Polymer impact on filter blinding during alum sludge filtration

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Filtration Science

Background:

• Alum sludge filtration is crucial for water treatment.
• Excess polymer dosing can lead to filter medium clogging.
• Understanding clogging factors is essential for optimizing filtration efficiency.

Purpose of the Study:

• To investigate factors controlling filter medium clogging during alum sludge filtration with excess polymer.
• To determine the relationship between polymer dose, particle size, and filter hydraulic resistance.
• To elucidate the role of polymer-colloidal interactions in filter blinding.

Main Methods:

• Experimental investigation of filter medium clogging.
• Analysis of hydraulic resistance in relation to trapped polymer and colloidal fractions.
• Evaluation of particle size and aggregate formation influenced by polymer dose.
• Assessment of polymer/colloidal solids ratio impact on filter resistance.

Main Results:

• Filter clogging is driven by the interaction of residual polymer and colloidal fractions.
• Low trapping efficiency occurs when either polymer or colloidal fraction is absent.
• Polymer coatings on the filter do not significantly impact hydraulic resistance.
• Clogging and polymer trapping are particle size-driven, with aggregate size dependent on polymer dose.
• Filter resistance trends are influenced by the polymer/colloidal solids ratio affecting particle size.

Conclusions:

• Filter clogging in alum sludge filtration under excess polymer is a complex phenomenon.
• The interplay between polymer and colloidal particles, mediated by particle size, is the primary cause of clogging.
• Optimizing the polymer/colloidal solids ratio is key to mitigating filter blinding and improving filtration performance.