Parshall Flumes at Wastewater Treatment Plants

Over the years, Parshall Flumes have become common sights at wastewater treatment plants (WWTPs) across the US.  The flumes can be found at a number of points throughout the plant.   

Headworks

Many plants rely on Parshall Flumes to measure headworks flows.  Depending upon the plant size, the flumes may be cast in concrete channels or simply in-line with the feed line (smaller flows / package plants).

Effluent Flows

Parshall Flumes are also used to measure treated effluent as it exits the chlorine contact chamber or UV system – although in some UV applications the low head loss of a Parshall Flume is not desirable (here a weir is more commonly used).

Interplant Flows

Parshall Flumes can also be found around the plant itself measuring inter-basin flows.  They are also used for proportional flow splitting at some facilities.

Materials

In North America, Parshall Flumes at wastewater treatment plants are almost always made out of fiberglass.  Fiberglass provides excellent corrosion resistance to hydrogen sulfide and other corrosive agents found in the plant, is light weight, easy to install, and dimensionally stable. 

Outside the North America, it is not uncommon to see treatment plant flumes made out of stainless steel.