Preface

Water and energy are closely interlinked and interdependent valuable resources that underpin economic growth and human prosperity. In every part of daily life, such as power generation, feedstock crop production, and fossil fuel processing, water is a ubiquitous source. Similarly, energy is vital for powering the water cycle, which includes collection, treatment, and distribution to end users. The mutual vulnerability of water and energy is amplifying due to rising demand because of exponential growth of gross domestic product (GDP), increasing population, and climate change.

Global water demand is projected to increase more than 55% by 2050 mainly due to a high GDP growth rate that will increase water demand for manufacturing, power generation, and domestic sector use by 400%, 140%, and 130%, respectively. This current demand trend will place 40% of the world's population at risk of water scarcity by 2050. Presently, more than 19,500 desalination plants in 150 countries produce roughly 38 billion m3 of water per year. This number is projected to increase to 54 billion m3 per year by 2030, which is 40% more compared to 2016. Desalination is the most energy-intensive water treatment process, consuming 75.2 TWh or about 0.4% of global electricity per year. **Figure 1** shows the desalination capacities of the world and Gulf Cooperation Council (GCC) countries and their share of different technologies.

**Figure 1.** *World desalination capacities [1].*

The conventional desalination technologies can be divided into two main categories: membrane separation (reverse osmosis [RO]) and thermally driven processes (multi-stage flash distillation [MSF], multi-effect distillation [MED], and adsorption desalination [AD]). In addition, forward osmosis (FO), capacitance deionization (CDI), membrane distillation (MD), and freezing and humidification dehumidification (HDH) are still in the research and development stages. Hybrid technologies such as MED–AD, MSF–MED, and RO–MSF have potential to overcome the limitations of conventional processes for greater recovery and performance. Unfortunately, conventional desalination processes are energy-intensive and non-eco-friendly. They only operate at 10–13% of their thermodynamic limit, which is not sustainable. To achieve UN sustainability goals, they should operate at more than 30% of the thermodynamic limit [2–6].

This book addresses key challenges related to the desalination industry. Energy recovery is an important parameter for efficient operation of a desalination plant. Chapter 1 provides details of energy recovery of membrane processes. Chapter 2 discusses membrane management. In an RO plant, the membrane is usually replaced every 3–5 years due to blockage and fouling. Membrane management is very important for reliable operation. Typically, recovery varies in the range of 40–45% of all desalination processes. Chapter 3 provides an outline for brine management to reduce marine pollution. Chapter 4 highlights water utilization in the agricultural sector. Typically, 70% of water is used for agriculture due to poor practices. This chapter presents best practices and efficient water utilization strategies. Chapter 5 provides an overview of the remineralization process after desalination. Remineralization is very important for achieving the World Health Organization's standards for drinking water quality. Chapter 6 discusses pre-treatment chemicals and how their injection can be optimized. Optimization of chemical injection in pre-treatment can lead to sustainable desalination and reduction of marine pollution.
