The basic principle of water treatment equipment is to remove or transform impurities, harmful substances, or dissolved pollutants in raw water through a combination of physical, chemical, and biological methods, bringing it up to meet usage or discharge standards. Different processes operate on different principles:
Physical Treatment: Primarily relies on filtration, sedimentation, and interception to achieve separation. For example, sand filtration and activated carbon filtration use particulate media to adsorb or intercept suspended solids; microfiltration, ultrafiltration, and reverse osmosis utilize the selective permeability of membranes to achieve fine separation of water molecules and pollutants. This process does not change the properties of the pollutants but removes them through physical barriers.
Chemical Treatment: Achieves pollutant transformation or removal through reactions. For example, coagulation processes use chemicals to aggregate colloidal particles into flocs for easy settling; oxidation processes (such as ozone and chlorine disinfection) can destroy the structure of organic matter or kill microorganisms; ion exchange uses resins to exchange calcium and magnesium ions in the water, achieving softening or desalination. These methods emphasize chemically driven water quality improvement.
Biological Treatment: Primarily relies on the metabolic degradation of pollutants by microorganisms, such as the activated sludge process or the Membrane bioreactor process. Microorganisms convert organic pollutants into carbon dioxide, water, and other stable substances, thus achieving the harmless treatment of pollutants. This method is widely used in the treatment of domestic sewage and organic industrial wastewater.
In summary, the core principle of water treatment equipment is to achieve the step-by-step removal of pollutants in different forms through a combination of technologies, gradually transforming the water quality from "raw water" to "usable water or compliant discharge water."