Aeration is a key biological method in the secondary stage of wastewater treatment, used in the activated sludge process by municipal facilities globally. Market growth is led by the need for refurbishment of old infrastructure, demand for new constructions and increased wastewater treatment services. The most growth is expected from the diffused aeration technology segment. Regional variations exist due to the historical focus and expenditure on infrastructure development in individual countries. The increased significance of aeration's energy intensity promotes innovation.