Where are slow sand filters used?

Slow sand filters are used in water purification for treating raw water to produce a potable product. They are typically 1 to 2 metres deep, can be rectangular or cylindrical in cross section and are used primarily to treat surface water.

What are the basic difference between between slow sand and rapid sand filters?

Difference between Rapid sand filter and slow sand filter

Item	Slow sand filter	Rapid sand filter
Under drainage system	Laid to receive filtered water Open joint pipes.	Laid to receive filtered water and also to pass backwash water at a higher rate. Manifold and latarals.

What is the rate of filtration in slow sand filter?

100 to 200 liters per hour
Note:

Characteristics	Slow Sand Filters	Rapid Sand Filters
Rate of filtration	Low, typically ranges 100 to 200 liters per hour per sq. m of filter area.	High, typically ranges 3000 to 6000 liters per hour per sq. m of filter area.

What are the advantages of a sand filter?

What are the advantages of a sand filter?

• Various floating particles can be removed.
• Deferrisation, demagnisation and ammonia can be removed.
• Reduction of protozoa and bacteria.
• Easy to operate and low maintenance requirements.
• Effective removal and long lifetime.

How much is the capacity of slow sand filter to remove the bacteria?

Slow sand filters can reduce water turbidity to less than 1 NTU, total organic content by 10\%, remove 95\% of coliform bacteria, improve a water’s color, taste, and odor, and do not result in significant sludge production.

What is a ‘slow sand filter’?

‘Slow’ sand filters are so called because the rate of filtration through them may be only one twentieth or less of the rate of filtration through rapid gravity or pressure filters. Most of London’s surface derived supplies are treated by slow sand filters although a number of less efficient works have been closed down.

What is sedimentation and clarification in filtration?

Sedimentation and Clarification. Sedimentation is the next step in conventional filtration plants. (Direct filtration plants omit this step.) The purpose of sedimentation is to enhance the filtration process by removing particulates.

Is slow sand technology the future of surface water treatment?

With the recent issuance of the Surface Water Treatment Rule by the U.S. Environmental Protection Agency and new filter requirements for all surface water systems to ensure removal of Giardia cysts, there is renewed interest in slow sand technology.

What is the most common filtration process?

The most common filtration process employs a granular media (e.g., sand, anthracite coal). Filtration is usually a combination of physical and chemical processes. Mechanical straining removes some particles by trapping them between the grains of the filter medium (such as sand).