Bio-odor removal boxes utilize a large surface area of bio-fill material where microorganisms attach and grow. In a suitable environment, these microorganisms form a biofilm on the bio-fill surface. The microorganisms within the biofilm use inorganic and organic substances from the waste gas as carbon and energy sources. They maintain their life activities by degrading malodorous substances and convert them into odorless substances such as water, carbon dioxide, minerals, etc., achieving the goal of VOCs purification treatment.