A pointed solution to water contamination

An article at the Discovery Channel site says prickly pear cactus can be used to remove arsenic from water.

 

The slimy ooze inside prickly pear cactuses that helps the plants store water in the desert can also be used for scouring arsenic, bacteria and cloudiness out of rural drinking water, according to research at the University of South Florida in Tampa.

Biochemical engineer Norma Alcantar first learned of the cactus's unique abilities from her grandmother, a native of north central Mexico. There, the residual water from boiling the flat, oval-shaped lobes of prickly pear for salads and other dishes was used to clear up cloudy water drawn from the river before use for cooking or drinking.

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Then, she turned her attention to other water contaminants. The group's more recent research has shown that the mucilage can also form a complex with arsenic, a carcinogenic water contaminant that can occur naturally or from industrial or agricultural pollution.

The arsenic-mucilage complex is large enough that it can be removed by drawing the water through a sand filter.

"Sometimes we get 80 percent removal, and sometimes we get lower than 50 percent removal," Alcantar said. "We don't yet know exactly what it is; we haven't found what are the exact best conditions for the mucilage [to get the most arsenic removal]."

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Alcantar estimates that one lobe of prickly pear would supply a family of five for about five weeks. Alcantar's team is still optimizing and developing the best system, but she envisions that each family would pass their water through a filter that would periodically be recharged with fresh mucilage from prickly pear grown at home or in the community.