Enhancement of multi-media filter performance using talc as a new filter aid material: Mechanistic study

• The filter outlet turbidity was decreased by increasing the talc dosage from 0 to 67.5 mg/l.
• When 67.5 mg/l of talc concentration was added to the suspension both running limits (turbidity and head loss) were not exceeded within the first 300 min of the filter run.
• Hydrophobic interaction was the key coagulation mechanism for talc.
• For talc to be used as a filter aid, it has to be applied to the suspension as an admix prior to the filtration process rather than a filter precoat.

The potential of using a new filter aid, namely, talc to enhance the removal of particles in a multi-media filter was investigated. In the case of the nano-scale particles the running time was enhanced by 300 min at a talc concentration of 67.5 mg/l. In the case of the micro-scale particles the running time was enhanced from 20 min to 40, 100, and 300 min at a talc concentration of 22.5 mg/l, 45 mg/l, and 67.5 mg/l, respectively. Coagulation was due to hydrophobic and chemical interactions between talc and the different suspensions.

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