There are around 1.8 billion people lack consistent access to clean water and some 2.4 billion people who access to appropriate sanitation. According to the World Health Organization, there are also risks from diarrheal disease resulting from poor water quality. Diarrhea is the second leading cause of death in children aged under five years old. Each year the UN Agency estimates that diarrhea kills about 525,000 children aged under five. Infection is spread through contaminated food or drinking-water, or from person-to-person, by bacteria.
Carnegie Mellon University researchers have developed a method to help combat the lack of clean water in certain regions of the world. This is a new process to help refine water, based on sand and plant materials. The important aspect is that the necessary materials are available in low income countries. The new water filtration medium has been dubbed “f-sand.”
What’s also interesting about f-sand is that it uses proteins from the Moringa oleifera plant. The plant is a fast-growing, drought-resistant tree, native to the southern foothills of the Himalayas in north-western India. It is widely cultivated in tropical and subtropical areas. Here its young seed pods and leaves are used as vegetables; also, several parts of the tree are used in traditional herbal medicine.
The plant material can be used for water purification. However, an unmodified approach results in high amounts of dissolved organic carbon. This means that microbes can grow readily, within 24 hours. This means the water is only fit for human consumption for short periods of time.
A researcher called Stephanie Velegol had the idea to combine the plant-based water purification technique with sand filtration methods (which are already common in regions with unsuitable drinking water).
Creating f-sand
Velegol conducted studies where she showed that by extracting seed proteins and then adhering them to the surface of silica particles (taken from sand) it was possible to create what became f-sand.
Trials showed how f-sand has microcidal properties and it can also reduce the turbidity of water, leading to water with goof clarity and with reduced particulate and organic matter. Moreover, through the process undesirable contaminants and dissolved organic carbon can then be washed out.
This means that the water can be left for longer, increasing its expiry time. A further advantage with the process is that the f-sand can be reused. This wasn’t the end of the inquiry, however, as the researchers strove to improve the effectiveness.
Biomedical Engineering and Chemical Engineering professors Bob Tilton and Todd Przybycien undertook experiments to see whether isolating certain proteins from the M. oleifera seeds could increase f-sand’s effectiveness?
Here they discovered, as Laboratory Manager reports, that the seed of M. oleifera is composed of least eight different proteins. By separating these proteins through fractionation these could have allowed more focused protein selection and by isolating certain proteins this might have provided a more efficient finished product.
Increasing concentration
However, fractionation was not the answer. The parameter of the f-sand manufacturing that turned out to be important was the concentration of seed proteins required to create an effective product. The researchers calculated that the means to achieving the proper concentration was by ensuring that there were sufficient positively charged proteins to overcome the negative charge of the silica particles to which they are attached. In other words, the need to create a net positive charge. The positive charge turned out to be important as to attract the negatively charged organic matter, particulates, and bacteria contaminating water.
The end product should provide low income nations with a low-cost and accessible form of water purification.
The research has been published in the journal ACS Langmuir and the research paper is titled “Moringa oleifera Seed Protein Adsorption to Silica: Effects of Water Hardness, Fractionation, and Fatty Acid Extraction.”
Essential Science
This article is part of Digital Journal’s regular Essential Science columns. Each week Tim Sandle explores a topical and important scientific issue. Last week we considered a new study into sodium levels and diet, which indicated that there is a clear association with sodium levels and disease. The new research sends out a new warning.
The week before we looked at a computer program that can look five minutes into the future. The artificial intelligence was developed at the University of Bonn, and it appears to be able to accurately predict future actions.
