A novel inhibitor for scale control in water desalination

Abstract

Premature membrane failure and membrane fouling in reverse osmosis and efficiency loss in distillation processes during water desalination are generally the result of mineral scale deposition in critical parts of these processes. The efficiency of multi-stage flash evaporators is compromised by operating at lower temperature than an ideal temperature to reduce scaling problem. A novel compound, polyamino polyether methylenephosphonate (PAPEMP) is an ideal additive for desalination operations because it simultaneously, controls calcium carbonate and calcium sulfate scale formation and deposition. It can reduce or eliminate acid feed, thus limiting the hazards associated with it and lessening equipment corrosion. In acid feed systems, PAPEMP chemistry is very forgiving in the event of over or underfeed of acid. Unlike most other phosphonates, PAPEMP's high tolerance for calcium ions completely avoids membrane fouling with calcium phosphonate salts. The inhibitor is also very effective for controlling silica/silicate deposits and stabilizing hydroxides of iron, demonstrating that PAPEMP is able to overcome all the shortfalls of the current technology used for scale/deposit control in water desalination.