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4.1 INTRODUCTION
Chlorination produces carcinogenic byproducts like Trihalomethanes and
Halo acetic acids, the development of alternate treatment strategies for the removal
of coliforms are highly essential. It has been proved that synthetic chemicals are not
a safe option for water disinfection where as organic substances bio flocculants are
better suited for water treatment.
Chlorination cannot be totally avoided and can be recommended only at low
dose. Super chlorination is to be avoided and alternate strategies like coagulation
combined with low level chlorination is to be adapted as large scale water treatment
methodologies.
Coagulation and flocculation play a dominant role in many water and
wastewater treatment schemes, including those incorporating membrane treatments.
Because of the complex interdependence of numerous factors inherent in the
coagulation and flocculation processes, a thorough understanding of the phenomena
involved is essential. Rapid development of industrialization and human activities
has lead to increase the discharge of waste and wastewater containing organic and
inorganic pollutants. Bioflocculant is a kind of biodegradable macromolecular
flocculants. The commonly used metal coagulants fall into two general categories:
those based on aluminum and those based on iron. The aluminum coagulants include
aluminum sulfate, aluminum chloride and sodium aluminate. The iron coagulants
include ferric sulfate, ferrous sulfate, ferric chloride and ferric chloride sulfate.
Other chemicals used as coagulants include hydrated lime and magnesium
carbonate.
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The effectiveness of aluminum and iron coagulants arises principally from
their ability to form multi-charged polynuclear complexes with enhanced adsorption
characteristics. The nature of the complexes formed may be controlled by the pH of
the system. When metal coagulants are added to water the metal ions (Al and Fe)
hydrolyze rapidly but in a somewhat uncontrolled manner, forming a series of metal
hydrolysis species. The efficiency of rapid mixing, the pH, and the coagulant dosage
determine which hydrolysis species is effective for treatment. The end product of a
well-regulated coagulation/flocculation process is water in which the majority of the
turbidity has been collected into floc, clumps of bacteria and particulate impurities
that have come together and formed a cluster. The floc will then settle out in the
sedimentation basin, with remaining floc being removed in the filter. The high cost
of treated water makes most people in the rural communities to resort to readily
available sources which are normally of low quality exposing them to waterborne
diseases.
4.1.1 Alum as a Coagulant
Aluminium sulfate or Alum is used as a flocculant to remove unwanted
colour and turbidity from water supplies. It has been used since ancient times for this
purpose and its use together with filtration is standard practice in conventional water
treatment processes around the world. After performing its role the Alum is filtered
from the water but a small fraction dissolves and is not removed. There has been
ongoing debate in the water industry for a number of years regarding the use of alum
in the water treatment process and the ‘suspicion’ that aluminium is linked to
Alzheimer’s disease. The cause of Alzheimer’s disease is subject to international
research. A variety of possible causes have been considered, however, no link
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between aluminium intake and the disease has been established. Aluminium is the
third most abundant element and comprises about 8% of the earth’s crust. It is never
found in its natural form as a pure metal but is always locked in, or mixed with,
other elements as very stable chemical compounds such as alumino-silicates. It
occurs in most rocks, vegetation and soils (such as clay etc) in this combined form.
Aluminium is widely used in many industrial and domestic products including
antacids, antiperspirants and food additives, and in vaccines. It is commonly used in
the food industry as food containers and packaging and many cooking utensils are
made of aluminium. It occurs naturally in many foods. It has been estimated that its
intake from food and beverages is approximately 5-20 mg/day. Research has shown
of the order of 0.4 to 1% of the lifetime body burden of bioavailable aluminium
comes from alum treated drinking water, a minor proportion considering the
relatively large and variable intake of aluminium from food. Hence if a link between
aluminium and health were ever established, significant reduction in aluminium
intake could only result from dietary change. Aluminium concentrations in drinking
water can be reduced by utilising the conventional water treatment practices of
flocculation and filtration. A well operated water filtration plant, even using alum as
a flocculant, can achieve aluminium concentrations in the finished water of less than
0.1 mg/L.
4.1.2 Moringa Seed Powder as a Bioflocculant
Water is a renewable natural resource. Due to ever increasing industrialization,
urbanization, this precious resource is continuously under stress. There are multiple
dimensions to water quality and its deterioration. Water pollution is rendering much
of the available water unsafe for consumption. The pressure of increasing population,
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168
loss of forest cover, untreated effluent discharge from industries and municipalities,
use of non-biodegradable pesticides/ fungicides/ herbicides/ insecticides, use of
chemical fertilizers instead of organic manures, etc are causing water pollution.
Moreover, there are numerous water borne diseases like cholera, diarrhoea,
dysentery etc. which are transmitted by drinking contaminated water. There are
various new water purification techniques which have come up to purify water for
example by using rechargeable polymer beads, using the seeds of Moringa oleifera
tree, purifying water by using aerobic granular sludge technology etc. Research is
being conducted all over the world to develop more and more techniques which can
generate pure water at low cost. All these techniques are being developed to ensure
that in near future everyone will have access to clean and pure water and that too at
an affordable cost.
Moringa is one of the most useful trees in the world; with a huge amount of
benefits. The plant possesses many valuable properties which make it of great
scientific interest. Moringa is reminder of what nature can do, a pure endless natural
resources, and, this is why it is so important to preserve natural biodiversity. The
world map is interesting, as we can check that rural and urban populations can easily
benefit from the assets of the moringa, but also the poorest people by contributing to
their food security, sanitation, drinkable water, and, health. Moringa oleifera is the
most widely cultivated species of the genus Moringa. Moringa is the sole genus in
the flowering plant family Moringaceae. The name is derived from the Tamil word
murunggai or the Malayalam word muringa, both of which refer to M. oleifera. It
contains 13 species from tropical and subtropical climates that range in size from
tiny herbs to massive trees. It is also known as drumstick tree, from the appearance
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169
of the long, slender, triangular seed pods, horseradish tree, from the taste of the roots
which resembles horseradish, or ben oil tree, from the oil derived from the seeds.
The tree itself is rather slender, with drooping branches that grow to approximately
10m in height. In cultivation, it is often cut back annually to 1-2 meters and allowed
to regrow so the pods and leaves remain within arm's reach. In developing countries,
moringa has potential to improve nutrition, boost food security, foster rural
development, and support sustainable landcare. It may be used as forage for
livestock, a micronutrient liquid, a natural anthelmintic and possible adjuvant.
Moringa seeds are rich in proteins and oil, and, are traditionally used for beauty care.
Seeds are also used for water purification. The wood provides a blue dye and it is
used for live fences. Medicinal qualities offer to treat diabetes, to enrich anemic
blood, to staunch a skin infection, to be an antibiotic, to heal gastric ulcers, and, to
care eyes. Thus, this tree offers very interesting opportunities as food supplement,
nutrition, vegetable, oil, water treatment, green manure, foliar spray, natural
fertilizer, livestock feed, fodder, medicine, cosmetic and care products.
Chapter 4
170
Fig. 4.1
Plates showing the different stages of processing of Muringa seed for the treatment of waste water.
Coagulants for Water Treatment
171
The latest research has established that crushed moringa seeds are capable of
attracting and sticking fast to bacteria and viruses that are found in contaminated and
turbid water. The seeds produce positive charges like magnets- attracting negative
elements of bacteria and other toxic particles. This inspired the development of a
revolutionary new natural sanitation water treatment that uses moringa seeds to
purify water. This groundbreaking new discovery is going to revolutionize the
sanitation and water treatment practices and will help to provide clean water
available for all people. The seeds produce positive charges like magnets- attracting
negative elements of bacteria and other toxic particles. This inspired the
development of a revolutionary new natural sanitation water treatment that uses
moringa seeds to purify water. We saw previously that moringa is available in viable
quantities and easy to cultivate in the tropical and semiarid belt. Seed harvested for
water treatment are allowed to dry naturally on the tree and must be harvested in the
dry season (level of polyelectrolyte). Seeds are round with a brownish semi-
permeable seed hull. They have found that when the seeds are dried, crushed and
added to water, the seed powder acts as a coagulant binding the particles and
bacteria. After a short while the coagulated particles, known as a flock, sink to the
bottom and clear water can be poured off. The coagulated solid matter is easily
removed. It works on the basis that when mixed with water the crushed seeds
produce positively charged proteins which attract the negatively charges particles
and bacteria. The mixing action causes them to collide, coagulate and stick to each
other: the seeds naturally reduce the turbidity of the raw water by 90 per cent leaving
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172
clear the water of solids, but also removing 90 to 99 per cent of the bacteria. Now, it
is scientifically proved that moringa seeds, a natural substance locally available from
villagers, give great purification results, with no harmful effects, better as those
obtained with expensive commercial chemicals, as alum
"India is the largest producer of moringa, with an annual production of 1.1 to
1.3 million tonnes of tender fruits from an area of 380 km². Among the states,
Andhra Pradesh leads in both area and production (156.65 km²) followed by
Karnataka (102.8 km²) and Tamil Nadu (74.08 km²). In other states, it occupies an
area of 46.13 km².
The seeds, sometimes removed from more mature pods and eaten like peas
or roasted like nuts, contain high levels of vitamin C and moderate amounts of B
vitamins and dietary minerals Mature seeds yield 38–40% edible oil called ben oil
from its high concentration of behenic acid. The refined oil is clear, odorless and
resists rancidity. The seed cake remaining after oil extraction may be used as a
fertilizer or as a flocculent to purify water. Moringa seed oil also has potential for
use as a biofuel Moringa Seed. The seed of the Moringa tree (Moringa oleifera) is a
natural flocculant/coagulant. That is, when dried Moringa seeds or seed powder is
added to water it helps to treat turbid or cloudy water by pulling together floating
particles-including dirt, other solids, and some germs and worms-and when the
water settles, the particles sink to the bottom of the water container. This method
helps reduce dirt and germs that cause disease and illness, but it does not make the
water completely free of germs and therefore Moringa seeds should not be used as
the only method of treating water. It may be combined with filtration or with solar
disinfection.
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173
Moringa trees can be found in many places because their leaves, wood, and
seed oil are also used as medicine, fire fuel, and food. In addition to the powder
made from grinding dried Moringa seeds, one can use Moringa seed presscakes that
remain after making Moringa seed oil, sometimes called Ben oil. Moringa trees
grow best in dry, sandy soil, and grow quickly. The dried seed powder can only be
used for one water treatment, but is biodegradable, so it is easily disposed after
treatment.
Moringa oleifera is a multipurpose tree with most of its parts being useful
for a number of applications and it is being referred to as the ‘miracle tree’. The
crude Moringa oleifera seed extract is commonly used for water purification at
household level in some areas. For instance villagers in Sudan have been
traditionally using the Moringa oleifera seed to purify water from the Nile River.
Recently efforts are being made to use it for water purification at treatment plants
for community water supply. Several studies have reported the use of crude extracts
from the seed for coagulation. This research has also shown that there are many
plants that need to be screened properly for water treatment. The need to exploit the
potential of plants may offer cheap, and environment friendly methods of tackling
water contamination and may possibly overcome the hazards of using synthetic
compounds.
The coagulative effect of Moringa seeds was even better than with Alum and
this can be explained with the fact that M. oleifera seeds exhibited strong
antimicrobial activity. The raw untreated stagnant water from the gutters or drainage
had an initial total bacterial counts Too Numerous to count, which reduced to only
4000 colony forming units per ml when treated with moringa seed powder.
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174
Moringa oleifera seeds acts as natural coagulant, flocculent, absorbent for
the treatment of drinking water. It reduces the total hardness, turbidity, acidity,
alkalinity, chloride after the treatment. It also acts as a natural antimicrobial agent
against the micro-organisms which is present in the drinking water. The MPN test
had shown positive results which indicated the water samples are faecal
contaminated and not safe for drinking. MPN test reading was reduced after
treatment of higher dose at 150 mg/l of Moringa seed powder. If we can use
combined Moringa oleifera seed powder and chlorine it can give best results and the
water can be suitable for drinking.
Moringa oleifera seed is not giving any toxic effect. It is eco-friendly and
cheaper method of purification of water and therefore can be used in the rural areas
where no facilities are available for the treatment of drinking water. After the
treatment of Moringa oleifera seed, sludge gets settled at the bottom of tank. Large
scale treatment at village level produces large quantity of sludge which can be used
as bio-fertilizers and it becomes an added advantage of this treatment.
Focus on plant research has increased in recent times all over the world and
results have shown an immense potential of some plants in various traditional water
purification system (Amaglah and Benang, 2009). Moringa oleifera is a fast
growing drought, deciduous tree reaching 3 m in height just after 10 months of
cultivation (Valia et al., 1993). Several biological activities have been reported in
the plant including biological coagulation of contaminated drinking water with its
seed (Jahn, 1988; Oluduro and Aderiye, 2007). The use of Moringa seed was once
recommended in Java (Jahn, 1988) and later employed for water purification in rural
villages in Africa and Asia. Earlier studies have found that M. oleifera seed can be
Coagulants for Water Treatment
175
nontoxic and recommended its use as a coagulant in developing countries (Olsen,
1987). Widespread interest in seed propagation of drumstick tree has created a need
for scientific information about the fundamental characteristics of its seeds. Because
of its ability to grow productively in semi-arid environments, agronomists,
nutritionists, and development professionals are increasingly using drumstick tree in
rural tropical and subtropical areas where growers often store seeds in structures
open to the ambient air. Open air storage conditions do not protect seeds from large
fluctuations in temperature and pH levels, which in turn lead to losses of seed
viability. By developing effective seed storage protocols, growers can maintain
viable seed populations from season to season.
4.2 REVIEW OF LITERATURE
Chlorine is known to produce trichloromethane, a cancer precursor
(Yongabi, 2004) while Aluminum sulphate has been linked to Alzheimer’s disease
(Zhang et al., 2006). Furthermore, the cost of purchasing synthetic coagulants and
disinfectants is in hard currency leading to high pricing for treated water in Africa
(Kebreab et al., 2005). Simple technologies such as the application of plant
coagulants such as Moringa oliefera to treat water has been extensively reported
(Olivera, 2001; Jahn, 1988; Muyibi et al., 2002; Yongabi, 2004; Pritchard et al.,
2009). Interest in isolating and purifying bioactive Moringa oleifera coagulant
ingredient has grown and outweighed Zhang et al., (2006). Waterborne and water
related diseases such as diarrhea, typhoid, cholera and drancunculiasis are fast
becoming endemic in certain parts of Africa (Cheesbrough, 1984; Yongabi, 2004;
Pritchard et al., 2009). Yet, the present welldocumented technologies used in water
treatment such as reverse osmosis, ion exchange, uv sterilization,treatment with
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aluminum sulphate and chlorine are becoming unsustainable, unecological efforts on
taking inventory of other potential plant coagulants and disinfectants. The most
important step in water treatment is disinfection. Attention has been focused on
screening plants for coagulant activity (Eilert, 1981; Jahn, 1988; Muyibi et al.,
2002a; Kebreab et al., 2005), but not all coagulants are disinfectant. A study carried
out in India, in which crude ethanol extract of M. oleifera were tested against E. coli,
S. typhii, V. cholera, Shigella dysentriae and Pseudomonas aeruginosa, showed
activity against E. coli only (Shekhar et al., 2000). This study had shown that water
soluble extracts of M. oleifera had antibacterial activity against E.coli. The presence
of oil along many other organic compounds in crude extract increases the content in
organic matter of the treated water (Ndabigengesere, 1998) and prevents its storage
and consumption for more than 24 hours (Jahn, 1988). This fact represents a
disadvantage for its application at full-scale water treatment but can be
recommended for the purification of crude extract (Ghebremichael et al., 2005).
Extraction of seed oil before crude extract preparation can be a suitable purification
option allowing to recover oil for industrial and food procedures and valuates
defatted residues. In view of the fact that most pathogenic organisms are becoming
resistant to antibiotics (Chandana et al., 2005), wide application of greatly under-
utilized trees like M. oleifera would be most desirable to use as safe, inexpensive
and readily available water clarifier and disinfectant.
Moringa oleifera is known to be a natural cationic polyelectrolyte and
flocculant, with a chemical composition of basic polypeptides with molecular
weights ranging from 6000 to 16,000 daltons, containing up to six amino acids of
mainly glutamic acid, methionine and arginine (Jahn, 1986). As a polyelectrolyte it
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177
may therefore be postulated that Moringa oleifera removes hardness in water
through adsorption and inter-particle bridging (LaMer and Healy, 1963). Results of
these preliminary studies have shown that Moringa oleifera seeds have considerable
potential to be used in the treatment of hardwater, especially in tropical developing
countries in rural communities for small scale facilities and/or individual
households.
Moringa oleifera is a natural product, and the chemical constituent and
structure is not fully known. The interaction of the seed with chemical and other
substances in raw water are also not fully understood and the products of interaction
are not all known. Further studies would therefore have to be carried out to provide
insight into the interaction between Moringa oleifera seed suspension and the
constituents of raw water, and the product of the interactions. Information on the fate
of this active agent in treated water is presently not available. Reference may be
made to the results of the study by Berger et al., (1984). In that study it was
concluded that Moringa oleifera seeds as water purifiers may not constitute a serious
health hazard. However, further studies should be carried out to ensure the safety of
the users of this common tropical plant, since when the leaves and other parts of the
plant are used as food. Economic figures are presently not available and there is a
need for studies at pilot scale in order to compare costs, i.e. seed, seed preparation,
storage, etc. Moringa oleifera seed is not giving any toxic effect. It is eco-friendly
and cheaper method of purification of water and therefore can be used in the rural
areas where no facilities are available for the treatment of drinking water. After the
treatment of Moringa oleifera seed, sludge gets settled at the bottom of tank. Large
scale treatment at village level produces large quantity of sludge which can be used
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178
as bio-fertilizers and it becomes an added advantage of this treatment. Bacteria stay
adhered after rinsing and will not transfer to sand Moringa oleifera seeds are also
used as a primary coagulant in drinking water clarification and wastewater treatment
due to the presence of a water-soluble cationic coagulant protein which is able to
reduce turbidity of the water treated. Seeds are powdered and added to the water
straight or after preparing crude extract. Though a number of uses for Moringa oil
has been spelt out, only little information is available on Moringa seed oil extraction.
Previous researchers have extracted Moringa oleifera oil by using different methods
as solvent and aqueous enzymatic extraction (Abdulkarim et al., 2005) but focussed
on the study of the physicochemical properties of the oil obtained. Information on
the influence that oil and oil extraction method could have over the primary
coagulant protein of Moringa oleifera seed extract and its coagulant activity has not
been supplied yet. The current work studies two solvent extraction procedures of
Moringa oleifera oil and its influence over oil yield extraction and coagulant activity
of the extract prepared with defatted seeds. The results of our study allow to develop
an oil-extraction procedure that recovers oil for other industrial purposes and
increases the value of the defatted residues generated in production of a natural
coagulant from Moringa oleifera seeds. Apart from the water purifying qualities,
Moringa leaves are also of high vegetable value. Moringa seeds contain up to 40%
high value cooking oil that can be extracted before using the cake for water
purification.
The seed kernels of M. oleifera contain significant quantities of low
molecular-weight water soluble proteins that carry a positive charge. When the
crushed seeds are added to raw water, the proteins produce positive charges acting
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like magnets and attracting the predominantly negatively charged particles (such as
clay, silt, bacteria, and other toxic particles in water) (Sutherland et al., 1990). Since
bacteria in water are generally attached to solid particles, treatment with Moringa
powder can leave water clear with 90 to 99% of the bacteria removed (Scwarz,
2000; Oloduro and Aderiye, 2007; Amagloh and Benang, 2009; Bukar et al., 2010).
Additional treatment of the water by boiling or adding chlorine is needed to render it
completely safe to drink. Studies carried out to determine the potential risks
associated with the use of Moringa seeds in water treatment has to date not shown
any evidence that the seeds cause secondary effects in humans (Sutherland et al.,
1990). This study had shown that water soluble extracts of M. oleifera had
antibacterial activity against E.coli. In view of the fact that most pathogenic
organisms are becoming resistant to antibiotics (Chandana et al., 2005), wide
application of greatly under-utilized trees like M. oleifera would be most desirable to
use as safe, inexpensive and readily available water clarifier and disinfectant.
4.3 MATERIALS AND METHODS
4.3.1 ALUM TREATMENT
Alum treatment of the contaminated water sample was done according to
APHA (1971). The 100 ml of the water sample was mixed slowly with the
accurately weighed alum and was mixed for 30 minutes .It was kept for
sedimentation and the supernatant was used for further analysis.
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180
4.3.2 PREPARATION OF MORINGA OLEIFERA SEED POWDER
Riped fruits (pods) of M. oleifera were collected from near Mahatma Gandhi
University and near Pandalam area, Pathanamthitta, Kerala during the early rainy
season and cracked to obtain the seeds. The seed were fine powdered for analysis.
4.3.3 Sample Treatment
The seeds were peeled to obtain the nuts and dried in an oven for 1hr.
Thereafter, the dried seeds were ground and preserved in air tight container for
further use.Five different concentrations of the solutions for the loading dose were
prepared by weighing 5.0,10.0.15.0, 20.0, 25.0 mg/l of Moringa powder separately
into a beaker containing 1000 ml of distilled water. The pamba river water sample
with respective concentrations of Muringa seed powder were mixed in beakers and
stirred using a magnetic stirrer to obtain a clear solution and allowed to stand for
half an hour for settling down the contents. A 1000 ml of Pamba river water with no
Moringa powder was kept as the control treatment.
4.3.4 Estimation of COD
The detailed procedure was mentioned in the chapter 2 under the section
materials and methods.
4.3.5 Detection of MPN (Total coliform using most probable number (MPN)
procedure)
In determining the most probable number of coliforms that were present in
each of the treated water samples, the multiple tube fermentation method was
adopted. Lactose broth was used as the medium for the bacteria growth. Two types
of the Mac Konky broth were prepared. These were the single strength broth
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(SSMB) and the double strength lactose broths (DSMB) of 3 tube method were
followed.
4.3.6 FT/IR analysis
The analysis was done at School of Chemical Sciences, Mahatma Gandhi
University, Kottayam.
4.4 RESULTS
Complete elimination of high amount of coliform by superchlorination is
not a safe option for water disinfection. Hence attempts were made to bring alternate
strategies for initial elimination of coliforms contributing to only mild chlorination
towards the end.
Alum is generally accepted as a coagulant and also slightly induces coliform
sedimentation along with suspended solids. In the present attempt alum at different
concentrations were tried and its effect on the COD and MPN of the water sample
was quantified (Table 4.1).
Table 4.1
Effect of Alum treatment on MPN and COD of Pamba river water
Trial Alum Dosage (mg/l) MPN COD mg/l
1 0.0 1390±1.27 19±0.35
2 5.0 1295±1.06 120±0.04
3 10.0 1170±0.98 21±0.042
4 15.0 995±0.35 21±0.35
5 20.0 965±0.63 21±0.282
6 30.0 475±0.49 23±0.12
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182
The initial coliform content was highest with MPN as 1390±1.27 which got
moderately reduced to 965±0.63 on 20 mg/l alum treatment. On increasing the alum
treatment to 30 mg/l, the coliform count was decreased to 475±0.49. ( Fig.4.1).
0
200
400
600
800
1000
1200
1400
0 5 10 15 20 30
Alum (mg/l)
MP
N/1
00
ml
MPN
Fig. 4.2
Effect of Alum treatment on MPN of Pamba river water
On evaluating the effect of alum treatment on COD of the treated sample it
was observed that the COD was not much affected by alum treatment. The initial
COD of the water sample was 19±0.35 mg/l which remained at 21±0.282 on 20
mg/l alum treatment. Even at 30 mg/l concentration of alum treatment the COD
remained almost constant at 23±0.12 mg/l. ( Fig. 4.2).
0
5
10
15
20
25
0 5 10 15 20 30
Alum(mg/l)
CO
D m
g/l
COD
Fig. 4.3
Effect of Alum treatment on COD of Pamba river water
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183
Natural Organic substances are the best and dependable choice for
flocculants. Bioflocculants are the best option for water treatment as they do not
cause any harmful byproducts nor they will be affecting the polluting factors of the
contamibated water.
In the present study Moringa seed powder was used as the bioflocculant.
Moringa seed powder was added at different dosage and its effect on MPN and COD
was evaluated (Table 4.2).
Table 4.2
Effect of Moringa seed powder on TC and COD
Trial Moringa Seed Powder Dosage (mg/l) MPN COD mg/l
1 0.0 1300 17±0.12
2 5.0 1220 17±0.35
3 10.0 760 18±0.19
4 15.0 370 18±0.198
5 20.0 190 18±0.198
6 25.0 36 18±0.198
The initial value of MPN was the highest and the COD was 17 mg/l. Upon
treatment with moringa seed powder the MPN got considerably reduced to 190 at
20 mg/l of moringa seed powder .However the COD remained almost constant at 18
mg/l. 30 mg/l moringa seed powder brought down the MPN to 36 where the COD
remained unaffected at 18 mg/l. ( Fig. 4.3 and 4.4).
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184
0
200
400
600
800
1000
1200
1400
1600
0 5 10 15 20 25
Moringa (mg/l)
MP
N/1
00
ml
MPN
Fig. 4.4
Effect of moringa seed powder on MPN of pampa river water sample
0
5
10
15
20
0 5 10 15 20 25
Moringa (mg/l)
CO
D(
mg
/l)
COD
Fig. 4.5
Effect of muringa seed powder on COD
Coagulants for Water Treatment
185
Fig. 4.6
FT/IR spectrum of pamba river water sample (untreated)
Fig 4.7
FT/IR spectrum of pamba river water sample treated with Alum
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186
Fig 4.8
FT/IR spectrum of pamba river water sample treated with moringa seed powder
Fig. 4.9
FT/IR of the ether extract of Pamba river water sample after chlorination
Coagulants for Water Treatment
187
In the Fig, 4.9 band at 2880 cm-1 indicated Aliphatic CH2,b and at 1258 cm-1
indicated CH2, band at 1100 cm-1 indicated C Cl bond and band at 700 cm-1
indicated the presence of residual chlorine Cl-.
4.5 DISCUSSION
The Pamba river water is heavily polluted with respect to high coliform and
suspended solids. The MPN test had shown consistently positive result which
indicated the water samples as feacally contaminated and not safe for drinking. The
Most Probable Number (MPN) representing total coli forms were extremely high
and represented heavy fecal contamination.
Equally, the water sample carried high value for the suspended solids which
on the other side enhanced the polluting load of the sample. The removal of the
suspended solids is generally regarded as the primary requisite for effectively
treating any contaminated water systems. The most convenient and effective method
of suspended solids removal is by sedimentation. It is based on the difference in the
density between the bulk of the liquid and the sold particles. The settling may be
discrete settling or zone settling. It may be by induced coagulation or by flocculation
with flocculent aids. The coagulation or flocculation mediated sedimentation
facilitates better sedimentation of the suspended matter resulting the co precipitation
of coliform.
Alum treatment of contaminated water is an age old process and extensively
used in the treatment of contaminated water with high amount of suspended solids.
Alum acts as an effective coagulant and often results in the neutralisation of charges
surrounding the suspended solids. The neutralised solids get precipitated and
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188
sedimented along with the coliforms. However alum treatment resulted only in the
moderate removal of coliform which was totally insufficient. Also the effect on
COD was only moderate enhancing it from 19 mg/l to 23 mg/l. Alum itself is a
chemical and any foreign chemical added to water is sure to make a modification in
its organic nature. Even though alum treatment is globally accepted for water
treatment in the primary stage ample scope is there for finding out a suitable
alternative for the same.
Moringa oleifera is known to be a natural cationic polyelectrolyte and
flocculant, with a chemical composition of basic polypeptides with molecular
weights ranging from 6000 to 16,000 daltons, containing up to six amino acids of
mainly glutamic acid, methionine and arginine (Jahn, 1988). As a polyelectrolyte it
may therefore be postulated that Moringa oleifera removes hardness in water
through adsorption and inter-particle bridging (LaMer and Healy, 1963). It was also
observed that the Moringa oleifera seed powder act as an antimicrobial agent against
selected microorganisms. The active antimicrobial agent isolated was found to be 4
alpha rhamnosyloxybenzyl isothiocyanate, and presently known as glucosidal
mustard oil. It coagulates the solid matter in water so that it can be easily removed
and will also remove a good portion of the suspended bacteria.
The adsorption of metals using Moringa is limited to the adsorption surface.
This is because Moringa is a cationic polyelectrolyte of short chain and low
molecular weight (Muyibi et. al., 2002b). Heavy metals and solids have high
charges and Moringa colloidal surface will remove high percentage of metals
compared to other seeds. The mechanism that brings about the adsorption of heavy
metals is through the positive metal ion that forms a bridge among the anionic
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189
polyelectrolyte and negatively charged protein functional groups on the colloidal
particle surface. There is formation of complexes for heavy metals with the organic
matter of Moringa and protein content of seed. Due to its hydrophilic character,
several hydrogen bonds are formed among polyelectrolyte and water molecules
(Oliveira 2001). Polyelectrolyte coagulant aids have structures consisting of
repeating units of small molecular weight forming molecules of colloidal size that
carry electrical charges or ionisable groups that provide bonding surfaces for the
flocs. Adsorption describes attachment of ions and molecules from seed protein by
means of specific mechanisms (Benes and Steinnes 1995). The flocculation
activities of Moringa seeds are based on the electrostatic patch charge mechanism
(Muyibi et al., 2002a). Studies have shown that the seeds have the capability to
adsorb metal cations and attract highly toxic compounds (Muyibi et al., 2002a). A
laboratory study showed that Moringa has the potential to adsorb the heavy metals
from the leachate and from industrial wastewater (Muyibi et al., 2002a). This
research shows that the method can be used for heavy metal removal from drinking
water and wastewater. In this study the local Moringa seeds did not significantly
have toxic effects but aided in improving the water quality for drinking purposes.
The mechanism of coagulation with the seeds of Moringa oleifera consists of
adsorption and neutralization of the colloidal positive charges that attract the
negatively charged impurities and metals in water. The results obtained in this study
were comparable with the performance achieved in heavy metal removal by
previous workers such as Muyibi et al., (2002a) using Moringa oleifera extracts.
Treatment of contaminated water with Moringa seed powder considerably
reduced the coliform count to 35 where it was 450 in the case of Alum treatment.
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More than that alum treatment slightly enhanced the COD where Moringa seed
powder treatment was not found to influence the COD.
The FT/IR analysis of the chlorinated Pamba river water (Fig.4.4) showed all
evidences for the formation of chlorination derived byproducts but there were
indication of modified organic compounds in the case of FT/IR spectrum of alum
treated (Fig.4.7) and Moringa seed powder treated (Fig.4.8) water sample.
Moriga seed powder mediated flocculation results in the aggregation of large
flocs due to slow process of sedimentation. The suspended high amount of coliforms
might have got co- sedimented along with the large flocs formed during the
treatment. The sedimented moringa seed powder along with the sedimented bacteria
could be separated, dewatered, and filter pressed to get ideal soil conditioner and
fertilizer.
Moringa plant are best cultivated in Kerala and the thus the moringa seed
can be extensively collected as a small scale industry, The collected seeds can be
crushed and pretreated to generate moringa seed powder on a large scale basis. This
kind of a new strategy holds grater promise as a small scale industry offering job
opportunities for large number of village women encouraging women empowerment.
The strategy can be adopted in all villages as a special programme on sustainable
basis for the primary treatment of the contaminated water systems. These studies
have confirmed that the seeds are highly effective in removing suspended particles
from water with medium to high levels of turbidity Moringa seeds are less effective
at treating water with low levels of turbidity).