Effective methods include:

Vacuum Dehydration and Degassing: Removes moisture and gases efficiently.
Filtration Systems: Multi-stage filtration to eliminate particulates.
Adsorption Techniques: Using materials like activated alumina or Fuller’s earth to remove acids and polar compounds.
Centrifugation: Separates contaminants based on density differences.
Electrostatic Precipitation: Removes fine particles using electric fields.
Combining these methods often yields the best results, ensuring comprehensive purification of cable oil.