Sterilization of liquid paraffin is done by:
Key Points 
Hot air oven is used in laboratories and clinics for heat-resistant items that are not sterilized well by moist heat. They are used for sterilization of: 

Glasswares (syringes, Petri dishes, flasks, pipettes, test tubes, etc.)
Surgical instruments (scalpels, scissors, forceps, etc.)
Chemicals (liquid paraffin, sulfonamide powders, etc.)
Oils that are not penetrated well by steam used in moist heat sterilization. 

Parija SC. Textbook of Microbiology & Immunology. Elsevier Health Sciences; 2014. Page:27
Autoclaving
Hot air oven
UV radiation
Inspissation