Table 1.

Classification, main effluents, and characteristics of wastewaters from the metallurgical industry

Water source	Main effluents	Types of wastewater	Wastewater characteristics
Iron and steel industrial wastewater	Heavy metals Aromatic compounds Surfactants Cyanides Fluorides (Sathya et al. 2022)	Process (Raw material system, coking, sintering and pelletizing, iron smelting, steelmaking and continuous casting, hot/cold rolling) (Wu et al. 2017b).	Physical characteristics Temperature, turbidity, total suspended solids, color, and odor (Zhuang et al. 2019)
		Integrated (Wu et al. 2017b).	Chemical characteristics Chemical oxygen demand (COD), total organic carbon (TOC), heavy metals, dissolved oxygen (DO), toxic substances, pH, phosphorus, sulfur, chlorides, and other trace elements.(Zhuang et al. 2019).
Non-ferrous metallurgical wastewater	Copper, lead, and zinc) and xanthate (S. Meng et al. 2022) Arsenic and cadmium (Qi et al. 2023)	Heavy, light or rare earth non-ferrous metallurgical wastewater (P. Wu et al. 2017b).	Biological characteristics Biochemical oxygen demand (BOD), as well as microbes like bacteria, viruses, parasites, and the oxygen required for nitrification and microbial populations (Zhuang et al. 2019).
		Acidic, alkali, heavy metal, fluoride, cyanide, oil-containing or radioactive wastewater (Wu et al. 2017b)