Home » Issue 18 » Moringa: the science behind the miracle tree Moringa: the science behind the miracle tree
Submitted by rau on 03 March 2011
A flower from a moringa tree
© WEDC, Loughborough University| Moringas have long been known as miracle trees. Now scientists are investigating their properties in depth, as Sue Nelson andMarlene Rau report.In the foothills of the Himalayas grow trees, five to ten metres tall, with clusters of small oval leaves and delicately perfumed cream-coloured flowers. These are Moringa oleifera – the most widely cultivated of the 14 species of the genusMoringa, known as ‘miracle trees’.“It is called a miracle tree because every part of the tree has benefits,” says Balbir Mathur, president of Trees for Life Internationalw1, a US-based non-profit organisation that provides developmental aid through planting fruit trees, moringas among them. “The roots, leaves, bark, parts of the fruits and seeds – everything. The list is endless.”| Reports in the press about the miraculous nature of the tree may be exaggerated, but it does have some truly impressive properties. Native to northern India but now found widely in Asia, Africa and Latin America, moringas have been used in villages in developing countries for hundreds of years, their uses ranging from traditional medicine, food and cooking oil, to natural pesticide, domestic cleaning agent, and – the latest addition – biofuel. Moringas are extremely hardy, known in parts of Africa as nebedies, meaning ‘never-die trees’, because they grow on marginal soils, regrow after being chopped down, and are one of the few trees that produce fruit during a drought.It is yet another useful property of Moringa oleifera, though, that is exciting scientists: when crushed, moringa seeds can help purify dirty water. This could save lives: the World Health Organization estimates that unsafe water, poor sanitation and inadequate hygiene cause about 1.6 million deaths a year globally.Water purification is mainly a two-step process: initially, water is clarified, removing particles such as minerals, plant residues and bacteria. However, since not all particles readily sink to the bottom, coagulating agents are added to help clump the particles together; these clumps can then be removed by filters or sedimentation. The second step is disinfection, to kill those pathogens that still remain, using chlorine compounds, ozone, hydrogen or ultraviolet light.| M. oleifera seeds are ground to a powder before use
© WEDC, Loughborough University|
Moringa oleifera can help with the first purification step – not only in the developing world but also in the developed world. In industrial water treatment plants, the most prevalent coagulating agents used today are aluminium salts. Most particles that need to be removed from water are charged, so coagulating agents are usually ions; because the coagulating efficiency increases with the square of the coagulating agent’s ionic charge, polyvalent ions such as aluminium are very efficient. However, there is concern – albeit controversial – that long-term exposure to aluminium may be associated with the development of neurodegenerative diseases. Iron salts are an alternative, but they are more difficult to use, as their solubility changes with pH.
Moringa seeds: whole (left) and cut open (right)
© WEDC, Loughborough University| Further kinds of coagulating agents include synthetic polymers, but, as with the other coagulants, the sludge formed in the clarification process needs to be disposed of: so even though synthetic polymers solve the problem of the putative link to neurodegenerative diseases, their lack of biodegradability is an issue.Since M. oleifera is both non-toxic and biodegradable, and reported reductions in the cloudiness, clay and bacterial content of water after the application of M. oleifera seeds rival the efficiency of aluminium salts (seeGhebremichael et al., 2005), it seems to...