particularly in conditions where the filter is nearing its operational limits.

Controlling turbidity through the introduction of coagulants is a common practice in water treatment, particularly when faced with increased particulate loading. This helps to ensure that the quality of the treated water meets safety and aesthetic standards.