Steel manufacturer conducts engineering study on water treatment

US Steel was interested in significantly reducing the generation of hazardous waste from its finishing operation in Portage, Indiana. Recently, its cyanide-based plating solution was replaced with an MSA-based bath at the tin mill. This left chromium as the sole hazardous waste constituent generated from the plant. Also, a new acid pickle recycling service was installed, which affected the chromium waste treatment process. This change required the steel manufacturer to purchase chromium reduction chemicals at an annual cost in excess of $300,000/year. The treatment chemicals reduced the hexavalent chromium to a trivalent form, which was then precipitated at the chrome waste treatment plant. The resulting 35 million lb/year of hazardous chromium sludge was disposed of on-site at a captive land fill. A planned new treatment plant maintained the status quo and didn’t offer any benefits, such as elimination of hazardous waste generation via chromium recovery or water recycle. Waste treatment and disposal costs were approximately $1.8 million/year and didn’t include the manufacturer’s corporate environmental liability for potential cleanup of the landfill.

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