slow sand filtration

Slow sand filtration is a water purification process that uses a layer of fine sand to remove contaminants. As water passes slowly through the sand, natural biological and physical mechanisms work together to trap dirt, bacteria, and algae. A thin, biological layer called a "schmutzdecke" forms on the surface, enhancing the removal of pathogens. This method is effective, low-cost, and environmentally friendly, making it ideal for small communities or areas with limited resources. Over time, the sand is cleaned or replaced to maintain its effectiveness.