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Techno-economical assessment of defluoridation of water


Abstract and Figures

Fluoride while beneficial for human health at low concentration shows harmful impacts on skeletal fragility, kidney, nerve damage, etc., if consumed in excess. Several techniques were applied for the removal of excess fluoride from water such as adsorption, membrane separation, ion exchange, precipitation, etc. The selection of a particular technique depends on its specific advantages and disadvantages. These techniques were initially developed at a lab scale and further evolved as pilot plants. Successful pilot plant studies were subsequently developed into community-based applications for fluoride removal. Some of these processes not only removed fluoride but also other unwanted species, namely, phosphate, arsenic, bicarbonates. These plants are extremely popular in various Asian and African countries as they are useful for providing safe drinking water to underprivileged people. In such studies, adsorption was one of the popular methods that employed various adsorbents and the overall cost was about 20 USD/m³. Similarly, precipitation methods like Nalgonda technique were also successfully applied at the cost around 15 USD/m³. Electrocoagulation using aluminium electrode is also a popular method having an operational cost of about 1 USD/m³, whereas equipment cost is substantially high. On the other hand, membrane separation has the highest installation cost of about 800k USD and operational cost of about 0.2 USD/m³. This chapter is specifically discussing about the economics, cost analysis of water defluoridation, and possible applicability.
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Edited by
Mohammad Hadi Dehghani
Tehran University of Medical Sciences (TUMS), School of Public Health,
Department of Environmental Health Engineering;
Institute for Environmental Research,Center for Solid Waste Research,
Tehran University of Medical Sciences, Tehran, Iran
Rama Rao Karri
Petroleum and Chemical Engineering, Faculty of Engineering,
Universiti Teknologi Brunei, Brunei
Éder Cláudio Lima
Institute of Chemistry-Federal University of Rio Grande do Sul (UFRGS),
Porto Alegre, RS, Brazil
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In the Name of God, the Most Gracious, the Most Merciful
I am thankful to God Almighty that I succeeded in writing this book with the
help of my colleagues.
I dedicate this book to my parents, my brothers and my sister who are always
praying for me.
I especially appreciate my lovely wife and my children (Amir Parsa & Yasamin)
who contributed to my progress and success with their patience and forbearance.
Prof. Dr. Mohammad Hadi Dehghani
I dedicate this book to the memory of my Father Karri Sri Ramulu
I also dedicate this to my mother Karri Kannathalli, who protected, guided
and supported me in all these years. She was my inspiration for driving me to
achieve the best. She was my superwoman and constant inspiration.
I also thank my lovely wife, Soni, my cute children Yajna & Jay, without their
support and understanding, this book as well as my research achievements
were not possible.
I also dedicate this book to my mentor Dr. Ch. Venkateswarlu, who inspires
me to take new challenges.
Dr. Rama Rao Karri
I dedicate this book to my wife, Cristiane G. Roman, for her tireless support
and for one that has believed in me in my initial career.
Prof. Eder C. Lima
Contributors ix
Foreword xi
1. Effects on Human Health due to
Anuradha Singh, Jagvir Singh
1.1 Introduction 1
1.2 Sources of fluoride 2
1.3 Chemistry of fluoride 4
1.4 Beneficial impacts 4
1.5 Health effects of fluoride 5
1.6 Escape methods 10
1.7 Conclusion 10
Acknowledgment 11
References 11
2. An overview of conventional
and advanced water
defluoridation techniques
Saif Ullah Khan, Vinay Pratap, Mohammad
Kashif Uddin, Izharul Haq Farooqi
2.1 Introduction 17
2.2 Conventional methods 18
2.3 Chemical precipitation 18
2.4 Ion exchange 20
2.5 Membrane filtration 21
2.6 Adsorption 25
2.7 Electrocoagulation 30
2.8 Conclusion and future perspectives 34
References 34
3. Adsorption: Fundamental aspects and
applications of adsorption for effluent
Éder Cláudio Lima, Mohammad Hadi Dehghani,
Ashish Guleria, Farooq Sher, Rama Rao Karri,
Guilherme L. Dotto, Hai Nguyen Tran
3.1 Fundamentals of adsorption 41
3.2 Isotherms of adsorption 43
3.3 Thermodynamics of adsorption 57
3.4 Kinetic of adsorption 67
3.5 Conclusion 84
References 84
4. Adsorbents for removal of fluoride
from water
Krishna Yadav, Sheeja Jagadevan
4.1 Introduction 89
4.2 Synthesis and types of adsorbent for fluoride
removal 90
4.3 Bio-sorbents 103
4.4 Nanoparticles- and nanocomposites-based
adsorbents 106
4.5 Desorption/regeneration of adsorbents and their
performance 108
4.6 Fluoride adsorption mechanisms 111
4.7 Conclusion 111
Challenges and prospects 111
References 112
5. Entropy and MTOPSIS assisted central
composite design for preparing activated
carbon toward adsorptive defluoridation
of wastewater
Kumar Anupam, Virender Yadav, Rama Rao Karri
5.1 Introduction 119
5.2 Research methodology 121
5.3 Results and discussion 128
5.4 Conclusion 138
References 139
6. Sustainable green approaches in
sorption-based defluoridation: Recent
Richelle M. Rego, Mahaveer D. Kurkuri,
Madhuprasad Kigga
viii Contents
6.1 Introduction 141
6.2 Natural materials 146
6.3 Biomaterials as sorbents for
defluoridation 151
6.4 Carbonaceous materials from wastes 156
6.5 Agro-industrial waste-based sorbents 160
6.6 Conclusions and future perspectives 165
Acknowledgments 165
Conflict of interests 165
References 166
7. Techno-economical assessment of
defluoridation of water
Saurabh Joshi, Somen Jana
7.1 Introduction 175
7.2 Adsorption 176
7.3 Precipitation-coagulation 180
7.4 Electrocoagulation 182
7.5 Ion-exchange resin 183
7.6 Membrane-based methods 186
7.7 Conclusion 191
References 191
8. Global water challenge and future
Usha Kumari, Kurella Swamy, Ajita Gupta, Rama
Rao Karri, Bhim Charan Meikap
8.1 Introduction 197
8.2 Various sources of fluoride in groundwater and
their circulation 199
8.3 Water scarcity 199
8.4 Social and political involvement in avoiding
water scarcity 201
8.5 Requisite management 202
8.6 Strategies after treatment of wastewater 203
8.7 Persisting water challenge 204
8.8 Various opportunities to handle
wastewater 206
8.9 Future perspective 206
8.10 Conclusions 208
References 208
Index 213
Kumar Anupam Chemical Recovery and Bio-
renery Division, Central Pulp and Paper Re-
search Institute, Saharanpur, India
Anuradha Singh Department of Zoology, Ra-
ghuveer Singh Government Degree College,
Lalitpur, India
Mohammad Hadi Dehghani Department of
Environmental Health Engineering, School of
Public Health, Tehran University of Medical Sci-
ences, Tehran, Iran; Institute for Environmental
Research, Center for Solid Waste Research, Teh-
ran University of Medical Sciences, Tehran, Iran
Guilherme L. Dotto Chemical Engineering De-
partment, Federal University of Santa Maria–
UFSM, Santa Maria, Brazil
Izharul Haq Farooqi Department of Civil Engi-
neering, Zakir Husain College of Engineering &
Technology, Aligarh Muslim University, Aligarh,
Ashish Guleria Department of Applied Scienc-
es, WIT Dehradun, Dehradun, India
Ajita Gupta Department of Chemical Engi-
neering, Indian Institute of Technology (IIT)
Kharagpur, West Bengal, India
Sheeja Jagadevan Department of Environmental
Science and Engineering, Indian Institute of Tech-
nology (Indian School of Mines), Dhanbad, India
Somen Jana Department of Chemical Engineer-
ing, Banasthali Vidyapith, Banasthali, India
Saurabh Joshi Department of Chemical Engi-
neering, Banasthali Vidyapith, Banasthali, India
Rama Rao Karri Petroleum and Chemical En-
gineering, Faculty of Engineering, Universiti
Teknologi, Gadong, Brunei Darussalam
Saif Ullah Khan Department of Civil Engineer-
ing, Zakir Husain College of Engineering & Tech-
nology, Aligarh Muslim University, Aligarh, India
Madhuprasad Kigga Centre for Nano and Ma-
terial Sciences, JAIN (Deemed-to-be-Universi-
ty), Jain Global Campus, Bengaluru, India
Usha Kumari Department of Chemical Engi-
neering, Indian Institute of Technology (IIT)
Kharagpur, West Bengal, India
Mahaveer D. Kurkuri Centre for Nano and Mate-
rial Sciences, JAIN (Deemed-to-be-University),
Jain Global Campus, Bengaluru, India
Éder Cláudio Lima Institute of Chemistry, Fed-
eral University of Rio Grande do Sul, Porto-
Alegre, Brazil
Bhim Charan Meikap Department of Chemi-
cal Engineering, Indian Institute of Technol-
ogy (IIT) Kharagpur, West Bengal, India; De-
partment of Chemical Engineering, School of
Chemical Engineering, Howard College Cam-
pus, University of Kwazulu-Natal (UKZN),
Durban, South Africa
Vinay Pratap CSIR-National Environmental
Engineering and Research Institute (CSIR-
NEERI), Nagpur, India; Academy of Scientic
and Innovative Research (AcSIR), Human Re-
source Development Centre, (CSIR-HRDC)
Campus, Ghaziabad, India
Richelle M. Rego Centre for Nano and Material
Sciences, JAIN (Deemed-to-be-University), Jain
Global Campus, Bengaluru, India
Farooq Sher School of Mechanical, Aerospace
and Automotive Engineering, Faculty of Engi-
neering, Environment and Computing, Coven-
try University, Coventry, United Kingdom
Jagvir Singh Department of Chemistry, ARSD
College (University of Delhi), New Delhi,
Kurella Swamy Department of Chemical Engi-
neering, National Institute of Technology (NIT)
Srinagar, Jammu and Kashmir, India
Hai Nguyen Tran Institute of Fundamental and
Applied Sciences, Duy Tan University, Ho Chi
Minh city, Vietnam; Faculty of Environmental
and Chemical Engineering, Duy Tan Univer-
sity, Da Nang, Vietnam
x Contributors
Mohammad Kashif Uddin Department of
Chemistry, College of Science, Majmaah Uni-
versity, Zul campus, Al-Zul, Saudi Arabia
Krishna Yadav Department of Environmental
Science and Engineering, Indian Institute of
Technology (Indian School of Mines), Dhan-
bad, India
Virender Yadav Department of Chemical Engi-
neering, Maharishi Kashyap Government Poly-
technic, Panipat, India
Increasing water pollution caused by the
activities of urban and industrial communi-
ties has severely affected the quality of
water resources. One of the critical factors in
determining the quality of drinking water is
uoride concentration. Fluoride is one of the
common elements in water that enters
through various natural ways and human
activities. Therefore, the importance of uo-
ride removal from water sources is very
important. Given the adverse effects arising
from excess uoride in water, appropriate
methods should be employed to eliminate
it. There are various techniques for getting
rid of excess uoride from water. This book
focusses on the occurrence and fate of uo-
ride, its environmental and health impacts,
the application of green technologies for the
removal of uoride from water using
adsorption processes, nano-adsorbents, con-
ventional and advanced technologies.
This book will be very useful for the MS and
PhD students who are working in environ-
mental sciences and water and wastewater
treatment elds, water scientists, researchers
who are working on advanced technologies for
environmental remediation, policy makers,
and managers who work on water purication
and environmental nanotechnology.
Alireza Mesdaghinia
Emeritus Professor of Environmental Health,
Tehran University of Medical Sciences, Iran.
President, Iranian
Association of Environmental Health
Green Technologies for the Defluoridation of Water.
DOI: 10.1016/C2020-0-02666-6 1 Copyright © 2021 Elsevier Inc. All rights reserved.
Effects on Human Health due to Fluoride
Anuradha Singha, Jagvir Singhb
aDepartment of Zoology, Raghuveer Singh Government Degree College, Lalitpur, India,
bDepartment of Chemistry, ARSD College (University of Delhi), New Delhi, India
1.1 Introduction
Fluorosis is the curse of modern society (especially rural society) that is being spread like a
Sursa and thousands of people are feeling the same as someone who falls under the python.
Fluorosis occurs when a person continues to practice soluble uoride-rich drinking water
more than the standard limit (Mohanty and Rao, 2010; Gao etal., 2014; Mahmoud etal., 2020;
Dehghani etal., 2020; Dehghani etal., 2021). In addition to drinking water, uoride enters
the human body mainly through food, air, medicines, and cosmetics (Hedman etal., 2006),
Peckham et al. 2014) but about 60% enter the body only through drinking water. It has been
observed that uoride enters the human body through tea, uoride-containing toothpaste,
and highly soluble uoride-containing drinking water. Fluoride also reaches our body
through cold drinks (Balzar Ekenback etal., 2001). It becomes even more difcult to estimate
his mental instincts. When the amount of uoride in ordinary drinking water is high, uoride
in the human body accumulates itself by removing hydroxide from the bones and gives rise
to bone uorosis (Marthaler and Petersen, 2005; Moss and Kumar 2021) and (Gao etal., 2014;
Amini etal., 2016; Dehghani etal., 2019).
Till now, it was believed that uorosis was more common in physically developed youth
and adults but it has been observed that it is more fatal in children up to the age of 12 years.
The children of this age group are growing and at this age, their body tissues are also soft so
that uorosis soon invades and inltrates the body (Thompson, 2018; Dehghani etal., 2018).
If the mother of the fetus consumes water containing uoride, it is very harmful to the baby
growing in the womb. Children usually become crippled and diseased by the age of 2–3.
Initially, the leg bone becomes square and at and later the child remains helpless. It has been
observed that uorosis disease develops very quickly in uneducated, poor, and malnourished
villagers (Buzalaf and Whitford, 2011; Anbazhagan etal., 2019; Dehghani etal., 2016; Youse,
Ghalehaskar et al., 2019). In the grip of uorosis, a man starts to grow untimely, his waist starts
tilting and he becomes helpless by walking (Fawell etal., 2006; Yadav etal., 2019). Sometimes
2 1. Effects on Human Health due to Fluoride
Green technologies for the deuoridation of water
he also falls prey to dumbness. All these are some such social tragedies that are very important
to discuss in today’s context (Dean, 2015; Yeung etal., 2005; Petersen and Lennon, 2004).
Everyone knows how annoying a disabled person’s life is. Physical disability is a curse
that affects not only the person but also his entire family. In such a situation, when all the
people of a family settling in the village become victims of collective disability, then the plight
of that village will be unthinkable (Dunipace etal., 2006; Dawes, 2003) but when he learns
that this disability called uorosis is acquired by treating him as a drinking water for living
water in which uoride is more soluble than the standard limit.
Young men and women also begin to experience old age by the time they reach the age
of 35–40 years (National Research Council, 2006). His waist starts bowing and physical
strength starts to decline. The arms and legs become deformed, the teeth begin to turn yellow
and the gums begin to thaw. Many daughters who have been married to any other village
also cannot remain untouched by the ill effects of this disease in the uorosis-affected village
(Cagetti etal., 2013). The ill-effects of disability start appearing more on women after becom-
ing mothers. A person affected by uorosis is not able to participate in social activities in a
big way because frustration is awakened in him and he becomes infatuated with an inferior-
ity complex (Wong etal., 2010).
Fluoride is a neurotoxin, meaning it is dangerous for our physical and mental develop-
ment. Neurodevelopmental cases affecting children all over the world, such as autism, atten-
tion decit disorder, and other malformations are due to the use of uoride and other similar
industrial side products and the relationship between them is now clear. Its effects on health
have caused serious concerns to mankind, including fatal diseases such as problems with
bones, teeth, cancer, reproductive, gastrointestinal, endocrinological, and neurological devel-
opment. This uoride is also the cause of intestinal ulcers, impotence in men, and infertility
in women due to repeated miscarriages.
A person affected by uorosis gets old in his youth and is helpless to do anything. He
becomes so weak that he cannot walk or carry weight easily. By reaching the climax of uorosis,
he becomes fascinated by the hands of others even for eating. The hair turning white and looking
physically deformed in youth is a common sight in the uorosis-affected area, when a man
becomes helpless due to disability, there is no other way for him than to stick with sticks. Being
physically helpless, he cannot even work as a labor and has no choice but to beg. Being an
agricultural country and in the tropics, agricultural laborers in India must work hard most of
the day and drink more water (Sarkar and Pal, 2014). Because their income is also low, they
cannot even imagine nutritious food. For all these reasons, the body’s resistance to power
decreases when drinking uoride-containing water continuously (Basha etal., 2011; Petersen
and Lennon, 2004). This can be directly related to their illiteracy. The presented chapter gives a
detailed description of the effect of the increasing limit of uoride on human health and life.
1.2 Sources of fluoride
Fluoride is the thirteenth (13th) element found in abundance in the terrain. It was designed
in 1886 by Professor Henry Mison. On the Earth planet, uoride elements are found naturally
in soil, water, and food items. It is also being mass-produced articially for use in every-
day household items such as toothpaste, mouthwash, and various chemical products
1.2 Sources of fluoride 3
Green technologies for the deuoridation of water
(Zuo etal., 2018). Fluoride has long been used as rodents and pesticides to kill mice and pests
which is a very acute poisoning that is more toxic than lead and less toxic than arsenic. The
increasing use of uoride crosses its safe limit in drinking water, which has taken a terrible form.
Fluoridation of water has been banned in many important countries such as France, Germany,
Austria, Belgium, Denmark, and Greece. In some other countries, such as Switzerland, UK,
Norway, and Spain, uoride is now zeroing in almost 90% of the water supplied to households.
Fluoride enters the body by various sources which are described as follows.
1.2.1 Water and food
Fluoride mixed salts are abundant, so the presence of uoride is found in water, foods, and
crops. Fluoride in drinking water poses health problems when intake exceeds mg per liter,
that is, the human body has the ability to tolerate uoride content to a limit. The Bureau
of Indian Standards and the World Health Organization set a maximum uoride limit of
1.5 ppm (Li, 2003) (Table 1.1).
The amount of uoride in foods depends mainly on soil type, salts present in the soil,
and available water. High uoride-rich water increases the amount of uoride in food and
vegetables (Ortiz-PD etal., 2003).
TABLE 1.1 Fluoride concentrations for different types of food (Malde 1997; Li, 2003).
Food items Quantity of uoride available (mg/kg)
Wheat 4.6
Peppermint 4
Garlic 5.0
Rice 5.9
Potato 2.8
Ginger 2.0
Gram 2.5
Carrot 4.1
Turmeric 3.3
Soybean 4.0
Banana 2.9
Mutton 3–3.5
Cabbage 3.3
Mango 3.2
Beef 4-5
Tomato 3.4
Apple 5.7
Pork 3–5
Cucumber 4.1
Guava 5.1
Fish 1–6.5
Ladynger 4.0
Tea 60–112
Coconut water 0.32–0.6
Spinach greens 20
Coriander 2.3
Eggplant 1.2
Sea food 326.0
4 1. Effects on Human Health due to Fluoride
Green technologies for the deuoridation of water
1.2.2 The medicines
Sodium uoride is benecial in osteosclerosis and diseases, such as osteoporosis and dental
care. Fluorosis and uoride-related diseases are caused by frequent and prolonged use of
uoride (Alkurdi etal., 2019).
1.2.3 Toothpaste and mouthwash
It is well known that most toothpastes contain uoride. Mouthwash is also a type of uoride-
containing water that absorbs uoride in the bloodstream within minutes. Keeping in mind
the side effects of uoride, two conditions were placed under the Drug and Cosmetic Act
1945 (Table 1.2).
1.3 Chemistry of fluoride
Fluoride (F) is the simplest monoatomic anion which has a chemical formula F and behaves
like a base. It is count in trace elements and found as trace quantity in water, beside this,
uoride also found in various minerals. The oxidation state of uoride is one so found due
to this it is very reactive and always found in nature as a combination state (Skorka-Majewicz
etal., 2020).
1.4 Beneficial impacts
Not only is calcium capable of improving the bone structure and strengthening teeth, but it
also has an important role in uorine which in association with sodium is widely used in
medicine and industry (Dey and Giri, 2016).
Role of sodium uoride in human life:
1. Stimulates the formation of bone cells—osteoblasts, strengthens the skeleton.
2. The tooth participates in the formation of enamel. The structure of toothpaste has a
bactericidal effect on bacteria, improving blood circulation in the gums.
3. At optimum concentrations, sodium uoride for children is the prevention of caries and
the development of periodontal disease (damage to the tissues of the teeth).
4. It is used as a detergent, sodium uoride is used in the chemical industry (metals for
cleaning and melting metals, in welding) and for the production of freon.
TABLE 1.2 Recommendation data use of fluoride toothpaste for children (Skorka-Majewicz et al., 2020).
Age F- concentration Daily amount taken
6 months to 1 year 0.1 mg/d Like smear
1–2 years 0.25 mg/d Pea sized
2–6 years 0.5 mg/d Pea sized
6 year 1.0 mg/d 1 cm
No toothpaste should contain more than 1000 ppm of uoride. The manufacture and expiration date should be clearly
written on each toothpaste (Jiang etal., 2005).
1.5 Health effects of fluoride 5
Green technologies for the deuoridation of water
1.5 Health effects of fluoride
Fluoride is a type of double-edged sword, that is, the amount of uoride in the body is as
harmful as the large amount. Fluorine is a very important element for the human body
because with the help of uorine the normal saliva of bones and enamel of teeth are formed
(Srivastav and Kaur, 2020). The human body contains about 96% of the total uoride and is
mostly found in bones and teeth. Some elements micro to minimum amounts are very impor-
tant to keep the health within the standard range. But their quantity beyond the standard
limit causes adverse effects on health and serious diseases are born. Fluoride also falls in this
category, which is available everywhere in the world (Stephen KW et al., 1994; Trivedi N et
al., 1993). The microscopic amount of uoride in drinking water (within the standard range)
is essential for the safety of the enamel of the teeth, while if its soluble quantity exceeds the
standard limit, the human suffers from severe illness. After uorosis is found, it is found that
there is no cure and as a result, dental uorosis, deformity of bones. and serious illnesses
related to muscles and muscles go home forever (Hjortsjö etal., 2014; Qin etal., 2006).
1.5.1 Effect of minimal fluoride in the body
The presence of uoride in the anatomy of humans is extremely important. Some enzyme
processes are either slowed or accelerated by low amounts of uoride and chemical processes
are performed with other organic and inorganic elements. The highest amount of calcium is
found in bones and teeth in the body (about 110 ppm uoride is found in the normal tooth
enamel). Calcium is an electrically positive element and by its positive effect, the maximum
amount of electrically negative uoride is found (Chinoy NJ et al., 1992). Thus, uoride
accumulates in the form of “calcium uoapatite crystals.” The deposition of this crystal is
the root cause of the disease called uorescein in the human body. Proteins, enzymes, and
DNA in the human body also affect uoride. In this way, some amount of uoride gets col-
lected in the body tissues. Some amount of uoride is released from the body through sweat,
urine, and defecation. The amount of uoride released from the body also depends on a few
different reasons, such as renal function capacity, hormone levels, age, food levels, weather
conditions (Shyam et al., 2020). Inadequate consumption of uoride (less than 0.5 ppm),
especially in children, causes some health problems, such as:
1. Tooth loss.
2. Reduction in tooth texture.
3. Decreased normal salinization of bones.
Health problems in cold countries like Russia, United States, UK, etc., are related to the
intake of small amounts of uoride. In the above countries, uorine is added to the water to
prevent health problems. In some places, adding uoride to water has reduced dental prob-
lems (Wang etal., 2009).
1.5.2 Adverse effects of excess fluoride
Excess intake of uoride has adverse effects on human based on the following reasons:
1. The amount of uoride present in drinking water.
2. Excess alkaline drinking water and calcium deciency.
6 1. Effects on Human Health due to Fluoride
Green technologies for the deuoridation of water
3. Fluoride intake amount daily.
4. Duration of exposure to uoride.
Pregnant women and lactating mothers are the most vulnerable to the effects of uoride
as uoride in these women enters the baby’s body through ovulation and lactation. Due to
excess of uoride, hormonal irregularities also start in the body (Ando et al., 2001). The
hormones required for the formation and functioning of healthy bones are calcitonin para-
haranone, vitamin-D, and cortizone. Fluorosis, caused by the excess of uoride, is a slow-
growing disease. Fluorosis is of three types:
1. Dental uorosis.
2. Skeletal uorosis.
3. Nonskeletal uorosis.
The primary symptom of dental uorosis is the gradual disappearance of the whiteness
and brightness of the upper surface of the teeth (Enamel). Subsequently, the yellow spots on
the teeth become darker and take the form of brown and black spots respectively. The inten-
sity of uorosis depends on the amount of uoride ingested in the process of tooth formation
(Palmero et al., 1995). Dental uorosis can be divided into three stages: early stage, middle
stage, and nal stage. Fluorosis affects the outer and inner surfaces of the teeth equally. Per-
manent teeth (incisors) and molars are the teeth most affected by uorosis (Pezzi etal., 2001).
Symptoms: (1) Initial condition—white teeth start becoming yellow and the teeth shine.
(2) moderate state—this yellow color starts to appear on the teeth as smooth or in the shape
of the line and gradually the at lines grow on the teeth, which become yellow, brown, and
black, respectively. (3) Final stage—all teeth can be black. After this, there are pits or holes
in the teeth and they break. Breaking of teeth at an early age occurs in areas where uorosis
spreads like an epidemic.
Solution: Teeth affected by dental uorosis cannot regain normalcy because it has become
an integral part of the teeth. Colorless teeth can be protected in the following ways:
1. Bleaching of teeth.
2. Teeth whitening.
3. Plating of teeth.
1.5.3 Dental effect
The small amount of uoride strengthens the enamel of the teeth, which protects the teeth from
infection and decay. For the safety of tooth enamel, it is necessary that the limit of uoride in
drinking water is up to 1.0 mg/L, which prevents tooth decay and does not affect human health
(Prystupa, 2011; Viswanathan et al., 2020). But when the limit of 1.0 mg/L is exceeded, the
human tooth is affected by uorosis. In this disease, it is common to have spots and pits in the
teeth. Children fall under its arrest immediately. Adults also fall under its control if its quantity
in drinking water reaches 1.5 mg/L. Even a little more than this (up to 4.0 mg/L) in the human
body, after going through long-term drinking water, the physical suppleness starts, which
causes stiffness in the bones and joints (Warren, 2021; Cettour etal., 2005).
But if soluble uoride (>2 mg/L) is being ingested continuously during the manufacture
of teeth by drinking water, then the enamel of the teeth starts to become speckled. The main
1.5 Health effects of fluoride 7
Green technologies for the deuoridation of water
function of enamel is the protection of dentin and protecting it from decay and infection, but
in the state of dental uorosis, the protection cycle is broken and there is a serious impact
on the structure of teeth. The natural brightness and beauty of teeth are destroyed when
dental uorosis occurs (Jin etal., 2000; Hu etal., 2012). In the initial stage, the tooth becomes
rough like chalk, which gradually turns yellow, brown, and black. It looks like a thick streak
on the surface of teeth slightly away from the gums. When the disease becomes old, small
holes are formed on the surface of the teeth, which cannot be lled. Dental uorosis occurs
on both the inner and outer surfaces of the teeth and becomes incurable once it is under
arrest. Dental uorosis not only affects physical beauty, but it is also a social problem due to
which marital relationships are also affected, especially on girls’ weddings (Iano etal., 2014;
Levi etal., 1983).
1.5.4 Musculoskeletal effects
Severe uoride results are seen on the musculoskeletal system. Fluoride overdose, mainly
from skeletal uorosis and bone fracture type, has adverse effects on the human body
(Grandjean, 2019). Fluoride slowly reaches the human body and easily gets incorporated into
the crystalline structure of bones. Musculoskeletal system affects the human body in the fol-
lowing ways. Bone fractures
Bone uorosis affects the basic bone structure or bones in the human body. This can happen
to both young and adult. Due to its effect, various joints of the body cause pain. The various
joints where its effect is greater are the neck, arms, and knees, due to which walking becomes
difcult and there is unbearable pain. If the solubility of uoride is reduced to 10–40 mg/L
in drinking water, then the person suffers from bone uorosis (Al-Hiyasat etal., 2000; Choi
etal., 2012). The exibility of joints and bones is removed and there are stability and stiffness.
The most surprising and worrying thing is that bone uorosis is very difcult to detect in
the early stages and is only recognized when it reaches its peak.
In the end, the joints become completely stiff and the spine becomes straight like bamboo.
In such a situation, neither man can bend nor bend. He cannot even bend the shoulder and
fully grabs the bed. He cannot do anything without external support. Sometimes it has also
been observed that the waist of a person affected by uorosis is twisted at right angles and
cannot stand upright (Grandjean and Landrigan, 2006; Shivaprakash etal., 2011). If a person
continues to consume high uoride water, the symptoms of bone uorosis are visible on the
body. This causes distortion in the structural/skeletal system of the person.
It increases bones, inertia in joints, joint pain, and joints exibility end. Fluoride poisoning
causes acute pain, stiffness, and inertia in the cervical (neck) and lumbar (lumbar) joints, the
joints of the knees, and the joints of the hip bone. This is due to abnormal growth in bones
and excessive accumulation of uoride on bones and abnormally increased or shrinking
space between the links of bones (Bergc and Slayton, 2015; Fejerskov and Kidd, 2009). The
following diseases arise due to stiffness and bone malformation in the joints of the bone.
1. Kythosus—Excessive curvature in the thoracic region of the spinal cord, which leads to
posterior elevation.
2. Scoliosis—One side curvature of the spinal cord (spinal cord).
8 1. Effects on Human Health due to Fluoride
Green technologies for the deuoridation of water
3. Paraplegia—Paralysis of the lower part of the body with both legs.
4. Quabriplegia—paralysis in both arms and legs.
Folded exion of the knee joint (asthenia), astro-uorosis affects both children and the
elderly alike.
SymptomsNeck, spinal cord and joint pain, neck, spinal cord and joint stiffness, and
acute hip pain and rmness. Osteoporotic uorosis is an irreversible process, i.e., after suf-
fering from uorosis the disease cannot regain normalcy, but some measures and precautions
can be put into practice to prevent the initial stage of the disease from progressing. Skeletal uorosis
Its effect is also reected on the soft tissues of the human body which is caused by frequent
drinking of uoride-rich drinking water. Common symptoms seen in nonbone uorosis
affected patients are intestinal problems, loss of appetite, leg pain, intermittent diarrhea with
constipation, excessive muscle weakness, excessive thirst, frequent urination, can go a state
of heart attack due to increased cholesterol has also been observed. For this reason, signs of
miscarriage have also been seen (Neville etal., 2015). The Bureau of Indian Standards has
set the standard limit of uoride in drinking water to 1.0 mg/L as per the Indian situation,
while uoride content has been found to be up to 24–41 mg/L in drinking water (ground-
water) in many parts of Rajasthan. It has reached its peak in Andhra Pradesh, Tamil Nadu,
Uttar Pradesh, Gujarat, and Rajasthan, where 50%–100% of the districts have been affected
(Neville et al. 2015; IPCS, 2002).
1.5.5 Reproductive and developmental effects
Since 1990, many publications have published more on the effects of uoride on reproductive
and developmental effects. These studies have focused on structural or functional changes
in the male reproductive tract involving animal models, primarily rodents, and uoride.
High amounts of uoride reproduction and developmentally adversely affect the human
body, reducing the amount of protein in the liver, muscles, and small intestine. Acrosomal
damage and deation, sperm acrosomal acrosine, and hyaluronidase are decient in the
body. Structural and metabolic changes and reduced activity of enzymes in sperm result in
a decrease in sperm count and a signicant decrease in reproductive rate. Nervousness occurs
in men due to spermatozoa being affected by uorosis. Deciency or absence of sperm in
semen causes disease. Lack of testosterone in the blood of those in dominant areas is a
common problem. Drinking water with more uoride is consumed here (Chiba etal., 2012).
1.5.6 Neurotoxicity and neurobehavioral effects
An overdose of uoride directly or indirectly affects the nervous system in the human body,
known as neurotoxicity. Increased amounts can produce neurotoxic disease by interfering
with metabolic processes. Intelligence quotient scores in both men and women declined with
an increasing risk of uoride. Disorders of this type affect 10%–15% of all births. Severe con-
sequences such as loss of quality of life, lack of academic achievement, behavioral distur-
bances result from brain disability. Nervousness, mental depression, tingling, and tremors in
the hands and toes, excessive thirst, frequent urination, etc., sometimes while urinating, the
1.5 Health effects of fluoride 9
Green technologies for the deuoridation of water
amount of urine is less, urine is yellowish red, and there may be irritation (Bergman etal.,
2013; Vandenberg etal., 2012).
1.5.7 Endocrine effects
Since the introduction of community water uoridation in the United States in the 1940s,
sources of human exposure to uoride have increased drastically, and this means that the
likelihood of uoride poisoning cases is also increasing. Fluoride reaches the human body
and affects the human endocrine system leading to serious consequences such as decreased
thyroid function, increased calcitonin activity, increased parathyroid hormone activity, sec-
ondary hyperparatoidism, impaired glucose tolerance (Li etal., 2020; Liu etal., 2021).
1.5.8 Genotoxicity and carcinogenicity
Assessment of genotoxicity represents the key component of the safety assessment of any
substance. Genotoxicity testing involves measuring DNA primary damage that can be
repaired and thus reversible, as well as denitive and irreversible damage (i.e., genes muta-
tions and chromosomal aberrations) that can be generated in germ cells until the next genera-
tion. And disturbances in the mechanisms involved in maintaining the integrity of the
genome. For adequate evaluation of genotoxicity, three main endpoints (gene mutations,
structural chromosomal aberration, and numerical chromosomal aberration) must be evalu-
ated, as each of these events plays a role in carcinogenesis and hereditary diseases.
1.5.9 Some other effects
Excess limit of uoride has affected some organ systems of human-like liver, kidney, gastro-
intestinal system, and immune system. Fluorosis not only affects bones and skeletons but
also affects muscles, red blood cells, digestive system, and ligaments. Fluoride also has its
effect on the soft limbs and the nerves of the body. There are limitless human studies on
drinking water containing an excess limit of uoride in which gastrointestinal effects are
documented. Fluoride also causes various changes in the muscles, resulting in the destruction
of the laments called actin, and myosin in the muscle. The creative association of mitochon-
dria begins to fade. Due to which the patient feels tired and lack of energy in the muscles
(Marinho etal., 2003; Philippe, 2019). Gastrointestinal system
Fluoride in the stomach (stomach) combines with hydrochloric acid (HCI) to form hydro-
uoric acid (F2 + 2HCI = 2HF + Cl2), which is a highly corrosive destructive acid. As a result,
the mucous membranes of the stomach and intestines are destroyed and the cells dry up and
burst (Mahmoud etal., 2020). The following symptoms usually occur in affected patients:
1. Acute abdominal pain.
2. Diarrhea or constipation.
3. Bleeding defecation.
4. Gas in stomach.
10 1. Effects on Human Health due to Fluoride
Green technologies for the deuoridation of water
5. Jitter.
6. Sore mouth.
7. Loss of appetite.
8. Headache.
When uoride is ingested in the body, it also gets collected in the membranes of red blood
cells. As a result, calcium content from the membranes of red blood cells starts to shrink and
the membrane shrinks and takes an irregular shape. In this way, red blood cells take the form
of “amoeba,” which is called echinocyte. The life cycle of the red blood cells in the human
body is 120–130 days, but the echinocyte (macrophages) eats the echinocyte, which they do
not complete their life and the patient has anemia and lack of blood. Due to this process, the
level of hemoglobin in the body decreases (Lombarte etal., 2013).
1.6 Escape methods
No treatment and medicines are available for serious health problems caused by uoride.
Taking precautions is the only solution and it should be adopted as soon as possible so that
no further damage is done.
1. Alternative drinking water source should be adopted which includes conserved use of
rainwater, low uoride (within standard limits), or uoride-free groundwater source
and water from the river, ponds, lakes, etc., to be puried and used for drinking.
2. Such food system should be adopted, where the amount of calcium in its ingredients is
available in abundance. Because it has been observed that in this way the invasion of
dental uorosis can be reduced. Vitamin C quantity has also been shown to be helpful
in ghting uorosis.
3. Various techniques should be adopted to remove soluble uoride in drinking water. The
easiest, effective, and popular among them is the Nalgonda technique in which uoride
can be removed by using alum bleaching powder and lime as pictured.
4. Today, where efforts are being made to awaken the public toward the seriousness of
polio and AIDS and the use of iodized salt, it is necessary to spread information about
uorosis to the people.
For the prevention of uorosis, it is necessary that efforts should be made in a collective
manner and all sections of the society should be included in this work including patients,
public health engineers, hydrologists, policymakers, public general, state governments,
dentist, scientists, researchers, physicians, NGOs (Dey and Giri, 2016; Wong etal., 2011).
1.7 Conclusion
Health has a major impact on the environment and investing in environmental health is a
good investment. Situations such as rapid urbanization, industrialization, globalization,
and population growth put further pressure on the environment. If immediate action is
not taken by all the sectors, the problem may become more serious which may have a
direct impact on human health. Fluorosis is a serious disease that arises from the
Green technologies for the deuoridation of water
References 11
accumulation of uorides in the hard and soft tissues of the body due to long-term exces-
sive intake of uoride through drinking water/food products/industrial pollution. This
results in dental uorosis, skeletal uorosis, and nonskeletal uorosis. Easy identication
of uoride in water can help prevent public health hazards. Other effects of nonescalate
include loss of reproductive capacity, miscarriage, birth of a dead baby, loss of sperm, and
so on. Fluoride can cause kidney failure, kidney stone, retarded intelligence, diabetes, high
blood pressure.
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Green Technologies for the Defluoridation of Water.
DOI: 10.1016/C2020-0-02666-6 17 Copyright © 2021 Elsevier Inc. All rights reserved.
An overview of conventional and
advanced water defluoridation techniques
Saif Ullah Khana, Vinay Pratapb,c, Mohammad Kashif Uddind,
Izharul Haq Farooqia
aDepartment of Civil Engineering, Zakir Husain College of Engineering & Technology, Aligarh
Muslim University, Aligarh, India, bCSIR-National Environmental Engineering and Research
Institute (CSIR-NEERI), Nagpur, India, cAcademy of Scientific and Innovative Research
(AcSIR), Human Resource Development Centre, (CSIR-HRDC) Campus, Ghaziabad, India,
dDepartment of Chemistry, College of Science, Majmaah University, Zulfi campus, Al-Zulfi,
Saudi Arabia
2.1 Introduction
Access to safe drinkable water is a basic right of every human being. With increased indus-
trialization and urbanization, contamination of available water reserves has increased mul-
tifold (Pazand, 2016; Khan etal., 2015). Effective water treatment has become one of the most
critical challenges of the 21st century. The presence of these contaminants either organic or
inorganic, at concentrations beyond permissible limits has degraded the water quality result-
ing in complications to human health (Khan etal., 2021). Fluorine is one of the important
element present abundantly in our environment (Saravanan etal., 2018). Numerous studies
have indicated the correlation between human health issues and emerging environmental
contaminants including uoride (Ali etal., 2021a). Although, presence of uoride in drinking
water is benecial as it strengthens enamel if present in the range of 1–1.5 mg/L, but its
presence beyond the permissible limit of 1.5 mg/L pose serious issues to health (Mohapatra
etal., 2009).
Considering the risk factor, excessive uoride levels posed a great threat to almost two
hundred million people in almost 35 nations worldwide (Ali etal., 2021b). Increased and
prolonged uoride ingestion beyond permissible limits is known to cause dental, bone, and
skeletal uorosis. Numerous studies carried out in past reported that the prolonged con-
sumption of uoride in drinking water supplies with concentration exceeding 1.5 mg/L,
resulted in the development of dental uorosis as mentioned in Table 2.1 along with other
18 2. An overview of conventional and advanced water defluoridation techniques
Green Technologies for the Deuoridation of Water
health effects (Dehghani etal., 2018). Considering the scenario worldwide, masses living in
India, China, and Africa are worst affected by uorosis-related health problems. As far as
the Indian perspective is considered, the population of almost 20 states is affected due to
the excessive ingestion of uoride beyond 1.5 mg/L (Waghmare and Arn, 2015). According
to a report published, poor quality of potable water is known to cause around 80% of the
diseases worldwide, out of which around 65 % are due to endemic uorosis (Ali etal.,
2021b). Therefore, bearing in mind the gravity of problem, various deuoridation techniques
are adopted worldwide to bring the uoride level to acceptable limits. This chapter over-
views the available conventional methods and recent advancements in the ongoing efforts
for uoride removal.
2.2 Conventional methods
Fluoride removal from the contaminated water to bring its concentration within acceptable
limits remains the objective of all the treatment techniques. Most of these techniques have
its limitation with advantages and disadvantages over one another. One of the oldest and
simplest methods developed for deuoridation was the Nalgonda technique named after
the village in Andhra Pradesh, India. It is based on the coagulation-occulation method
involving the addition of lime, aluminium salts, and bleaching powder followed by mixing
to form ocs with subsequent stages of sedimentation, ltration, and disinfection (Waghmare
and Arn, 2015). Apart from its simplicity and low cost, there are few disadvantages as well
due to which this method was mostly adopted at domestic household levels only. The con-
ventional procedures and broad methods adopted worldwide for deuoridation are dis-
cussed in the sections below.
2.3 Chemical precipitation
Chemical precipitation in the treatment of water is the transformation of the state of dis-
solved materials in water to the solid-state. Application of chemical precipitation is found
in the elimination of ionic constituents present in water by the addition of counter-ions for
solubility reduction. One of the common applications of this method is the removal of metal
TABLE 2.1 Effect of fluoride levels due to prolonged exposure in drinking water on human health (Dissanayake,
S.No Fluoride concentration Health effect
1. <0.5 Dental caries
2. 0.5–1.5 Optimum for enamel
3. 1.5–4.0 Dental uorosis
4. 4–10 Skeletal & dental uorosis
5. >10 Crippling uorosis