Draff to dram: water cleanser created in chance study of whisky byproduct


Mark Tran

Leigh Cassidy explains how her grain research led to a system which can purify water poisoned by arsenic in Bangladesh

A project to remove arsenic from groundwater in Bangladesh began by accident, when Dr Leigh Cassidy from Aberdeen University was working on technology to treat industrially contaminated water in the UK.

Cassidy, who was working on her Phd, thought draff, the residue of barley husks that is a byproduct of using grain in brewing alcohol products such as whisky, would act as a cleansing agent. The idea was brusquely dismissed by one colleague.

"I was told 'don't be stupid it will never work'," Cassidy says. "But someone else said to go ahead."

Cassidy did indeed go ahead, modifying the draff with a secret ingredient, transforming it into a cleansing agent. She is now credited as the inventor of the appropriately named Dram – she admits to trying to think of a clever name. Dram is short for device for the remediation and attenuation of multiple pollutants. Instead of using draff in Bangladesh, Dram will use local ingredients such as coconut shells or rice husks to act as the organic filter media that traps the arsenic.

The arsenic crisis in Bangladesh is considered by the World Health Organisation to be the largest mass poisoning of a population in human history. About 77 million people are at risk of arsenic poisoning despite the hundreds of millions of dollars spent in addressing the problem. One in five deaths in Bangladesh are due to arsenic poisoning.

Dram works using a stainless steel unit connected to contaminated water in a tubewell. The water is pumped into the bottom of the unit where it rises up through a bed of the organic filter media, binding the arsenic. Clean water is displaced and forced out of the top of the unit and through the built-in tap.

PurifAid, a Canadian social enterprise based in Toronto, Canada, founded by Shahreen Reza, who is of Bangladeshi origin, is working with Brac, the Bangladeshi NGO, to deploy Dram in Bangladesh. PurifAid is using a $100,000 (£60,000) award from Grand Challenges Canada to start the project in Bangladesh as soon as the political situation calms down. Tension is high in the country before the scheduled January elections.

Reza had been thinking of a water purification scheme for Bangladesh ever since she was a student at the prestigious Institut d'Etudes Politiques in Paris in 2010 and found out about Dram on the web. She is drawn to the device because of its simplicity and requires no change in behaviour from villagers.

"The water is decontaminated at a rate of 1,000 litres an hour, which is at industrial levels," Reza says. "The filter, which must be replaced every four to six months, can be used as biofuel and the units only need a simple cleaning every four to five months."

PurifAid plans to use a franchise business model for Dram. Local villagers will filter and deliver purified water, perform maintenance, acquire new filters, and dispose the used ones. Dram's designers say it removes 95% of arsenic from contaminated water within five minutes of exposure and claim it is cheaper to manufacture than existing alternatives such as the Sono Filter, the market leader, which sells for about $40.

No price has been decided yet for Dram, but it is expected to cost about $10. Villagers are expected to invest collectively to purchase, install and operate Dram on existing tube wells.