On our planet, water is the cradle of life. However, not all water is suitable for life to draw directly. Water purification has thus become a crucial mission in modern society to safeguard the source of life.

The process of water purification is like a meticulously arranged magic show. Starting from the water source, raw water carrying silt, impurities and microorganisms flows slowly. First of all, the sedimentation process comes into play. In large sedimentation tanks, the water seems to be paused. Larger particles like silt gradually settle down under the pull of gravity and are initially separated from the water. This process is based on the principle of gravitational settling in physics. Particulate matter settles to the bottom because its own gravity is greater than the buoyancy force exerted on it by the water.

Subsequently, the filtration devices play a significant role. Sand filter layers, activated carbon filter layers and so on are just like fine filters, intercepting tiny suspended particles. Sand filtration mainly relies on the tiny pores among sand grains. When water flows through, suspended particles are retained because they cannot pass through these pores. Activated carbon has a unique porous structure, and its huge specific surface area enables it to effectively capture odor molecules and some organic pollutants in water through physical adsorption, making the water start to become clear, transparent and free of unpleasant odors.

As for harmful substances such as dissolved salts and heavy metals in water, reverse osmosis technology is a powerful tool. Reverse osmosis technology is based on the principle of semi-permeable membranes. Driven by pressure, only water molecules can pass through the semi-permeable membrane against the osmotic pressure, while salt ions and heavy metal ions are retained by the selective blocking of the membrane, thus obtaining highly purified water. For example, in seawater desalination, reverse osmosis membranes can block a large amount of sodium chloride and other s