Rocks filter water primarily through two main mechanisms: introducing oxygen to precipitate iron and acting as physical barriers to trap sediment.
Here's a breakdown:
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Oxidation and Precipitation: Rocks, especially lava rocks, facilitate the oxidation of iron present in the water. This process causes the iron to react with oxygen and form rust (iron oxide), which then precipitates out of the solution as solid particles. These particles can then be physically filtered out.
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Physical Filtration: Rocks, along with other materials like sand and gravel often used in water filters, act as physical barriers. Larger rocks filter out larger particles, while smaller rocks and sand filter out finer sediments, dirt, and debris. The water passes through these layers, leaving the impurities behind.
In short, rocks improve water quality by oxidizing dissolved iron and physically trapping sediment.
