18
M. Al-Sahari et al.
which can disrupt treatment and water refining systems and outbreaks of deadly epidemics such as Cholera epidemic (Al-Gheethi et al. 2018; Wurtsbaugh et al. 2019;
Williams et al. 2019). Wastewater of textile, slaughterhouses, and chemical industries
that receive high attention from researchers are the most common sources of natural
water contamination due to its high content of organic and inorganic matters and low
degradability under the natural conditions in addition to its unique characteristics in
developing the bacterial strains and viruses (Deghles and Kurt 2016; Pahazri et al.
2016). Over the past years, many techniques have been used to treat various types of
wastewater, including physical and chemical biological techniques, which still have
a high performance on wastewater treatment. However, there have been many issues
such as the high cost of chemical processes, the secondary pollution resulted from the
excessive utilization of chemicals and the high production of industrial and domestic
wastewater that have forced researchers to find alternative treatment methods for
these techniques to achieve the optimal efficiency of environmental treatment and
control the massive quantities of generated wastewater. Global emphasis on environmental conservation and the strict regulations have forced researchers and many
countries to develop the wastewater treatment systems to comply with the global
standard where many studies and applications have been performed on the alternative utilization of the natural coagulants for the flocculation process of wastewater
which have shown high efficiency in terms of processing cost and treatment performance comparing to the chemical coagulants. The chapter reviews a summary of the
coagulation/flocculation processes using natural coagulants as well as reviews one
of the most effective natural methods of water and wastewater treatment.
2.2 History of Coagulants Utilization
The utilization of coagulants in wastewater treatment is an ancient process goes
back thousands of years, and it has developed throughout the ages until sophisticated utilization of the coagulation processes were achieved during the last century
when ferric chloride and aluminium sulphate were used as coagulants widely in
wastewater treatment plants. The theory of particle collision function was developed in 1917, which was considered as a reference to explain the concept of the
changes in the number of particles in the flocculation process, this initiative came
after Schultz–Hardy suggested to clarify the mechanism of coagulation. In 1928,
Mattson (2002) discovered that the aluminium and iron hydrolysis products were
more important than the trivalent ions themselves. Several studies have been conducted in 1934 to investigate the effects of pH and the diversity of anions on the floc
formation time. The following studies focused on finding better coagulants and on
the mechanical methods of producing better flocs. Langelier and Ludwig (1949) have
created a new coagulation theory relied on two distinct mechanisms to remove the
colloidal impurities which are the double-layer compression and precipitate enmeshment. Double-layer compression mechanism known as the process of agglomerate
and precipitate resulting from the domination of particles over the repulsive forces,
M. Al-Sahari et al.
which can disrupt treatment and water refining systems and outbreaks of deadly epidemics such as Cholera epidemic (Al-Gheethi et al. 2018; Wurtsbaugh et al. 2019;
Williams et al. 2019). Wastewater of textile, slaughterhouses, and chemical industries
that receive high attention from researchers are the most common sources of natural
water contamination due to its high content of organic and inorganic matters and low
degradability under the natural conditions in addition to its unique characteristics in
developing the bacterial strains and viruses (Deghles and Kurt 2016; Pahazri et al.
2016). Over the past years, many techniques have been used to treat various types of
wastewater, including physical and chemical biological techniques, which still have
a high performance on wastewater treatment. However, there have been many issues
such as the high cost of chemical processes, the secondary pollution resulted from the
excessive utilization of chemicals and the high production of industrial and domestic
wastewater that have forced researchers to find alternative treatment methods for
these techniques to achieve the optimal efficiency of environmental treatment and
control the massive quantities of generated wastewater. Global emphasis on environmental conservation and the strict regulations have forced researchers and many
countries to develop the wastewater treatment systems to comply with the global
standard where many studies and applications have been performed on the alternative utilization of the natural coagulants for the flocculation process of wastewater
which have shown high efficiency in terms of processing cost and treatment performance comparing to the chemical coagulants. The chapter reviews a summary of the
coagulation/flocculation processes using natural coagulants as well as reviews one
of the most effective natural methods of water and wastewater treatment.
2.2 History of Coagulants Utilization
The utilization of coagulants in wastewater treatment is an ancient process goes
back thousands of years, and it has developed throughout the ages until sophisticated utilization of the coagulation processes were achieved during the last century
when ferric chloride and aluminium sulphate were used as coagulants widely in
wastewater treatment plants. The theory of particle collision function was developed in 1917, which was considered as a reference to explain the concept of the
changes in the number of particles in the flocculation process, this initiative came
after Schultz–Hardy suggested to clarify the mechanism of coagulation. In 1928,
Mattson (2002) discovered that the aluminium and iron hydrolysis products were
more important than the trivalent ions themselves. Several studies have been conducted in 1934 to investigate the effects of pH and the diversity of anions on the floc
formation time. The following studies focused on finding better coagulants and on
the mechanical methods of producing better flocs. Langelier and Ludwig (1949) have
created a new coagulation theory relied on two distinct mechanisms to remove the
colloidal impurities which are the double-layer compression and precipitate enmeshment. Double-layer compression mechanism known as the process of agglomerate
and precipitate resulting from the domination of particles over the repulsive forces,