TRUST ZONE

'Cactus extract can purify contaminated water'

The technology makes use of century-old knowledge that mucilage from some common cacti can clean drinking water. Using boiled prickly pear cactus to capture particles in sediment-laced dirty water makes the sediments sink, and the water at the top of the bucket becomes clear and drinkable,researchers said.

"We found there is an attraction between the mucilage of cactus and arsenic," said Norma Alcantar, from the University of South Florida (USF) in US.

"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," Alcantar said.

Common worldwide, cacti are a sustainable product and are not only nontoxic, but are edible and considered a delicacy. Cactus mucilage was found to be an effective oil dispersant, and could be used to clean up oil spills from seawater, researchers said.

The researchers found that cactus extract could clean recirculating aquarium water, as well as water in aquaculture tanks and ponds. They are currently studying the chemical composition of the mucilage, which is made up of carbohydrates and some 60 sugars, with the goal of synthesising it in a lab.

They are developing a prototype of a recirculating aquaculture system that uses cactus extract as a cleansing agent and they will conduct a life cycle analysis of the system.