In wastewater treatment, pneumatic diaphragm pump is mainly used to transfer and feed thickened sludge to hydraulic chamber filter press and plate-and-frame filter press for sludge dewatering. Also it can be used to transfer fluid from the most sludgy home heating oil, hydraulic fluid, motor oil, and even water.

Two working chambers are symmetrically located at the two sides of a pneumatic diaphragm pump, each working chamber is equipped with one elastic diaphragm, connected through a connection rod.

Compressed air access into valve chest and push the diaphragm of one working chamber, because of the connection of the connection rod, another diaphragm will move too at the same time. When the volume of a chamber is increased, the pressure decreases, and fluid is drawn into the chamber. When the chamber pressure later increases from decreased volume, the fluid previously drawn in is forced out. Finally, the diaphragm moving back once again draws fluid into the chamber, completing the cycle.