CASE STUDY4.1 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.
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.
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.