Our range of PermaBio units are designed to provide high efficiency in removal of odour. The units operate counter current. With competing shell systems the shell media is active in the scrubbing process and breakdown which dramatically reduces the removal efficiency of the biofilter. With the Silotank PermaBio range the media is inactive and does not breakdown with the result that removal efficiency is guaranteed 100% of operational time. Under IPPC you must prove that the biofilter will provide the same removal efficiecy consistently. This cannot be guaranteed with traditional shell systems.