Water desalination system on a bus Tuesday, 19 September 2017

Engineers from the University of Arizona have partnered with Apex Applied Technology to create a mobile water treatment system, effectively a "desalination bus", to an off-the-grid school in a water-scarce Navajo community.

The solar-powered water-purification system and lab on wheels is built into a refurbished operational school bus. The lab offers an added educational component.

The desert portion of the Navajo Nation in northeastern Arizona receives only 18 to 28 cm of rain per year. There is plenty of groundwater but it's high in salinity and in some areas it can be contaminated with metals, including uranium.

According to the researchers, the groundwater, once treated, can be a much-needed source of water for the community.

The multicultural research team, including a number of graduate students, developed the solar water purification system for STAR School, a preschool through eighth-grade public charter school operating completely off-grid in the Navajo Nation near Flagstaff, Arizona.

This is the third water purification system to come out of the partnership between the University of Arizona and Apex Applied Technology, which advocates for federal funding for underserved populations. It is however the first to be built into a bus.

Groundwater is drawn up from wells into a feed tank on the bus. The system then passes it through three filters with progressively lower micron ratings, from 10 to 5 to 1. These filters remove small particles from the water.

Once the particles down to 1 micron have been removed, the water is forced through a series of semi-permeable membranes. 20 per cent of the water pulled in from the well will be filtered into drinkable water, while the rest is returned to the source. The recovery levels have been set low to allow the filtering system to last longer and to keep operations sustainable.

Members of the community and students at the STAR School will learn to operate the low-maintenance system. It is hoped that the students will be inspired to learn more and be educated in STEM disciplines, and that members of the community who train to use the system will find employment.