On March 15, 2022, the national "Hygienic Standard for Drinking Water" GB5749-2022 was released, replacing the original GB5749-2006. The new national standard has adjusted the indicators from the original 106 to 97 items, with 4 new indicators added: geosmin (10ng/L), 2-methylisoborneol (10ng/L), acetochlor (0.02 mg/L), and chlorate (0.7 mg/L).

Urban domestic sewage mainly originates from daily residential water use, including wastewater from washing, bathing, and kitchen and toilet drainage. It contains pollutants such as organic matter, nitrogen and phosphorus nutrients, suspended solids, and pathogenic microorganisms.

Scale formation in industrial recirculating water refers to the precipitation of salts such as calcium and magnesium from the water due to increased temperature, changes in pH, or evaporation concentration, resulting in the formation of hard deposits on the surfaces of pipes, heat exchangers, and other equipment. Common types of scale include calcium carbonate, calcium sulfate, and silicates. Scale buildup can reduce heat transfer efficiency, increase energy consumption, and even clog pipes, affecting the normal operation of the system. Control methods include water softening, adding scale inhibitors, adjusting pH levels, and regular descaling.