Cooling water treatments containing zinc are being more strictly
regulated. Fines are being imposed in some instances where zinc discharge concentrations are as low as 0.5 ppm (mg/L). With regulatory concerns looming, many plants are deciding to eliminate zinc from their cooling loops. Laboratory work was conducted to identify potential zinc replacement technology for use under mill supply conditions typical of those found in pulp and paper applications. This industry segment is one of tbe largest users of once-through cooling water. An organic
replacement able to provide zinc-like performance under mill supply conditions was identified. This paper describes the laboratory protocols utilized to identify this organic material and further develop its use in oncethrough cooling water applications. Case histories are also presented.
Keywords : mill supply, once-through, corrosion inhibitor, deposit control, scale, sequestration, hydroxylated carboxylic acid, pulp and paper.