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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.
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