Filter Designed

Filter Designed

What is Rapid Sand Filter?

Rapid Sand Filter

The rapid sand filter is a type of filter commonly used in municipal water treatment facilities.

Rapid sand filters use relatively coarse sand and other granular media to remove particles and impurities that have been trapped in a floc through the use of flocculation chemicals - typically salts of aluminium or iron. Water and flocs flows through the filter medium under gravity pressure and the flocculated material are trapped in the sand matrix.

Rapid filters are usually built open with the water passing down the filter but by gravity. It has a filter rate of 4 – 8 m3/m2/hr. The tank is made of concrete with a depth of 3.0 to 3.5m. Coarse sand of size 0.4 to 1.5mm is used as the filter medium. The rapid sand filter or rapid gravity filter is a type of filter used in water purification and is commonly used in municipal drinking water facilities as part of a multiple-stage treatment system.[1] Rapid sand filters were first used in the United States in 1896 and were widely used in large municipal water systems by the 1920s, because they require smaller land areas compared to slow sand filters. Design and operation

Rapid Sand Filter use relatively coarse sand and other granular media to remove particles and impurities that have been trapped in a floc through the use of flocculation chemicals--typically salts of aluminium or iron. Water and flocs flows through the filter medium under gravity or under pumped pressure and the flocculated material is trapped in the sand matrix. Mixing, flocculation and sedimentation processes are typical treatment stages that precede filtration. Chemical additives, such as coagulants, are often used in conjunction with the filtration system. Maintenance Rapid sand filters must be cleaned frequently, often several times a day, by backwashing, which involves reversing the direction of the water and adding compressed air. During backwashing, the bed is fluidized and care must be taken not to wash away the media.

Advantages and Disadvantages

Rapid Sand Filter are typically designed as part of multi-stage treatment systems used by large municipalities.

These systems are complex and expensive to operate and maintain, and therefore less suitable for small communities and developing nations.

Advantages Much higher flow rate than a slow sand filter; about 150 to 200 million gallons of water per acre per day Requires relatively small land area Less sensitive to changes in raw water quality, e.g. turbidity Disadvantages Requires greater maintenance than a slow sand filter. For this reason, it is not usually classed as an "appropriate technology," as the term is applied in less-developed countries. Generally ineffective against taste and odour problems. Produces large volumes of sludge for disposal. Requires on-going investment in costly flocculation reagents.

The Rapid Sand Filter (RSF) differs from the Slow Sand Filter in a variety of ways, the most important of which are the much greater filtration rate and the ability to clean automatically using backwashing.

The mechanism of particle removal also differs. RSF does not use biological filtration and depends primarily on mechanical straining, sedimentation, impaction, interception, adhesion and physical adsorption. In RSF the complete filtration cycle (filtration and back washing) occurs sequentially. Filters that must be taken off-line periodically to back wash are classified operationally as semicontinuous. Filters in which filtration and backwash operations occur simultaneously are classified as continuous.

About the Author

Shubham is the leading Indian water and wastewater Treatment Company providing the most comprehensive water and waste water treatment systems and services for industrial, institutional and municipal customers. Through a pioneering approach in water and waste water treatment, Shubham works to service its clients through a holistic approach.

For More Details : www.shubhamindia.com

Is Al Gore perfecting a charcoal filter for the seat of your pants designed to reduce greenhouse gas emissions?

We will all be required to purchase them from Al Gore or we will be fined by the IRS

Al Gore loves his monopolies. First it was the Al Gore monopoly on trading carbon credits, now this.

Nano tank Canister filter