Integrated water, energy and resources production for sustainable seawater desalination

Introduction

LIFE INDESAL tackles the challenge of supplying safe freshwater from alternative resources in a reliable way, within the paradigm of circular economy and climate change. For this purpose, it aims at developing and demonstrating a novel integrated and circular seawater desalination process, producing multi-purpose desalinated water, renewable energy, and resources simultaneously, with a low carbon footprint.

Integrated Process Overview

The integrated process consists of a high energy efficient RO system (based on low pressure multistage systems, LMS), which produces high quality water.

Brine Treatment

The generated brines, instead of being disposed of, are treated by Reverse Electrodialysis (RED), capable of obtaining energy from the salinity gradient of the LMS RO brines. The concentrated stream is further treated by electrodialysis with bipolar membranes (EDBM), generating NaOH and HCl for the desalination process itself, making the plant self-sufficient.

Recirculation

The diluted RED effluent is recirculated upstream of the RO, decreasing the intaken seawater salinity.

Energy Savings and Environmental Impact

The targeted energy saving linked to LMS RO is 0.2 kWh/m³ and the renewable energy produced by RED is up to 0.1 kWh/m³, leading to:

1. A 7% reduction in energy consumption over a conventional RO desalination system.
2. A 3.5% reduction in energy consumption over a conventional RO desalination system.

Considering a 450,000 m³/d SWRO plant, the LIFE INDESAL configuration would alleviate:

• 33 GWh/yr and 16 GWh/yr, which is equivalent to:
  • 8,377 ton CO2/yr
  • 4,131 ton CO2/yr, respectively.

This clearly offers great potential.

Project Ambition and Impact

The ambition and demonstrative character of the project (2-year testing at prototype scale in real conditions) together with its highly sustainable holistic approach, its transferability, and its complementarity with other R&D initiatives supported by significant dissemination efforts will boost the implementation of LIFE INDESAL solutions in new/refurbished full-scale plants.

Multiplying Effects

This will further multiply its technical, socio-economic, and environmental impact. Moreover, its modularity and transferability to other industrial areas will catalyze its effects.