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• Increasing the frequency of iron oxide rcmoval in the scale pits within the
rolling mill.
• Hydraulic Fluid Leak Reduction - Reduce the quantity of hydraulic oil in the cooling
water with improved maintenance (both preventive and corrective programs) of the
equipment to prevent or correct hydraulic fluid leaks.
• Good Housekeeping - Emphasize practices that maintain a clean work place without
the use of water for cleaning. Preventing spills and leaks reduces clean-up. When
spills or leaks occur, clean-up should be conducted using dry methods such as
absorbents or a mobile vacuum cleaner that captures the spill rather than diluting the
spill with washwater.
Other PP/WM techniques that should be investigated for feasibility studies and possible
short- and long-term implementation are listed below:
• Rolling Mill Wastcwatcr Tre;1tmen( Dcsi(;n Modifications - Dc.c;ign modifications to
the wastewater treatment system to achieve the water quality necessary to enable
complete recycle (ar 95 percent recycle) of the cooling water. An engineering
analysis of the following modifications should be conducted:
• Leveling the weirs in the sedimentation tanks to prevent 'short-circuiting;
• Installing automatic oil skimming devices and/or oil/water gravity separator;
• Replacing the 4-chamber sedimentation tank with a high efficiency clarifier
design, such as tube settlers, inclined plate clarifiers, or clarifiers with
continuous sludge removal; and
• Installing sand filtcrs or other sllspentlco solitls treatment such as
J11 iemfi Itrati on.
• Softcncr Rcgcneration - Use a regencration chemical that is less harmful to the
environmcnt, sllch as acetic acid ano ammonium hyoroxide to reduce the high
concentrations of sotlium and chloride salts in the wastewater.
• Softener Upgrading - Use a newer state-of-the-art ion-exchange resin system that is
regenerated with less solution and therefore generates a smaller volume, more
concentrated wastewater.
• Cooling Water Treatment - Use ozone rather than biocide chemicals to control
fouling in the cooling towers.
• Cooling Water Segregation - Segregate the contact cooling water for the continuous
casting operation from the softened non-contact cooling water for the furnace. Reuse
rolling mill cooling water or treated blowdown water. Treat the cooling water
through the hydrocyclone and sand filters and recycle directly back to continuous
E5
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