Advanced Water Technologies

Concepts and Applications

P.K. Tewari

• Publisher: CRC Press
• Year: 2020
• ISBN:
  9781351589284
• Edition: 1
• Topic: Ciencias físicas
• Subtopic: Química industrial y técnica

The book explores basic concepts and advanced topics in the field of water technologies. It deals extensively with advances in materials, material selection, preparation, characterization and application. The relevance of water technologies in industries is considered, and a section is dedicated to describing and analyzing the technologies required for water reuse and advanced purification, including desalination. Nuclear desalination, low-carbon desalination and water purification technologies to address the adverse impacts of climate change are examined from both the adaptation and mitigation points of view.

Aimed at senior undergraduate/graduate students in chemical, civil and environmental engineering, along with wastewater and desalination researchers, this book:

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• Details advanced water treatments for varied processes.

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• Describes membrane and desalination techniques for water reuse and advanced purification.

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• Elaborates water technologies at both the front and back ends of the process.

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• Discusses modern technologies for effluent treatment and water recycling.

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• Explores the role of information technology in the water sector.

1Water

1.1WATER—A MIRACLE COMPOUND

Water is a miracle liquid. The Earth is unique among the known celestial bodies in having three-quarters of its surface covered by water. Life has evolved in water. The regeneration and redistribution of water through evaporation and condensation is a continuous process, making it seem endlessly renewable. Water is not a commodity. It is life-making material. Whenever we look for a life, we look for a drop of water first.

The association of human beings with water starts even before birth—the fetus swims in it for nine prenatal months within the warmth of the mother’s womb. The very life on this planet begins within water. Every cell within the organic structure of the human body has a fluid interior, e.g., blood is 90% water, kidneys are 82% water, muscles are 75% water, the liver is 69% water and living bones are 22% water. A living person is 70% water by weight. On average, a person drinks about five times their own weight of water in a year. In a normal life span, a person consumes about 30,000 L of water. Most of the water in the organic structure in the human body is contained within our cells. The body of a newborn consists of more water (about 75%) than that of an elderly person (50%). A muscular body contains more water than a fat body, as body fat contains less water.^{1, 2} Human beings can live without food for several months, but without water for only a few days. Table 1.1 gives the tentative water balance in a human body.

TABLE 1.1
Water Balance in a Human Body

Water Intake	Milliliters	Water Out	Milliliters
Liquid drinks	900	Urine	1000
Food	800	Stool	100
Oxidation of food	300	Sweat/lungs	900
Total	2000	Total	2000

Can we think of a human life without water? Many of us will say no, it’s not possible, while a few of us will say yes, but only for a few hours. Both are right. Human beings cannot live long without water. Dehydration (lack of water) kills us faster than starvation (lack of food). A person suffering from dehydration with just a small water loss may display symptoms including irritability, fatigue, nervousness, dizziness, weakness and headaches. The food we eat requires water for cultivation and processing. We use water for entertainment and for sports such as swimming, sailing and rowing. When water becomes ice, we ski or ice skate. Water is required for cooking, washing, bathing, cleaning and recreational activities. Historically, civilizations blossomed around rivers. Equally, those same civilizations were wiped out as sources of fresh water dried up.

Water is the only chemical substance on earth that exists naturally in all three states. It normally exists in its liquid state and does not have smell or taste. It freezes at 0°C and boils at 100°C. Water is an essential life support system for most living beings and the most widely used of all solvents. It is a universal solvent. Its chemical formula is H₂O, meaning that a water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds.

In addition to the standard atoms of hydrogen (H, mass 1) and oxygen (O, mass 16), water contains a very tiny fraction of heavier atoms of hydrogen (deuterium H₂ and tritium H₃) and oxygen (O₁₈), called isotopes. Surface water on earth follows the water cycle, also called the hydrological cycle. Surface water resources (oceans, rivers, lakes, etc.) undergo evaporation, the water vapors thus formed condense as rain (precipitation), the rain waters run to the rivers/oceans as well as to the interior of the Earth, and the cycle is repeated. The larger fraction of the lighter atom evaporates relatively faster than the tiny heavier atom, while in the precipitation stage the heavier fraction comes down first. This subtle phenomenon results in minute differences in the ratio of the heavy to the light atoms of H and O in water in different parts of the water cycle, as well as in the resultant water and its ultimate storage location. In other words, every drop of water carries its own isotopic fingerprints. The minute differences in the isotopic ratio were traditionally measured using mass spectrometers, and useful information on the origin, pathway and age of the water samples was derived. In recent years laser spectroscopy has begun to be used. Such procedures, called isotopic techniques, form the basis of the science called isotope hydrology.

The specific heat of water is 4.2 J/g°C, which is higher than that of any other common substance. Specific heat is a measure of heat to be added to or released from a substance to change its temperature. This means that 4200 J of heat when added to 1.0 kg of water increases the temperature of water by 1°C. This is a significant amount of heat required to make a small change in the temperature of water. It takes a lot of heat to heat up the water, but once it is hot, it remains hot for a long time. Solids tend to have a lower specific heat capacity. Think of stirring hot soup with a metal spoon. Metal spoons heat up fast. This is because metal has a very low specific heat capacity, so a small amount of heat makes a large temperature change, and water has a high specific heat capacity. Water plays a very important role in temperature regulation, e.g., sweating to dissipate the heat from the human body and control body temperature.

Latent heat of vaporization is another unique property of water useful for several purposes. It is the heat required to convert water into steam at constant temperature. Water molecules form hydrogen bonds with one another. The partial negative charge on the oxygen (O) of one molecule can form a hydrogen bond with the partial positive charge on the hydrogen of other molecules. Water molecules are drawn to other polar ions. Because the bonding electrons are shared ...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• Preface
• About the Author
• Chapter 1: Water
• Chapter 2: Membrane Technologies for Water Purification
• Chapter 3: Nanotechnology for Water Purification
• Chapter 4: Nanocomposite Membranes in Water Treatment
• Chapter 5: Desalination
• Chapter 6: Water Treatment and Purification
• Chapter 7: Wastewater Treatment, Recycling and Reuse
• Chapter 8: Guidelines for Setting up Advanced Water Technology Plant
• Chapter 9: Challenges and Opportunities
• Chapter 10: Artificial Intelligence and the Internet of Things in Water Management
• Index