What is slow sand filtration?
Water is passed through a layer of fine sand at a slow rate of 4 to 5 meters per day. When water is passed slowly, microorganisms in the sand layer decompose and remove suspended solids in the water. At the same time, bacteria and unpleasant smells are also removed.
This method artificially reproduces what is done in nature. It does not use chemicals, is a nature-friendly water purification method, and can produce good-tasting water.
However, this method requires a large filtration pond, which requires a large area of land. Also, when it rains, river water becomes muddy. In such cases, the system may not produce clear water. To improve the quality of drinking water, we recommend the use of a membrane filtration system in combination with such a system.
Key Points for Slow Sand Filtration
1. use sand with a particle size of 1-2 mm in diameter for the sand filtration layer to allow water to pass slowly
2. a minimum of four ponds or tanks: raw water reservoir, sedimentation pond, sand filtration pond, and post-purification water storage tank
3. install a sedimentation tank and fill the sand filtration layer with clean water to some extent
4. include as much air as possible in the water to activate microorganisms.
5. it takes about 1-2 months to grow the microorganisms needed to break down impurities