1. Characterization of industrial wastewater

The term "industrial wastewater" refers to all water that is normally discharged by the factory into the external environment after being used in manufacturing, cleaning, transport, cooling, etc., generally excluding rainwater unless it is polluted by runoff from factory roofs causing significant air pollution (e.g., cement plants, thermal power plants, etc.) or from the soil of active or abandoned industrial sites contaminated by various substances (nitrogen compounds, hydrocarbons, metal salts).