Table of Contents
What is effluent weir?
[ə′flü·ənt ′wer] (civil engineering) A dam at the outflow end of a watercourse.
What is a weir in wastewater treatment?
weir (WEER) A wall or plate placed in an open channel and used to measure the flow of water or to control flow (from settling tanks and clarifiers) to ensure a uniform flow rate and avoid short-circuiting. Also see proportional weir.
What is effluent launder?
Typically, raw sewage is fed into one or more clarifiers in which heavy solids settle out of suspension by gravity. Water (minus the heavy solids) flows over a V-notch weir and cascades into a trough (called an “Effluent launder”) which surrounds the clarifier.
What is the purpose of primary clarifiers and/or grit settling tanks?
Suspended solids that pass through screens and grit chambers are removed from the sewage in sedimentation tanks. These tanks, also called primary clarifiers, provide about two hours of detention time for gravity settling to take place. As the sewage flows through them slowly, the solids gradually sink to the bottom.
What is the purpose of sedimentation tank?
A sedimentation tank allows suspended particles to settle out of water or wastewater as it flows slowly through the tank, thereby providing some degree of purification. A layer of accumulated solids, called sludge, forms at the bottom of the tank and is periodically removed.
What purpose do weirs serve?
Weirs create a barrier across the river that can adversely affect wildlife (especially fish) and recreation. Appropriate design can ensure that the adverse impacts are minimised or eliminated, or even turned into a benefit.
What is the purpose of V notch and rectangular weir?
To conserve delivery head and reduce head loss, the rectangular and wide V-notch weirs rated by Kindsvater methods should be selected. These weirs provide the capability to use shorter heights from the approach channel invert to the crest.
Why must algae growth be removed from clarifier weirs launders and troughs?
Sludge density and effluent clarity. Why must algae growth be removed from clarifier weirs, launders, and troughs? To prevent interference with disinfection and permit compliance.
What is weir overflow rate?
The weir overflow rate is the number of gallons of wastewater that flow over one lineal foot of weir per day. The typical WOR range for primary clarifiers is 10,000 to 20,000 gallons per day per lineal foot of weir.
What is the purpose of primary sedimentation tanks briefly explain the factors that influence the sedimentation process?
How are weirs used to control the flow of water?
A weir is a small dam built across a river to control the upstream water level. Weirs have been used for ages to control the flow of water in streams, rivers, and other water bodies.
How is water disinfected at the effluent Weir?
The clarified water flows over the effluent weirs and discharges to the excess flow chlorine contact basin, where the flow is disinfected by sodium hypochlorite and dechlorinated with sodium bisulfite. As plant flow increased, however, the ferric chloride floc tended to rise over the effluent weirs.
What does the term Weir mean in engineering?
Over time, the term weir has taken on a more general definition in engineering to apply to any hydraulic control structure that allows water to flow over its top, often called its crest. In fact, the spillways of many large dams use weirs as control structures.
What happens to a weir during a flood?
With a passive structure and fixed rating curve, that variability in flow means tremendous variability in the water level upstream. During a flood, a weir may back up the water badly enough to cause damage upstream.