Desert dwellers needing to treat their drinking water have the means close at hand. A biochemical engineer at the University of South Florida in Tampa has found that the mucilage of the prickly pear cactus, the clear, viscous liquid within the cactus pads, can effectively treat water for arsenic, bacteria, and cloudiness. The mucilage helps the cactus survive by sealing water within the plant.

According to a Sept. 17 article in Discovery News, Norma Alcantar became aware of the unique qualities of the cactus from her grandmother's folk wisdom; she was a native of north-central Mexico. Her grandmother used water left over from boiling prickly pear cactus pads, eaten as salads and in other dishes, to clear up cloudy river water to be used for cooking or drinking.

Alcantar found that mucilage binds to the dirt causing particles to coagulate; large clumps are then formed that settle out of the water. According to the article, further research found that the mucilage can form a complex with arsenic large enough to be removed with a sand filter. Alcantar reports that arsenic removal ranges from 80 percent to lower than 50 percent, with the percentage of removal determined by the amount of arsenic in the water supply.

Further, Alcantar's research team also has demonstrated that mucilage can remove bacteria from water by either engulfing the bacteria, thereby starving them or causing the bacteria to bind and settle out of the water.