In order to respond effectively to the problems that arise - for example - in cities due to smell nuisance from public sewage networks, the company Biothys™ has developed the patented technology Gelactiv SHK or NHK, which allows both a targeted local and global treatment to eliminate malodorous gaseous emissions in the urban sewage system. Gelactiv SHK technology can treat the airflow directly in the ducts, regardless of their length or configuration, as well as the nature of the wastewater tanks.