Desalination of Highly Saline Water Using Direct Contact Membrane Distillation (DCMD)

Salah S Ibrahim,Noor A Mohammad Ameen

doi:10.22153/kej.2018.12.005

Abstract

In this work, laboratory experiments were carried out to verify direct contact membrane distillation system’s performance in highly saline water desalination. The study included the investigation of various operating conditions, like feed flow rate, temperature and concentration of NaCl solution and their impact on the permeation flux were discussed. 16 cm2 of a flat sheet membrane module with commercial poly-tetra-fluoroethylene (PTFE) membrane, which has 0.22 μm pore size, 96 µm thickness and 78% average porosity, was used. A high salt rejection factor was obtained greater than 99.9%, and the permeation flux up to 17.27 kg/m2.h was achieved at 65°C for hot feed side and 20°C for cold side stream.

Highlights

The supply and demand for sweet water were progressively increasing throughout the last two decades
Thermal process typically involves saline water boiling or evaporation collecting resultant distillate, examples of such process are multi-effect desalination and multistage flashing while membrane process produces fresh water from the saline water using reverse osmosis (RO) principle at a high pressure [1]
At each pore entrance a liquidvapor interface is created due to the membrane hydrophobic nature that inhibits the liquid solution from penetrating into the pores [5].The ability of membrane to operate at lower operating temperatures (30-80 °C) is considered the main advantage of membrane technology than conventional distillation (˃100 °C) and lower operating pressures (˂100 kPa) than conventional membrane processes that are driven by pressure like in reverse osmosis (˃10 bar) [6]

Summary

Introduction

The supply and demand for sweet water were progressively increasing throughout the last two decades. Desalination of saline water is achieved by either membrane or thermal methods. Thermal process typically involves saline water boiling or evaporation collecting resultant distillate, examples of such process are multi-effect desalination and multistage flashing while membrane process produces fresh water from the saline water using reverse osmosis (RO) principle at a high pressure [1]. At each pore entrance a liquidvapor interface is created due to the membrane hydrophobic nature that inhibits the liquid solution from penetrating into the pores [5].The ability of membrane to operate at lower operating temperatures (30-80 °C) is considered the main advantage of membrane technology than conventional distillation (˃100 °C) and lower operating pressures (˂100 kPa) than conventional membrane processes that are driven by pressure like in reverse osmosis (˃10 bar) [6]. Membrane distillation has four principal configurations which are classified depending on the method used to withdrawn the vapor that

Methods

Results

Conclusion