However, sludge from the flocculation chambers may cause pollution if not properly disposed of. This technology provides high quality water, and is a proven method for large-scale water supply. The technology is expensive to operate. The technology is effective in polishing raw water to produce pathogen-free potable water. Slow Sand Filtration Technical Description Raw water is filtered through a sand bed made of uniformly graded sand overlying a gravel bed.
Treatment occurs through physical, biological and chemical processes.
This technique is widely used in rural areas of Africa. Operation and Maintenance Minimal maintenance is required. Level of Involvement Use of this technology requires few technical skills. Costs Costs of construction and operation are reasonably low. Suitability Slow sand filtration is suitable for small settlements.