clarifiers for water treatment?

Question

could some one please breiefly describe the function of major components of an upflow clarifier ??

please help

Answer 1

There is more than one type of upflow clarifier.
The following article describes two types.

The purification process begins at the intake tower, where water flows into one of the tower's four gates, passes through a six-foot tunnel, and enters the pump room in the Lakeside Power Station. There, revolving screens remove fish, leaves and other large debris. It is also at this point that powdered activated carbon is added to remove unpleasant tastes and odors, as well as residual agricultural pesticides.

The water is then pumped to the Purification Plant, where it passes through a chemical dosing chamber to receive lime, which softens the water, and ferrous sulfate (iron) and polymer, both of which coagulate the suspended particles in the water. From the dosing chamber, the water passes to one of five upflow clarifiers.

CWLP currently uses three types of upflow clarifiers. The first is the Spaulding Upflow Clarifer, designed by the utility's first Water Plant Superintendent, Charles Spaulding. For many years, this type of clarifier was considered state-of-the-art and was used by purification plants around the world. In the Spaulding Upflow Clarifiers, water flows downward, through a large inverted cone in the center of the clarifier. At the bottom of this cone, a series of revolving paddles mix the water and chemicals. Then, flowing outward and upward into the main body of the clarifier, the water passes through a blanket of lime sludge formed from an accumulation of coagulated particles. Most of the suspended particles in the upflowing water are trapped there. The cleaned water then flows over the top of the clarifier and heads to the filter gallery.


The second type of clarifier currently being used by CWLP is a Permutit unit, which is simply a modified version of the Spaulding clarifier. The third and newest model, is the Helical Flow Clarifier, designed by another former CWLP Water Plant Superintendent, Dave Wyness. In this type of clarifier, the water is introduced into the base of the clarifer where it moves upward in an ever expanding and slowing spiral motion, passing through the lime sludge blanket on its way. The Helical Flow Clarifier is superior to the Spaulding unit in two ways. First, it has no moving parts and requires no power to operate. Second, it is better at removing suspended particles, producing a better overall water quality. As in the Spaulding Clarifiers, water that has passed through the sludge blanket then overflows the top of the clarifier and heads to the filter gallery for the final stage of purification.


On its way to the filter gallery, the clarified water receives a dose of chlorine to kill bacteria and fluoride to prevent tooth decay.


Each of the 12 two-cell filters in the filter gallery contains a layer each of sand and finely crushed anthracite coal, which screen out additional particles still remaining in the water. These filters are cleaned about every 96 hours by "backwashing" them with 60,000 gallons of water per filter.


From the filter gallery, the clean water is sent to two underground clearwells for temporary storage prior to distribution. At this point, the purification process is complete. It has taken less than two hours to convert raw lake water into a safe, clean product that consistently meets state water quality standards .

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