Check Valves Provide Better Diffusion Value on the Sea Floor

Proco designed, engineered duckbill diffusers to accommodate outfall sewage from Istanbul treatment plant.

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The Water Authority of Istanbul, which owns a biological wastewater treatment plant, serves a population of about 15 million people in the city of Istanbul, Turkey.

Marine Consultant Group (MCG) worked with Proco Products to design and engineer duckbill diffusers to accommodate outfall sewage from the treatment plant through an 87-inch-diameter steel pipe that extends 1.35 miles (2,230 meters) along the bottom of the ocean and discharges at about 154 feet below sea level.

There were several challenges Proco needed to keep in mind for this project. One concern was that diffusers and duckbill check valves might be damaged by passing marine vessels. To address this, Proco needed to determine the appropriate diffuser length, which in this project was about 741.5 feet at the furthest end of the 1.5-mile run on outfall pipe.

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An 87-inch-diameter steel pipe extends 1.35 miles along the bottom of the ocean and discharges at about 154 feet below sea level in Istanbul..

Each port discharge was equipped with two 10-inch diameter (250 mm) duckbill check valves. The ProFlex 710 duckbill check valves provided several advantages: There was no need to blind cap some of the ports during the first years of operations and it eliminated the need to blind flange ports since the lines can operate with full efficiency from initial startup, reducing diver time and decreasing maintenance.

In addition, the duckbill check valves’ highly engineered elastomer maintains its memory after long periods of staying open or closed. The elastomeric check valves are also 100 percent barnacle- and algae-resistant.

The system has been a fully functional success and Proco continues to offer assistance and engineering expertise on systems comparable to this on a global scale. WW

Proco is exhibiting at WEFTEC.18, booth 3118. For more information, visit

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