Steel industry.
D000497:Alloys; D005160:Facility Design and Construction; D005374:Filtration; D007220:Industrial Waste; D007501:Iron; D008669:Metallurgy; D008722:Methods; D012498:Sanitary Engineering; D014876:Water Pollution; D014877:Water Pollution, Chemical; D014881:Water Supply
D000497:Alloys; D007220:Industrial Waste; D007501:Iron