Use of recycled water in cooling towers presents a unique challenge with conflicting goals and characteristics. Ideally, cooling towers evaporate water resulting in two to six cycles of concentration of minerals before a significant portion (17-50%) of the water must typically be discharged to waste treatment plants. The cycles of concentration (COC) varies based on the concentration of minerals which cause scale and corrosion of metals. A new “green” technology, that uses simple filtration and ion-exchange (softened) pretreatment of recycled cooling tower makeup water, was been implemented at a US automotive corporate headquarters. The filtering and softening treatment permit the recycled water to be used at dramatically increased TDS levels. As cycles increase several benefits are derived: • Silica, naturally present in the water, converts to a corrosion inhibitor eliminating the need for chemical corrosion inhibitors The effect of silica-azoles (TTA) treatment for inhibiting corrosion of copper, zinc and aluminum in zero blow-down, high TDS, soft tower water containing ammonia was evaluated. Corrosion inhibition performance was excellent for copper, aluminum, and zinc with the combination of silica and TTA inhibitors while exposed to ammonia in both laboratory studies and tower study test results. CMAS measurements indicate that silica inhibitor reduced localized corrosion.

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• Water Conservation Technology International

• West Basin Municipal Water District

• Cooling Tower

• Recycled Water

• Water Treatment

• Corrosion

• Recycled Water

• Silica Scale

• Article