Successful antiscalant field trial — Optimization at higher pH and seawater temperature, Larnaca desalination plant

Abstract

Larnaca Desalination Plant (LDP) has lead the way in operating for a number of years at elevated pH both at the first and second Reverse Osmosis (RO) stages at higher feed sea water temperature up to 30 °C. The main reason for the higher pH was to enhance the boron rejection capability of existing membranes and thus reduce the need for a second stage at lower sea water temperatures and subsequently produce more water at less energy. However, higher pH in conjunction with high sea water temperatures create conditions for membrane scaling. Therefore an appropriate cost effective antiscalant has to be used with minimum dosing rate. This article describes field trials of choosing and applying an appropriate antiscalant and dosing optimisation as a function of feed sea water temperature and pH.

Keywords:

• Boron removal
• RO
• high pH