Climatic conditions and eutrophication of many aquatic ecosystem aid its development.
Due to the existence of the symbiosis, Azolla can grow in aquatic environments devoid of combined nitrogen, if there is enough phosphorus.
Infact, phosphorus is for Azolla, as for many other photoautrotrophic
aquatic organisms, the limiting nutrient
for growth. On the other hand, many eutrophication
problems in our country are due to the discharge of
domestic or industrial wastewaters only submitted to
secondary biological treatment. These effluents contains
high levels of nutrients and tertiary chemical
treatments for nutrient removal are very expensive