According to different sources, wastewater can be divided into two categories: domestic wastewater and industrial wastewater.
Domestic sewage: Wastewater produced by people in their daily lives.
Industrial wastewater: wastewater discharged during industrial production.
(1) Solid pollutants: Solid pollutants are usually expressed by suspended solids (SS) and turbidity.
Turbidity: A measure of the transparency of water. Refers to the scattering of light by particles contained in an aqueous solution.
(II) Organic pollutants: It is mainly described by indicators such as biochemical oxygen demand (BOD) and chemical oxygen demand (COD).
(III) Nutrient pollutants: mainly nitrogen and phosphorus compounds (NH3-N, TP) cause eutrophication
(4) Acid and alkali pollutants: mainly caused by acid and alkali discharged from industrial wastewater and acid rain. The water quality standard uses the pH value to reflect its content level.
(5) Toxic pollutants: The poisons in wastewater can be divided into three categories: inorganic chemical poisons, organic chemical poisons and radioactive substances.
Inorganic chemical poisons: Inorganic chemical poisons include metal and non-metallic types.
Organic chemical poisons: Most of these poisons are synthetic organic substances, which are difficult to be biochemically degraded. They are mainly pesticides (DDT, organochlorine, organophosphorus, etc.), phenolic compounds, polychlorinated biphenyls, polycyclic aromatic hydrocarbons (such as benzopyrene ), Aromatic amino compounds, etc.
Radioactive material: Radioactivity refers to the material properties of nuclear radiation that release radiation.
(6) Oil pollutants: including "petroleum" and "animal and vegetable oil".
(7) Biological pollutants: Biological pollutants mainly refer to pathogenic microorganisms in wastewater, which include pathogenic bacteria, disease eggs and viruses. Hygienic indicators in water quality standards include total bacteria and total E. coli groups.
(8) Sensory pollutants: Substances in waste water that can cause phenomena such as abnormal colors, turbidity, foam, and malodor. Although there are no serious hazards, they can cause extreme unpleasantness in the senses of people. In various water quality standards, corresponding provisions have been made for indicators such as color, odor, turbidity, and floating matter.
(9) Thermal pollution: The harm caused by the high temperature of wastewater is called thermal pollution.