TP24-16 Toward Phosphorus-Neutral Cooling Tower Treatment Using Carbon-Negative Environmentally Friendly Additive

The “Stabilized Phosphate” category of cooling water treatments has become an industry standard since the banning of chromate inhibitors in the late 1970’s. They combine good performance, moderate cost and a reasonable environmental profile. However, these programs have their limitations. They represent a balancing act between adequate mild steel corrosion inhibition and calcium phosphate scaling. They also represent a significant environmental liability because of the relatively high inorganic phosphate content which contributes to eutrophication of water supplies. Other ingredients such as MoO₄^-_, Sn⁺², or Zn⁺² are often added to bolster corrosion inhibition and more advanced polymer technology extends the solubility limits of calcium phosphate. However, these measures introduce environmental and economic costs. A new carbon negative, environmentally friendly organic inhibitor is now available which can expand the application profile of stabilized phosphate programs in various dimensions, at modest cost and without environmental baggage. With further development a “Phosphorus-Neutral” program which operates without adding to the phosphorus already in the environment appears to be feasible. Laboratory and pilot testing data are presented to demonstrate the effectiveness of this approach.