CPI - No Longer Singing the Blues

Composite valves incorporated into Blue Plains Advanced Waste Water Treatment Plant outperform expectations while helping improve operations

Nil-Cor 310 series ball valve

The Blue Plains Advanced Wastewater Treatment Plant, operated by the District of Columbia Water & Sewer Authority (WASA), is the world’s largest advanced wastewater treatment facility.

The Blue Plains facility treats wastewater from two million people and a large number of businesses located in a service area that includes the District of Columbia and major portions of Maryland’s Montgomery and Prince George Counties, and Virginia’s Fairfax and Loudoun Counties.

The Blue Plains Advanced Wastewater Treatment Plant’s total plant capacity exceeds a billion gallons of water a day. Its National Pollutant Discharge Elimination System (NPDES) permit requires peak full treatment flow rates of 740 mgd for up to four hours and continuous full treatment flow of 511 mgd. In addition, up to 336 mgd storm water flow must receive partial treatment. According to the plant’s officials, these levels of required treatment are some of the most stringent in the US.

Ultimately, treated wastewater is discharged into the Potomac River. Organic bio-solids generated from treated solid waste are applied to agricultural land in Maryland and Virginia.

The Blue Plains Advanced Wastewater Treatment Plant has undergone a 10 year, billion dollar programme to ensure compliance with its NPDES permit requirements.

Valve Malfunction

Even before the massive plant upgrade began, existing control valves were not properly functioning. PVC valves were in use for chemical applications at WASA, and these valves were not sufficiently robust for the applications. A major problem, particularly with older valves, was that the valve operators would break off when the valves were being turned. Even on new valves, it wasn’t unknown for the valve operator to break the first time that the valve was used, and when workers are trying to divert chemicals from one line, or tank, to another, a failure can create a leak and cause problems. When the backup valve also fails, the problems are compounded.

After a valve failure that involved chemicals, WASA began to search for a valve that would solve their problems. One of their contractors contacted Nil-Cor. Nil-Cor ball valves, which were described as being “substantially beefier” that the existing PVC valves, were installed on chemical lines, including sodium hypochlorite, in a variety of areas in the plant. Both lever and actuated valves were tested for between 6 and 12 months.

New Valve Passes Test

Following successful testing WASA proceeded to install Nil-Cor series 310 & 410 series glass fibre reinforced flanged ball valves in a number of applications throughout the plant, including its disinfection facilities and chemical buildings.

In the course of upgrading the plant, WASA wanted to alleviate vital chemical handling and safety concerns. Liquid/gaseous chlorine and sulphur dioxide were delivered to Blue Plains in 90-ton rail cars for use in disinfection and de-chlorination operations. The plan was to use less volatile chemicals, liquid sodium hypochlorite and liquid sodium bisulphite. Nil-Cor valves were installed in any area where corrosive chemicals are being used. WASA are comfortable that the valves work, and help alleviate serious hazards in the plant.

The Nil-Cor 410 Polysulfone valve, designed and manufactured specifically for sodium hypochlorite and caustic applications was specified for WASA chemical installations, and was described as being, “durable, heavy duty, chemical resistant, high quality & well built.”

Nil-Cor valves are distributed in the UK & Eire by CPI Group.

CPI (Pneumatics) Ltd
Tel: 01623 510245
Website: www.cpisystems

Published in Valve User Magazine Issue 19

Summer 2020 // Issue 53
Read latest articles Pageflip Magazine Version Download Magazine