Coagulation Performance of Moringa Oleifera Seeds Stored Under Different Preservation Conditions

The present study was carried out to investigate the effects of storage temperature and packaging methods on the performance of non freeze-dried and freeze-dried Moringa oleifera seeds powders in coagulation of synthetic turbid water (2005 NTU). Non freeze-dried Moringa oleifera was stored in different packaging namely open container, closed container and vacuum packing. Whilst, freeze-dried Moringa oleifera was stored in closed container and vacuum packing. Each of the packaging was kept in room temperature (30°C to 32°C) and refrigerator (4°C). The turbidity, pH and zeta potential of the water samples, the moisture content and physical appearance of Moringa oleifera were examined at monthly interval for 12 months. The optimum dosages of non freeze-dried and freeze-dried Moringa oleifera were 120 mg/L and 260 mg/L respectively. The difference in optimum dosage is attributed to the usage of Moringa oleifera from different sources. The coagulation efficiency of non freeze-dried Moringa oleifera kept in room temperature significantly reduced from 95.7% to 7% or less in the first month for storage in open container, fifth month in closed container and sixth month in vacuum packing. However, storage in refrigerator may preserve the efficiency of Moringa oleifera seeds powders. In open container, the coagulation efficiency of Moringa oleifera was within 95.7% to 18.6% for 12 months storage. In closed container, it remained its efficiency at 95.7% to 83.0% within 10 months storage but showed degradation to 53.3% in twelfth month. For those stored in vacuum packing, the coagulation efficiency ranged from 95.7% to 85.5% for the first 10 months and degraded to 61.6% in twelfth month. Storage in closed container and vacuum packing in the refrigerator were found to be more appropriate for the preservation of non freeze-dried Moringa oleifera. Whilst after freeze-drying, Moringa oleifera’s coagulation efficiency remained above 70% within the 12 months storage. Comparison between the non freeze-dried and freeze-dried Moringa oleifera revealed that freeze-drying had positive effect on the preservation of coagulation efficiency. The result also indicated a negative correlation between the moisture content and coagulation performance for non freeze-dried Moringa oleifera kept in varying conditions but no correlation for freeze-dried Moringa oleifera. The physical appearance of non freeze-dried Moringa oleifera showed significant changes in colour, texture and solubility in water except for those stored in closed container and vacuum packing in refrigerator. In contrast, freeze-dried Moringa oleifera generally did not show significant changes in physical appearances. The studies also showed that Moringa oleifera coagulants (non freeze-dried and freeze-dried) do not change the pH of the water being treated where pH remained at 5.9 to 6.4. Generally, there are no correlation between the zeta potential and coagulation efficiency of Moringa oleifera. Moringa oleifera applied in pilot scale treatment plant was able to remove 44-48% of the turbidity from water (200 NTU) in the flocculation/ settling tank at the effective dosage of 100 mg/L. The residual turbidity was further reduced below 1 NTU after filtration.

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