Which physical characteristic helps in the removal of certain microorganisms from drinking water?

The size of three to seven microns is significant in the context of water treatment because it pertains to the physical filtration processes used to remove microorganisms from drinking water. Many pathogenic microorganisms, including some bacteria and protozoa, fall within this range. This size is crucial because physical barriers, such as filters, can effectively trap and remove these organisms, thus improving the safety of drinking water.

Additionally, this size characteristic aligns with filtration methods that target particles in this dimension. Microfiltration and ultrafiltration techniques often utilize materials that can efficiently capture particles within this range, ensuring that harmful microorganisms do not pass through the filtration system. By removing these microorganisms, water treatment processes can significantly reduce the risk of waterborne diseases.

Other factors like color changes, odor detection, and pH levels may indicate water quality issues but do not directly contribute to the removal of microorganisms in the same tangible way as effective physical size-based filtration does. They may assist in identifying contaminants or issues in the water but do not serve as mechanisms for microorganism removal in the filtration process.