- Air blowers used in effluent treatment plant supplies the desired quantity of oxygen to the live organisms. Air blower is a rotary, positive displacement type of machine used to move air and is used in biological system of effluent treatment plant. Rotary blowers and positive displacement blowers are just two of several types that are available. WTT offers a wide range of blowers such as regenerative, reciprocating, rotary lobe and centrifugal blowers. They are available in single or multistage versions. All WTT blowers, as different in size, performance or technology as they might be, offer reliable service for our customers' applications. The blower which is supplying air to the disc diffuser system is been operated automatically, based on the online DO meter.