Keywords: seawater desalination, horizontal boreholes, seawater intake, reverse osmosis, brine discharge, pretreatment, ocean intakes
Innovative seawater intake for reverse osmosis desalination plants
Seawater desalination plants typically consist of four major unit operations: seawater intake, pretreatment, Reverse Osmosis (RO) stage, and posttreatment and brine discharge. The best way is to go through vertical beach wells, but the increase of the production capacity of the plants built in recent years makes open intake the only solution. These open ocean intakes draw seawater through the meshed intake screen and then convey the seawater to the desalination plant. The raw seawater then undergoes pretreatment, typically using either conventional or membrane pretreatment processes to prevent particle/colloidal fouling of Reverse Osmosis/Nanofiltration (RO/NF) membranes. Use of these pretreatment processes increases the capital cost of the facility and also escalates the operational costs, as these facilities require additional chemicals and energy. For these reasons, an alternative has arisen in recent years, namely horizontal boreholes. The present paper analyses this option and compares its performance in a real case study.