In an innovated approach to cleaning contaminated water, researchers from the University of South Florida (USF) have turned to the mucliage, also known as the inner "guts" of cacti. It is believed that their methods can be used to improve the quality of water used for drinking and raising farm-grown fish.
"We found there is an attraction between the mucilage of cactus and arsenic," explained Norma Alcantar, one of the study researchers from USF. "The mucilage also attracts sediments, bacteria and other contaminants. It captures these substances and forms a large mass or 'floc' that sort of looks like cotton candy. For sediments, the flocs are large and heavy, which precipitate rapidly after the interaction with mucilage."
Alcantar and her colleagues began investigating the cleansing properties of cacti in 2006. She was inspired to harness the cleansing abilities of cacti after her grandmother used boiled prickly pear cactus to separate particles in sediment-laced dirty water.
Researchers previously took a similar approach to cleaning contaminated water following the Haiti earthquake and found that it worked well. Cactus mucilage also proved to be an effective oil dispersant.
In the latest study, researchers investigated if cactus extract could clean recirculating aquarium water, as well as water in aquaculture tanks and ponds. Alacantar and Tunan Peng, a graduate research assistant in her lab, explained that these tanks create conditions that encourage the growth of bacteria, which in turn makes farm-grown fish - a major food source worldwide - taste or smell unpleasant.
Current methods used to cleanse the fish involve purifying the fish with fresh water at harvest. However, this method is not favorable, as it takes months to complete and requires a lot of water. Researchers also note that it stresses the fish.
However, the USF scientists are still unsure what exactly about the cactus mucilage makes it such an effective purifier. They plan on investigating the chemical composition of the mucilage, which is made up of carbohydrates and sugars.
Alcantar and Peng are currently working to create a prototype of a recirculating aquaculture system that uses cactus extract as a cleansing agent. They recently presented their findings at the 251st National Meeting & Exposition of the American Chemical Society.
