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Chapter-4

Coagulants for Water Treatment


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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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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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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.

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Fig. 4.1

Plates showing the different stages of processing of Muringa seed for the treatment of waste water.


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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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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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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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


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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


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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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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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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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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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


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


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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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


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.

Chapter 4

190

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).

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