File Name: slow sand filter and rapid sand filter .zip
Many water treatment plants use a combination of coagulation, sedimentation, filtration and disinfection to provide clean, safe drinking water to the public. Worldwide, a combination of coagulation, sedimentation and filtration is the most widely applied water treatment technology, and has been used since the early 20th century. For more information about the disinfection portion of the treatment process, see the Chlorination fact sheet. The coagulation process involves adding iron or aluminum salts, such as aluminum sulphate, ferric sulphate, ferric chloride or polymers, to the water.
Slow Sand Filtration
Department of Agriculture, and are one of the top potted flowering plants in the United States Dole and Wilkins, In the greenhouse production of floriculture crops, recirculating irrigation systems have been widely adopted to lower water usage and conserve fertilizers that can otherwise be lost via discharge runoff Bush et al. This is especially true for greenhouses with large water use [1. Ebb-and-flow and flood-floor irrigation systems typically recirculate the irrigation water and are used to maximize production area and decrease labor costs Ehret et al. In this type of system, irrigation water is pumped from a water reservoir to flood the floor or bench at a specified water level for a desired duration, and then drained back often by gravity flow to the reservoir for recycling in the next irrigation event.
Sand filtration: rapid versus slow
A slow sand filter is a sand filter adapted for household use. Please note that although commonly referred to as the BioSand Filter External , the BioSand Filter terminology is trademarked to one particular design, and this page encompasses all slow sand filters. The version most widely implemented consists of layers of sand and gravel in a concrete or plastic container approximately 0. The water level is maintained to cm above the sand layer by setting the height of the outlet pipe. This shallow water layer allows a bioactive layer to grow on top of the sand, which contributes to the reduction of disease-causing organisms. A diffuser plate is used to prevent disruption of the biolayer when water is added. To use the filter, users simply pour water into the top, and collect finished water out of the outlet pipe into a bucket.
Some rapid sand filters also contain a thin layer of garnet sand. This layer also tends to improve filter performance. Filters with a layer of garnet sand are referred to.
How To Make A Rapid Sand Filter
The filtration through sand is achieved by mechanical, physical and biological principles. The share of each of these processes during filtration depends on the flow rate of water in the filter and the presence of microorganisms. Due to the construction and water flow speed sand filters are divided into two basic groups: slow and rapid.
There are two main types of sand filters that are used for water treatment: rapid sand filters also known as Rapid Gravity Filters or RGFs and slow sand filters. Sand filters should not be confused with Roughing Filters, which tend to be horizontal-flow gravel filters used as a roughing treatment for turbid raw waters prior to sand filtration. The two sand filtration processes differ from each other in several ways. In general however, rapid sand filters are usually fully automated, complex and costly, forming part of a wider treatment process in industrialized countries. They are not known to be suitable for household-level use, as is the case with versions of the slow sand filter, for example the intermittently operated slow sand filter or IOSFF.
Rapid vs slow filtration - Biosand filter. Rapid sand filtration is a purely physical drinking water purification method. Rapid sand filters RSF provide rapid …. In general, rapid sand filters use sand with an effective size of 0.