A New, Old Idea

Mention David Manz, P.Eng. in Bangladesh, Nicaragua or Rwanda and you might receive an approving “yes,” “si” or “qui.” Ten thousand more who don’t recognize the Calgary engineer’s name daily savour the safe, potable water from his inexpensive and elegantly simple BioSand Water Filters.

The Saskatchewan farm boy long knew the value of good, reliable water. However, it took a visit to South Africa in 1988 to nudge him toward developing the filter. The Canadian International Development Agency (CIDA) had contracted the University of Calgary hydrology and computer-simulation expert to work with the University of Zululand to improve the homeland’s water resources. Manz returned from Africa and a similar assignment in the Philippines frustrated by his failure to offer solutions short of boiling or chlorinating the water.

“Here I was, a university professor in environmental engineering, but very little of what I knew could be applied in the context of South Africa or the Philippines,” Manz recalls. He doubted the answer lay in centralized, community-wide systems that left water vulnerable to being re-contaminated between treatment and point of use. He wondered if water could be treated closer to users.

A home-based water-filtering system developed by UNESCO could remove solids but Manz concluded it was “bacteriologically totally ineffective.”

But what about marrying the UNESCO filter with slow-sand filtration? Slow-sand filtration had long been used for community-scale water treatment, starting in England during the 1830s. The technology could remove up to 99% of bacteria by passing a constant stream of water through a bioactive layer and a medium of crushed rock.

Back in Calgary, Manz and some students began “ramping-down” slow-sand filtration by miniaturizing it for household use.

That posed challenges, particularly in maintaining a healthy bioactive layer since homes don’t have constantly flowing water. An immobile column of water even a foot deep above the medium wouldn’t allow diffusion from the air of the oxygen needed to keep the bioactive layer healthy.

Manz asked: “Why not stock it with a shallower layer of water allowing oxygen to diffuse through the water to the biolayer to keep it naturally aerated?”

Retaining just a shallow amount of water above the biolayer created other problems. When untreated water was added, it disturbed and dislocated the biolayer and medium.

Manz’s response was to install a diffuser basin that breaks up the impact of the water as it is poured in. To his surprise, such a diffuser basin had never been mentioned in any of the literature.

So, in 1991, Manz spent $60 to build a prototype, using a garbage can and play-sand as a medium. The BioSand Water Filter (BSF) prototype with a 70 L/hr capacity, was tested at Calgary’s Foothills Hospital. It could remove 98-99% of bacteria, along with parasites, viruses and dissolved solids. The International Development Research Centre in Ottawa commissioned the National Water Research Institute to evaluate the filter. The research found that it completely eliminated all Giardia and 99.99% of Cryptosporidia.

Manz immediately recognized the significance. “Here we had a slow-sand filter that could be stopped and started, and miniaturized. Therefore, we had a technology that likely would work in individual households. I saw that this technology was very important to the wellbeing of the global community.”

Still, funding for further testing and development didn’t flow in easily. Eventually, Dr. Mel Kerr, director of the University of Calgary’s International Centre, arranged to test the filter on a Pan-American Health Organization project. With graduate student Byron Buzunis, Manz headed for Nicaragua. There, with plastic barrels and fixtures bought in local markets, they built 100 L/hr filters and installed them in three households.

“We got bacteria removal from many tens of thousands to just single digits. And the technology was accepted by the people. Local people told us their diarrhea had disappeared,” says Manz.

University Technology International, the U of C’s licensing arm, secured worldwide commercial rights for the patriotically dubbed Canadian Water Filtration Process. Manz — significantly — retained exclusive authority to reassign the BioSand Water Filter’s intellectual property rights for humanitarian purposes.

A further 60 filters were installed in Honduras, Chile and Nicaragua. The locations with filters became the only ones in Nicaragua to eliminate cholera. The success placed Manz in the spotlight and the Association of Professional Engineers, Geologists and Geophysicists of Alberta awarded him its 1996 Project Achievement Award.

Nevertheless, the world wasn’t really beating a path to his door. “Despite its [the filter’s] obvious successes, we couldn’t find the money to support it,” recalls Manz. In frustration he began wondering if it would have been easier to market a totally new concept rather than a new wrinkle for an existing process.

“Slow-sand filtration was considered a developed technology for 170 years. Everybody thought they knew anything there was to know about it. We radically changed it and added another patent, the clean-in-place technology, which allowed cleaning without removing a layer of the media.”

Slowly, hope trickled back.

Manz realized that plastic barrels were not necessarily the way to go, particularly in developing countries. Instead, he designed a wooden mold to shape concrete barrels. The Samaritan’s Purse, a Calgary Christian relief agency, supported the development of a steel mold that was used to build more filters in Nicaragua at about $20 per unit.

Backed by churches and service groups such as the Calgary South Rotary Club, other humanitarian initiatives were started in Haiti and Ethiopia. Manz has delivered dozens of short courses on the system to potential users in Canada and from overseas. Now more than 100,000 BioSand units are installed in 60 countries, everywhere from Brazil’s rainforest to Sudan’s deserts. They serve at least a million people. A current $750,000 CIDA-supported program will build 100,000 household units in Ethiopia.

Though the work was gratifying, Manz found his NGO involvement cut into time needed to build his own business. He had acquired the commercial rights to the filter and he and his wife Nora joined forces (and names) to form Davnor Water Treatment Technologies.

He felt uneasy using his NGO links to promote his own commercial interests. So in 1998, he founded the Calgary-based Centre for Affordable Water and Sanitation Technology (CAWST) to promote humanitarian applications of the BioSand filter.

On the commercial side Davnor enjoyed limited initial success in Canada selling BioSand filters housed in medium-density polyethylene barrels. For instance, the Prairie Farm Rehabilitation Administration demonstrated how an automated 120 L/hr BioSand system on an Alberta farm could filter iron (down to .03 from 1.0 ppm) from groundwater.

Today, there are 12 employees at Davnor’s 1,400-m2 Calgary plant. They build BioSand filter units designed for households ranging from 20 L/hr manual systems to 240 L/hr automatic systems. Davnor has also been developing larger systems. Automated units of 38,000 L/hr capacity, for example, are selling in Canada and in countries such as Nigeria and Colombia where they serve whole villages and communities.

Manz’s persistence is paying off. Last year, Davnor’s sales totalled $1.75 million and the company, now listed on the TSX Venture Exchange, posted its first quarterly profit.

The development of new, larger BioSand systems brings the technology that Manz refined back full circle. Still, Manz sees an ongoing need for the basic, small, easy-to-construct concrete systems that serve individual households. Recently, an enquiry for one came from the University of Pretoria in South Africa, the very place where this Canadian engineer began to conceive the technology 16 years ago.

Nordahl Flakstad is a freelance writer based in Edmonton.