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Steelmaking. The exhaust gas cleaning and cooling wastewater is the largest volume of wastewater generated.
Each of the three types of furnaces generate different wastewater volumes and pollutant characteristics. Semiwet
systems generate less wa~tewater because the systems use less water. Wet-suppressed combustion system
wastewater is lower in suspended solids than wastewater from the wet-open combustion system. Solid wastes
cunsists uf slag, in-plant scrap and furnace Ilue dust and sludges.
Forming - Wastewaters from descaling, roll cooling, equipment cooliDg, roll tables, and flume flushing are
generally discharged through trenches, called flumes, beneath the rolling mill to inground concrete or steel
chambers called scale pits. These scale pits act as sedimentation tanks where the heavier solid particles settle
out. Untreated wastewater from hot forming operations contain significant levels of suspended solids and oil
and grease. Toxic metal pollutants are present in lesser concentrations.
Pollutanlc; generated by the iron and steel industry include Suspended Solids (S5), oil and grease, ammonia, and
metals (iron, zinc and lead), cyanide and phenol. Other metals, inorganic and organic compounds may be
present in low concentrations.
4.3 \Vnstewater Discharge Guidelines
Several cuuntries have established environmental regu1:Jtions that apply to the wastewater discharge from the iron
and steel industry. The regulations for Turkey, Japan, Germany, and the USA are presented in Attachment B.
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