A Small RO and MCDI Coupled Seawater Desalination Plant and Its Performance Simulation Analysis and Optimization

Shouguang Yao,Mengting Ji

doi:10.3390/pr8080944

Abstract

To solve the problems of high specific energy consumption and excessive harmful ions in the water production of a small reverse osmosis (RO) plant, a desalination system coupling RO and membrane capacitive deionization (MCDI) is proposed in this study. Aiming at producing two cubic meters per day of fresh water with a salt concentration of less than 280 mg L−1, parameter matching optimization was carried out on two desalination system schemes of one-stage two-section RO and one-stage three-section RO coupled with MCDI. The results were compared with the parameter matching optimization results of the one-stage one-section RO and the one-stage two-section pure RO desalination system. The results show that compared with the pure RO desalination mode, the seawater desalination mode coupled with RO and MCDI reduces the specific energy consumption under the same effluent salt concentration. Moreover, it decreases the feed water pressure in front of the RO membrane, which can reduce the standard of high-pressure pump in a small seawater desalination plant. The energy consumption of the one-stage three-section RO and MCDI coupling system is lower than that of the one- stage two-section RO and MCDI coupling system, and the feed water pressure is also lower.

Highlights

Given the limited supply of fresh water on earth, seawater desalination is an effective way to produce this valuable resource
SW30-2540 Dow membrane andproduction takes the of 3 fresh water and a salt concentration of less than 280 mg L−1 is taken as the object of this study
This study proposes a seawater desalination system coupling reverse osmosis (RO) and membrane capacitive deionization (MCDI)

Summary

Introduction

Given the limited supply of fresh water on earth, seawater desalination is an effective way to produce this valuable resource. Reverse osmosis (RO) desalination has low energy consumption and compact structure, and the RO desalination process is used by approximately 80% of the total desalination plants worldwide [2]. One-stage RO desalination can achieve the salt concentration standard for direct drinking water, the produced water is acidic and retains excessive harmful elements, such as bromine ion [3]. If a two-stage RO system is adopted, only part of the water quality problems can be solved, and the energy consumption and cost will greatly increase. To increase the water recovery of the system and reduce the specific energy consumption, it needs larger feed water pressure, which greatly improves the high-pressure pump standard, but it needs to maintain the specific energy consumption as high as 10–20 kWh m−3 [4] without an energy recovery device.

Methods

Results

Conclusion