Manure as a Water Source for Developing Nations?


Access to clean water is critical for human life and agriculture. From the LifeStraw filtration technology to solar-powered irrigation pumps, engineers seek innovative ways to provide water to communities that otherwise could not get enough. A team of scientists at Michigan State University are developing methods to extract water from another unlikely source: cow manure.

How can clean water come from such a dirty source? The McLanahan Nutrient Separation System, as the engineers call it, works using surprisingly simple principles. “About 90 percent of the manure is water,” noted professor of agricultural engineering Steve Safferman. The process merely separates the water from the other components. Using an aerobic digestion machine, which creates energy from animal waste inputs, the system extracts the existing water and leaves other chemicals behind.

The technology is not yet perfect. The engineers are currently able to get 50 gallons of water from 100 gallons of manure, but they hope to increase the output to 65 gallons. The resulting water has not been proved safe for human consumption, but it is clean enough to nourish livestock and crops.

The McLanahan Nutrient Separation System is set to be sold later this year, and the engineers want to market the system to U.S. farms. However, this technology may have an even greater benefit for farmers in developing nations, especially those with less access to water. Many communities already suffer from water crises; according to the U.N. Human Development Report, 1.2 billion people live in areas with limited amounts of water, and another 1.6 billion face water shortages because they do not have the funds to build wells or get clean water from rivers. By investing in new technology to extract water from manure, foreign aid providers may be able to free up more water for human use.

In addition to providing more water for irrigation and livestock, manure filtration has other agricultural benefits. The technology also stores nutrients found in the animal waste, which can then be used to grow crops. Jim Wallace, a student working on the McLanahan system, reports that their process can “capture a large percentage of the ammonia that would otherwise be lost in the atmosphere,” and ammonia is a common component of fertilizer. In developing nations, this fertilizer would be vital for soil enrichment and could lead to stronger harvests.

Collecting manure and removing the nutrients and other chemicals for storage and later use will also have environmental benefits. A study conducted by the U.S. National Academy of Sciences found that 75 percent of greenhouse emissions from cattle comes from those developing nations, and much of this comes from decomposing manure that is not disposed of properly. Harvesting manure for water and fertilizer will allow farmers to capture greenhouse gases, like methane, and reduce their carbon footprint.

Innovative systems to extract water from manure aid in all aspects of farming and have great potential to help developing countries. Though the technology is still in its developmental stages, further exploration and investment could benefit millions of lives and reduce water shortages globally.

— Ted Rappleye

Sources: Michigan State University, IRIN Global, United Nations
Photo: Wikimedia