Preface

The Sustainable Development Goals (SDGs) set to achieve by 2030 have been adopted by United Nations with the consent of membrane states has brought back water‐related issues to forefront. Water quality and sanitation (Goal 6) has been one of the main focus under SDGs, which is closely intertwined with other goals such as poverty; health; sustainable cities and communities; responsible consumption and production, heath, poverty reduction, and ecosystems and sustainable consumption and production; life below water, and life on land (Goals 1, 3, 11, 12, 14, and 15). These goals recognize a vial links between water resources, accessibility, quality, and key socioeconomic factors associated with sustainable environmental and development.

On the other hand, increasing industrial manufacturing pursuits, economical activities, rapid urbanization and depleting freshwater sources due to which world is concerned on impending water scarcity. In the last two decades, freshwater consumption on a global scale has doubled that of population growth. This drastic water consumption pattern have reached across communities, societies, and larger geographical locations. This extended water consumption not restricted to limited sectors or region are unsustainable. Thus, the drastic increase in water consumption has disrupted the traditional water demand and supply patterns thereby arise of uncertain future. However, immediate measures may intervene in the escalating situation and may change for good in a long run. Nevertheless, as of today, water consumption is increasing and demand for freshwater driven in population growth and urbanization where the higher per capita water consumption in growing, domestic, and industrial and/or socio‐economic activities across the sectors.

In addition to this, poor water resource management policies, governance and inefficient implementation/development practices, unorganized as well as unscientific agriculture activities, and lack of water recycling efforts are also likely to diminish both quality and quantity of water supplies across the globe. While industries continue to produce and discharge wastewater as well as ground water level expected to deplete, which leads developing countries to experience more acute and pervasive water insecurity. It is also expected that some developed countries will also face strains on their water resources and supply chain. If this continues, regions and countries with poor water resource management policies are unlikely to prepare for future situation in which addressing water‐related challenges might face collective challenges, including poor economic growth, growing inequality, less economical activities, poverty, deteriorating health and sensitization infrastructure, greater risk of disease, and risk of internal political instability.

World witnesses addition of 2–2.5 billion people to current population count by 2050. This will add up to the stress on food production, power generation, and water supplies. The efficient management of these interconnected nexus between water, energy, and food mainly depends on the water managers. Per capita water consumption across the globe considerably varies, in developed regions it is estimated to an average value of ~200 L per person per day. However, on an average, water requirement for human basic needs is estimated ~50 L per person per day at a global level. However, there has been a substantial reduction in water consumption recorded due to promising innovations and technologies adopted in developed countries in sectors like agriculture, domestic usage, municipal consumption, power generation, and so on. However, at larger global level, present water usage patterns do not reflect the sustainability in the face of increasing population growth and climate change scares.

On the other hand, by now, major freshwater source of water has been exploited and water that has been consumed is laying in the form of wastewater in treatment plants, discharge ponds, disposal zones, or in the open environment. Even though there have been efforts to recycle reusable quality of water, however, efforts are limited. It is estimated that at global level, an average of ~15% of wastewater is being recycled immediately after their utilization. At the same time, advanced techniques are being rapidly developed to improve water security through establishing long‐term infrastructure construction for both desalination and/or wastewater treatment targeting various sectors and capacities. These efforts are also being made to minimize the energy consumption and impact on environments. Therefore, shifts have been made toward design and development of energy efficient, economical, high‐performing desalination, and wastewater treatment technologies using cleaner energy such as solar‐assisted, biofuels, wind, and nuclear energy that can significantly address increasing demand for portable water and generation of reusable quality freshwater from wastewater sources. Therefore, seawater desalination and water recycling from waste sources are increasingly becoming major issues for water managers and priority policy issue for governments at the international level.

In addition to this, today world is better positioned to address emerging crisis than ever. Today we have vast information, the knowledge, innovation that is taking place, the technologies that are being developed, and the economic prosperity that can be a vital resources to create infrastructure to manage existing water resources as well as impending water crisis much more efficiently and effectively than ever. The enormous scientific research undertaken across the sectors at global level ensuring systematic understanding of water crisis and measures suitable to address them which is continuously adding to our information/knowledge, new findings, and tools.

In this context, present book provides detailed account of various policies, guidelines and norms framed for water management and usage from various agencies and government across the world. Sections of the chapters also discuss in detail the recent advances that are taking place at global level to design, develop, and implement the global water resource monitoring information system to obtain and distribute the information needed for efficient water management. Also, various regulatory norms followed for various contaminants and their presence in various sources have been discussed in detail to provide a wider spectrum of information. These sections include the specific norms and guidelines for dangerous conventional as well as emerging pollutants that potentially cause serious threat to treatment techniques. For this purpose, various reports, public documents, publications, case studies, monitoring data, and national and international guideline documents on both water quality and treatment guidelines using appropriate technologies have been discussed. On the technologies front, timely, comprehensive, and forward‐looking detailed information on various advanced technologies that involve for desalination are mainly phase change technologies including thermal desalination (humidification/dehumidification, solar chimney, multistate flash distillation, multi‐effect distillation, vapor compressed distillation, electrodialysis, reverse osmosis, nanofiltration, forward osmosis, electrodialysis, electrodialysis reversal and electro‐osmosis, functional polymers, magnetic materials, and various functional nanomaterials, whereas wastewater treatment processes involve physical treatment techniques (screening, grit separation, floatation, filtration, and so on), chemical treatment methods (advanced oxidation/reduction, ion‐exchange, photocatalysis), and biological treatment technique (aerobic and anaerobic, biological filtration) processes, physico‐chemical techniques like granular‐activated carbon (GAC) adsorption and absorption, advanced membrane‐based separation processes like forward osmosis, capacitive deionization, advanced ion‐exchange methods precipitation, coagulation, flocculation, multi‐flash distillation processes, and so on, which have been discussed in detail.

Nonetheless, even in the presence of advanced technologies, water resources will continue to experience newer challenges which will directly affect the environmental sustainability at large. These challenges include (i) increasing water scarcity, (ii) vulnerability to pollution and contamination, (iii) degrading ecosystem, (iv) deforestation, (v) continuing urbanization, (vi) excessive use of agricultural chemicals, (vii) disturbance to biodiversity, (viii) intense droughts and shifts in precipitation patterns, (ix) rising sea levels, (x) looming climate change impacts, etc. Nevertheless, collective efforts and innovative strategies can provide futuristic solution to achieve water and environmental sustainability. Some of these may include (i) integrated water resource management, (ii) watershed management, (iii) conservation and restoration of ecosystems, (iv) adaptation to climate change (v) sustainable agriculture, (vi) promotion of green infrastructure, (vii) educational outreach, and so on. This book is a small contribution toward understanding some of the aspects made in the field of water treatment and wastewater recycling mentioned here. In addition to giving detailed accounts of recent advances in materials development and process designs aiming water treatment and wastewater treatment, this book hope to raise awareness among young and next generation regarding the crucial aspects of conserving natural water resources, safeguarding groundwater, minimizing water consumption, recycling used water, discharge of...