In several points of a treatment plant it is necessary to lift more or less considerable quantities of sewage. The Archimedean screw pumps (PVA) are generally used at the inlet or at the intermediate stages of the plant, for the lifting of the whole inflow and/or for the sludge recycle and transfer. They shall be preferred to the standard centrifugal pumps due to the very large flow clearance which makes the clogging impossible, the high hydraulic efficiency and the particular characteristic of flow self-adjustment according to the water level in the suction well. Moreover the lifting units often absorb most of the total energy required by the plant. It is therefore more and more necessary to maximize the relevant hydraulic efficiency.
PVA – Archimedean screw pump