Slow Sand Filtration is an Effective Method of Water Purification
When it comes to an effective method of purifying water for multiple uses, sand filter systems always come to mind. These systems use a layer of sand and other components to slowly filter out contaminants from a water sample. One of the most effective sand filtering techniques is slow sand filtration (SSF). SSF uses a filter to remove pathogens and turbidity all in a single step.
SSF is effective enough not to require any pre-treatment steps (unless there is a high presence of sedimentation and algae content in the water). As a result, slow sand filtration is highly reliable and can be carried out at a relatively low cost. It has the potential of revolutionizing small and medium-sized water filtration methods in rural communities.
In these areas, fresh water tends to be in relatively abundant supply but is mostly contaminated. Sand filter systems therefore pose a useful method of purifying water and making it ready for use in homes.
How it works
The basic concept behind slow sand filtration and other sand filter systems is quite simple. A sample of contaminated water flows through a layer of sand that filters and biologically treats the water as it passes through. During the slow sand filtration process, not only are contaminant sediments removed, but pathogens are also filtered out using microorganisms that are based in the sand.
There is a significant difference between a slow and rapid sand filtration process. In rapid sand filtration, the only process that is being carried out is a physical separation of the components. On the other hand, slow sand filtration is both a physical and biological process.
Biological filtration
The biological process is an essential part of sand filter systems, because harmful microorganisms (in addition to sediments) can be removed from the water during the filtering process. How it works is that the top layer of the sand in the filtering system is essentially turned into a microbial community that is capable of trapping pathogens in the water being purified.
Because the filtering process is slow, the sample water itself is the source of these bacteria, which are able to form in just a few days. The bacteria prey on microbes that are present in the water, thus achieving a self-sustainable filtration process.
The structure of the system
The apparatus that forms a slow sand filtration system is quite simple in its design. It only requires a basic filter chamber, a reservoir to hold the water and sand, and pipes that provide an inlet to and from the chamber. This makes these types of sand filter systems a convenient option for the home.
Share