<\/p>\n
\nT. Nelson Thompson<\/span> Potable water is indispensable for human life. Where potable water is plentiful, it is often taken for granted. But it should not be forgotten that potable water is indispensable for human life because billions people worldwide are experiencing fresh water shortages. The shortages are certain to worsen in the coming decades.<\/em><\/strong><\/p>\n The humanitarian crisis in Colombia\u2019s La Guajira province<\/a> (about 600 miles north of Bogota) is ample testimony. Between Northeast Colombia and Northwest Venezuela, La Guajira is a dry and windy peninsular desert with a breathtaking ochre and aquamarine coastline. The province is (about half of the size of New York) mainly populated by Colombia\u2019s largest ethnic community, which includes nearly 300,000 members of the Way\u00fau ancestral tribe<\/a>.<\/p>\n For decades their survival has been at risk.\u00a0<\/p>\n Abandonment of the state, corruption, and the misuse of natural resources have impoverished the region. As a result, the Ministry of Housing here in Bogot\u00e1 has confirmed that 96% of people living in rural La Guajira do not have reliable access to potable water. Global warming, El Ni\u00f1o, and climate change are all now especially in play.<\/p>\n Fresh water on the 700 mile Caribbean coastline coastline is subject to inadequate desalination. \u00a0Greater increases in temperatures, especially inland, and declines in precipitation guarantee that livestock die and water to irrigate crops will continue to be insufficient. Thus, for both the coastal Way\u00fau, and inland, desert Way\u00fau, drought, in addition to widespread water contamination from the El Cerrej\u00f3n coal mine, the lack of potable water contributes to poor hygiene and diarrheal diseases, which, with a diet lacking key nutrients, create a particularly high risk of mortality in children.<\/p>\n The Way\u00fau have a number of ancient traditions and rituals they keep alive, living in dispersed small, isolated social communities. A cluster of four or five \u00a0\u201crancher\u00edas\u201d is typical, where families of upwards of 20 people live inside one mud, hay, and cactus hut. A well, or jag\u00fcey, for extracting and storing water might be shared between between multiple rancher\u00edas, and in times of drought long walks may be necessary to access the nearest water-containing jag\u00fcey.\u00a0<\/p>\n Once water is found it is often turbid, salty, or contaminated.<\/p>\n It\u2019s in this way that a centralized, show case, high energy use, high capacity water treatment facility is a mismatch for the Way\u00fau, who need more dispersed, easy access to economical low-tech solutions for smaller volumes of potable water. The proposed $100 million aqueduct from the Rancheria River, now being endlessly debated in Bogota, is only the latest example of a poor solution.<\/p>\n For many years La Guajira has had hydrologic characteristics that do not allow it to be served well with a proposed network of aqueducts. \u00a0The size of the La Guajira and the semi-nomadic way of life of many communities are often cited. More recently, and more alarming, is that much of the water from the Rancheria River, the proposed inflow for the proposed aqueduct, according to El Cerrej\u00f3n coal mining officials, is not suitable for human or animal consumption, or for irrigating crops. In fact, too much of that river water is being used \u00a0is for environmental dust control measures, as established in the mining company\u2019s Environmental Management Plan.<\/p>\n Thus, a different, more immediate, proposal is to link the seawater of the 700 mile Caribbean coastline to inland La Guajira with desalination. Thermal separation<\/strong><\/p>\n Thermal separation imitates the natural process of the water cycle, evaporation from the ocean, accumulation in the atmosphere, condensation in the form of rain or snow, and harvesting.<\/p>\n For solar-driven thermal application in La Guajira, it would begin by passing salt water, or simply brackish, water through solar collectors and a heat-saving ceramic-lined storage tank, where it\u2019s heated to a boiling temperature, and then is gravity fed to another ceramic-lined storage tank, slowly to be drained on \u00a0steel surfaces which are already hot from solar radiation. Then the evaporation process begins.<\/p>\n A pilot demonstration organized by faculty and students \u00a0Universidad Nacional in Bogot\u00e1\u00a0<\/a>produces about 40 gallons of water a day. Enough for 25 people. \u201cOur interdisciplinary group at designed the self-sustainable plant so the community can operate and manage it,” said student\u00a0Juan Esteban Quintero<\/strong>. Innovation matters. So, as reported in Nature Communications<\/em>, the breakthrough efforts of a team of graduate students at MIT who dramatically reduced the undesirable fouling of salt accumulation with household materials holds the promise of improving reliability.<\/p>\n
\n
\nAugust 1, 2024<\/span>
\n\n<\/p>\n
The most widely used desalination processes are thermal separation-flash distillation and membrane-separation reverse osmosis. Generally speaking, these are not patented processes. Thermal separation uses heat to separate the salts. Reverse osmosis uses micro filtration and mechanical water pressure to push salt water, or salt ions, through a semipermeable membrane.<\/p>\n