CHAPTER 1
INTRODUCTION
Water supply is a basic need required for living creatures and human beings. Safe drinking water is essential to the health and welfare of a community, and water from all sources must have some form of purification before consumption.The method employed depends on the character of the raw water. One of the problems with treatment of surface water is the large seasonal variation in turbidity.
For many developing countries water treatment process involves coagulation, flocculation and sedimentation (which are the processes involved in removing turbidity from water) and disinfection are expensive processes because of the high costs involved and the difficulty in assessing the chemical coagulants including alum.Inorganic coagulants such as alum in combination with lime have been conventionally used for removal of turbidity from surface waters. The sludge formed from such treatment poses disposal problems because of its aluminium content and tend to accumulate in the environment and also because of large volume.Therefore, it is desirable that other cost effective and more environmentally acceptable alternative coagulants be developed to supplement if not replace alum, ferric salts and synthetic polymers. However, there have been studies on the use of indigenous natural coagulants. The use of locally grown and natural coagulants may result in a more sustainable and economically available alternative.
The history of the use of natural coagulants is long. Natural organic polymers have been used for more than 2000 years in India, Africa, and China as effective coagulants and coagulant aids at high water turbidities. They may be manufactured from plant seeds, leaves, and roots. These natural organic polymers are interesting because, comparative to the use of synthetic organic polymers containing acrylamide monomers, there is no human health danger and the cost of these natural coagulants would be less expensive than the conventional chemicals alike since it is locally available in most rural communities of Bangladesh. A number of effective coagulants from plant origin have been identified.
The need for simple, reliable and effective method of water treatment leads to the application of plant materials, including seed coagulants of Moringaoleifera. The Moringaoleifera tree grows in tropical and subtropical regions around the world and its seed have been used in drinking water treatment in small scale. Previous studies indicate that Moringaoleifera is an efficient coagulant for the removal of turbidity in both water and waste water treatment.
The Moringaoleifera is an alternative to the use of inorganic and synthetic coagulants.Disadvantages of inorganic and synthetic coagulants are it cause Alzheimer’s disease and similar health related problems, reduction of pH,high costs production of large sludge volume and low efficiency in coagulation of cold water. Moringaoleifera has potential in water treatment as a coagulant,a soften agent and bactericidal agent. Advantages of Moringaoleifera as a natural coagulant are its low cost,produces lesser volume of biodegradable sludge and it does not affect the pH of water.
Moringaoleifera seeds contain a coagulant protein that can be used either in drinking water clarification or wastewater treatment. It is said to be one of the most effective natural coagulants and the investigation on these kinds of water treatment agents is growing nowadays.
The Moringaoleifera is not used in field because of the some drawbacks of Moringaoleifera as it requires large amounts of seeds for small water treatment plant. Also the settling time is more. If the blended coagulant of Moringaoleifera& alum is used then the drawbacks of alum and Moringaoleifera is reduced and this blend coagulant gives best results, means it removes almost 99.4 % the turbidity. Heavy metals are also present in water which is hazardous to health. Moringaoleifera seed coagulant with double filtration also helps in the removal of heavy metals.
CHAPTER 2
MATERIALS AND METHODS
2.1 MORINGA OLEIFERA
Moringaoleifera (MO), known as Moringa, is full of nutrients and vitamins and is good in your food as well as in the food of your animals. Moringa helps to clean dirty Water and is a useful source of medicines.
Fig.2.1: Moringaoleifera Tree
(Source: Eman N Ali (2009))
2.2 PREPERATION MORINGA OLEIFERA SEED POWDER
Good quality dry seeds of Moringaoleifera were selected from the pods that were collected. The pods collected were allowed to completely dry on the tree (the brown colour pods) because the green pods do not possess any coagulation activity.
The pods length ranged between (40-60) cm, and each pod contained around (20-30) seeds. The seeds coat and wings were removed manually, followed by the grinding of the seeds into a fine powder using a domestic blender, then sieving the ground powder through 250 μm sieve. Figures 2.2, 2.3, 2.4 and 2.5 shows the MO pods, MO seed, de-husked seed kernel and seed powder.
Fig.2.2: Moringaoleifera pods
(Source: Eman N Ali,(2009))
Fig.2.3: Moringaoleifera seeds
(Source: Ravikumar K and Prof. Sheeja A K (2013))
Fig.2.4:Moringaoleifera de-husked seed kernels
(Source: Ravikumar K and Prof. Sheeja A K (2013))
Fig.2.5: Moringaoleifera seed powder
(Source: Ravikumar K and Prof. Sheeja A K (2013))
2.3 AQUEOUS EXTRACT
Aqueous extract was prepared by using 200ml of tap water and 25g of MO seed powder, mixed by a magnetic stirrer for 60 minutes and settled for 20 minutes. Moringaoleifer aqueous extract is finally filtered through 20µm paper filter.
2.4 COAGULANT ACTIVITY TEST
Sedimentation Jar test were carried to determine the coagulation properties of the plant derived coagulants. Onebeaker was used as control and in other beakers varying dosage of MO coagulant was added. Jar tests were conductedon 1000 ml synthetic turbid water samples.The standard procedure was, the samples were subjected to a rapid mixing at 100 rpm for 1 minute, and a slow mixing step at 30 rpm for30 min. The stirrer was then switched off and the flock allowed to settle undisturbed for 30 minutes. The samplesfor residual turbidity measurement were withdrawn using a pipette from a height of 5cm below the surface of eachbeaker, and residual turbidity was measured. Effect of dose of natural coagulants on removal of turbidity alsostudied. Jar test also determines the effective dosage of coagulant to reduce the heavy metal of the sample.
The effect of pH on turbidity removal was also studied by varying pH of turbid water. pH of the suspension wasadjusted to the desired value by adding either 0.1 MHCl solution or 0.1M NaOH solution. Turbidity measurementwas carriedout by ‘GlobeInstrument’ Turbidity meter.pH value of the suspensionwas measured using a pH model meter.
2.5 MULTISTAGE DRINKING WATER FILTRATION
By providing roughing filter pretreatment, suspended solids are decreased. Rapid sand filtration is still a viable method of water treatment most suitable for raw water sources with turbidity and suspended solids. Multistage filtration has been shown to be an efficient and effective drinking water treatment technique for source water with high turbidity, organic matter, and suspended solids.
2.5.1 FILTRATION TEST WITH ROUGHING FILTERS
In vertical-flow roughing filters the water to be treated flows in sequence through the three filter compartments filled with coarse, medium and fine filter material. The size of the three distinct filter material fractions is generally between 25 and 3 mm, and graded, for example, into fractions of 25-16mm, 16-8mm and 8-3mm. Roughing filtration was conducted directly after the coagulation and flocculation processes with Moringaoleifera and separates the suspended solids. Vertical-flow roughing filter was operated at 0.3 to 1.0 m/h filtration rates. The separated solids, which accumulate mainly in the coarse filter fraction next to the filter bottom, can be easily flushed out with the water stored in the filter. Therefore, the use of upflow roughing filter in layers was used.
Fig.2.6: Up flow roughing filters
(Source: Ravikumar K and Prof. Sheeja A K (2013))
2.5.2 Filtration test with rapid sand filter
In rapid sand filters the water to be treated flows in sequence through the three filter compartments filled with coarse, medium and fine filter material. The size of the three distinct filter material fractions is generally between 50 and 0.5 mm, and graded, for example, into fractions of 25-50mm, 13-25mm and 0.5-1mm. Rapid sand filtration was conducted directly after the roughing filtration and separates the last remaining flocs that failed to disappear during roughing filtration. The filtration rate for a rapid filter is 5-10 m/h.
Fig.2.7: Rapid sand filter media size
(Source: Ravikumar K and Prof. Sheeja A K (2013))
2.5.3 Moringaoleifera seed coagulation and double filtration
Double filtration is an efficient and effective drinking water treatment technique for source water with high turbidity,organic matter, and suspended solids.Jar tests were carried out in the following conditions: 1 minute rapid mixing and 10 minutes slow mixing. An up-flow roughing filtration stage was chosen because it is a process with a high efficiency in the removal of light flocs. As a second stage a conventional rapid filter was adopted.
The washing of the roughing filter was carried out through lower drainage, and the washing of the rapid filter was counter current. The bed of the upflow gravel roughing filter was made up of three layers of gravel of different granule measures.
Fig.2.8: Moringaoleifera coagulation and double filtration
(Source: Ravikumar K and Prof. Sheeja A K (2013))
CHAPTER 3
RESULTS AND DISCUSSIONS
3.1 REDUCTION IN TURBIDITY
The jar test operations using MO coagulant were carried out in different turbidity ranges namely higher- (90–120) NTU, medium- (40–50) NTU, and lower- (25–35) NTU of synthetic turbid water. The efficiency of the extract of Moringaoleifera, made them used as natural coagulants for the clarification of water. Doses started from 50 mg/L to 100 mg/L for corresponding six beakers. Turbidity was measured before and after treatment. Moringaoleifera works well in higher-turbidity water than lower and medium-turbidity water. Turbidity reduction increases with increasing doses.
Fig 3.1:Removal of turbidity using various doses of Moringaoleifera
(Source: Wikipedia)
3.2 COAGULANT ACTIVITY TEST RESULTS OF SYNTHETIC WATER SAMPLES CONTAINING HEAVY METALS
Coagulation- flocculation was done using shelled blended, oil extracted and crude extract of Moringaoleifera seed powder. Thesecoagulants were extracted by using a standard preparation method.Optimum doses of 2 g/L coagulants were used for different water samples containing heavy metals concentrations of 5 mg/l. The optimumdosage is the minimum dosage of coagulant corresponding tothe removal of heavy metals present in the water samples. At optimumdosage of 2 g/L of coagulant, the final heavy metal concentrationsreduced considerably, in all foursynthetic heavy metal water samples as shown in Table 3.1.
Table 3.1:Final heavy metal concentrations and the respective increase in turbidity levels after coagulation treatment with filtrated Moringaoleifera coagulant.
(Source: Ravikumar K and Prof. Sheeja A K (2013))
3.3 TEST RESULTS OF SYNTHETIC HEAVY METAL WATER SAMPLES AFTER UPFLOW ROUGHING FILTRATION
Samples of water collected from the outlet of roughing filter were used for analyzing the turbidity and heavy metals. Table 3.2 represents the results of turbidity removal from treated water with various heavy metals of concentration 5mg/l, after upflow roughing filtration. An up-flow roughing filtration stage was chosen because it is a process with a high efficiency in the removal of light flocs. The bed of the upflow gravel roughing filter was made up of three layers of gravel of different granule measures.
3.4 TEST RESULTS OF SYNTHETIC HEAVY METAL WATER SAMPLES AFTER UPFLOW ROUGHING FILTRATION AND RAPID FILTRATION (DOUBLE FILTRATION)
Samples of water collected from the outlet of rapid filter were used for analyzing the turbidity and heavy metals concentrations. Table 3.2 represents the results of turbidity removal, after upflow roughing filtration and rapid sand filtration (double filtration).
Table 3.2: Turbidity (NTU) after up flow roughing filtration and double filtration
(Source: Ravikumar K and Prof. Sheeja A K (2013))
The combined coagulation and double filtration process is an alternative for heavy removal, since the coagulation process is effective in removing metal ions and double filtration complements the process by reducing the turbidity to the limits.The MO seed powder has been termed as potential heavy metal removing agent due to its oxygen and nitrogen donating carboxylate and amino groups.MO seed powder extraction with salt increased the removal efficiency. The adsorption of metals using MO is limited to the adsorption surface. This is because MO is a cationic polyelectrolyte of short chain and low molecular weight. The mechanism that brings about adsorption of heavy metals is through thepositive metal ions that forms a bridge among the anionic polyelectrolyte and negatively charged protein functional groups on the colloidal particle surface. There is formation of complexes with the heavy metals and the organic matter of MO seeds such as proteins.Due to hydrophilic character, several hydrogen bonds are formed among polyelectrolyte and water molecules. Polyelectrolyte coagulant aid 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 surface for the flocs. Adsorption describes attachment of ions and molecules from seed protein by means of specific mechanism. Metal ions in coagulation react with proteins and destroy them in water. Metal adsorption occurs due to the high protein content of the seeds. The flocculation activities of MO seeds are based on the electrostatic patch charge mechanism. Studies have shown that seeds have the capability to adsorb metal cations and attract highly toxic compounds.
CHAPTER 4
CASE STUDY
4.1 INTRODUCTION
About 75% of the present world population lives in the developing countries of the world. About 1.2 billion people still lack safe drinking water and more than 6 million children die from diarrhea in developing countries every year.
Safe drinking water is essential to the health and welfare of a community, and water from all sources must have some form of purification before consumption. Various methods are used to make water safe and attractive to the consumer. The method employed depends on the character of the raw water.
Coagulation-flocculation followed by sedimentation, filtration and disinfection, often by chlorine, is used worldwide in the water treatment industry before distribution of treated water to consumers. Naturally occurring coagulants are usually presumed safe for human health while there is a fear by using aluminum salts that may induce Alzheimer’s disease.
Moringaoleifera is one of the most wide spread plant species that grows quickly at low altitudes in the whole tropical belt, including arid zones. It can grow on medium soils having relatively low humidity. Moringaoleifera seeds are an organic natural polymer.
Jahn (1984) has presented Moringaoleifera as a coagulant after her studies in the Sudan (Jahn, S.A.A. 1984; Jahn, S.A.A. 1988) when she noticed that Sudanese village women used it at home to clear the turbid Nile water. Later, many researchers have reported on the various uses of Moringaoleifera seeds as coagulant and coagulant aid in the last 20 years. Moringaoleifera coagulant has been found to have high coagulation activity only for high turbidity water. The activity is low for low turbid water (Muyibi, S. A. and Evison L.M., 1995). Therefore, it is important to improve the characteristics of this plant by identifying its bioactive constituents, which has high coagulation activity. This is one of the objectives of this study.
4.2 METHODOLOGY
4.2.1 Materials
Dry Moringaoleifera seeds used in this study were collected from gardeners in Serdang area, Selangor Darul Ehsan, Malaysia. The extraction of oil carried out by electro thermal Soxhlet using hexane. The bioactive constituents were extracted from Moringaoleifera using phosphate buffer (0.1M), jar test for measuring coagulation activity, turbidimeter for turbidity measurements, and the river water samples (low, medium, and high turbidity from Sungai Pusu, International Islamic University Malaysia) were collected to apply jar test.
4.2.2 Oil Extraction
The extraction of oil carried out by electro thermal Soxhlet using hexane. The oil percentage was 35% w/w. The dried cake was used in this study while the oil kept for other research work.
4.2.3 Extraction of bioactive constituents
Weighing of 10gm of Moringaoleifera cake, adding of 100ml of phosphate buffer (0.1M) with pH 7.5, mix with gentle stirring at 4ºC for 2hours to extract the bioactive constituents, then centrifuge the contents at 6000 rpm for 30 min, the supernatant was injected to the Ion Exchange column to separate the bioactive constituents.
4.2.4 Jar Test
Jar test for measuring coagulation activity, turbidimeter for turbidity measurements, and the river water samples (low, medium, and high turbidity from Sungai Pusu, IIUM) were used to apply jar test. The turbidity for river water samples were 43.9, 91, and 333 for low, medium and high turbidity, respectively.
Fig.4.1: Jar test for high turbidity river water
(Source: Eman N Ali (2009))
4.3 RESULTS AND DISCUSSION
The processed Moringaoleifera was improved by isolation of bioactive constituents from the seeds as a coagulant/flocculant which gave turbidity removal of 95.5%, 98.5%, and 99.3% for the treatment of river water with low, medium and high turbidity, respectively and by using the dosage tabulated in Table 1.
The results showed that the dosage of coagulant to be added was decreased which means decreasing of sludge volume produced (which consider as one of the main problems associated with using aluminum salts and as a sequence need to be treated with more chemicals).
The residual turbidity for all samples was lower than 5NTU, which is the standard setby WHO for drinking water.
Table.4.1: Jar test results (Source: Eman N Ali,(2009))
Moringaoleifera can be used as a natural coagulant/flocculants alternative to the aluminum and other metallic salts.
CHAPTER 5
CONCLUSION
Moringaoleiferais an environmentally-friendly natural coagulant most suitable for the treatment of water containing undesirable heavy metal concentrations. Based on the experimental test results; the following conclusion can be drawn.
1. The optimum dosage of Moringaoleifera aqueous extract for synthetic water samples containing heavy metal concentrations of 5mg/L was 2g/L and the removal efficiencies were 95%, 93%, 76% and 70% of copper, lead, cadmium and chromium respectively.
2. The process of up flow roughing filtration followed by rapid filtration is suitable for the separation of the flocs formed using Moringaoleifera seed coagulant.
3. It is an eco-friendly technology that is economically more advantageous than other treatment alternatives.
4. In accordance with the above conclusions, it is suggested that aqueous extract of Moringaoleifera seed powder treatment with coagulation and flocculation followed by double filtration (roughing filters followed by rapid filtration) is considered in the event of expansion or construction of small scale waterworks, presuming that an adequate amount of plantations are established.
