The slimy inner guts of cactus can purify water — new findings that could benefit contaminated water sources used for fish farms, human consumption, and other everyday purposes.
Presenting their work at the American Chemical Society’s 251st National Meeting and Exposition, the researchers found that the mucilage or inner gut of the plant attracted arsenic, as well as bacteria, sediments, 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," explains Dr. Norma Alcantar, one of the study authors and a professor at the University of South Florida.
Based on traditional knowledge, mucilage from the common cactus can perform cleaning action, with Dr. Alcantar herself introduced to the practice by her Mexican grandmother. The old lady used boiled pieces of prickly pear cactus to collect matter in dirty water.
Cacti are sustainable, non-toxic, and edible, even deemed as a delicacy in certain areas.
The team started to investigate cacti’s cleansing benefits in 2006 in the wake of the Haiti earthquake, finding the approach effective in cleaning contaminated water for human intake. They also explored how cacti clean up oil-ridden seawater after the Deepwater Horizon oil rig disaster in 2010 – mucilage emerges as useful oil dispersant.
More recently, the researchers investigated how cactus extract can cleanse aquarium water and those in aquaculture ponds and tanks.
The tanks encourage the growth and proliferation of bacteria, which could lead to smelly compounds including geosmin and 2-methylisoborneol or MIB. The compounds give the water and the fish in it a musty and earthy flavor.
The cactus method is considered an alternative to the practice of purging the tanks with fresh water, which is a long process that consumes huge amounts of water and even stress the fish.
The researchers are currently studying the exact mechanism allowing the inner guts — composed of carbohydrates and around 60 sugars — to perform effective purification. They are now creating a prototype of a recirculating aquaculture model that uses the extract for cleansing.
Watch the video presentation on how cactus guts purify fish tanks.
Photo: Mike Lewinski | Flickr
