TW Viewpoint | Cattails Eco-Heroes

October 4, 2017 | Stuart Wachowicz

With a global population now over 7 billion, mankind produces a lot of waste. Is there a natural, sustainable solution to our growing sewage dilemma?


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On the rolling Saskatchewan prairie, about 70 miles east of the city of Saskatoon, sits a pleasant community of 6000 people named Humboldt. It was here that in the late 1970's and early 1980's, a remarkable scientist conducted an equally remarkable experiment, the results of which improved many communities around the world.

All communities are faced with the constant challenge of safely disposing of sewage. Sewage treatment that will render effluent harmless to the environment is actually very expensive. In many places the cost is such that effluent is simply dumped in rivers, lakes or seas. One only needs to think back to the Rio Olympics in Brazil to illustrate the devastating effect of such practices.

Dr. G. Lakshman, a researcher at the Saskatchewan Research Council in the 1970's and 80's, was acutely aware of the problem.

Humboldt needed a new treatment plant that it could not afford. Lakshman was given permission to develop two very small and very shallow lagoons outside of the community. In its carefully designed 8-inch deep trenches, workers planted thousands of cattails or bulrushes. Lakshman believed that marsh plants in general, and cattails in particular, had insatiable appetites for sewage, and were perhaps the root of the solution for waste treatment in such areas. He reasoned such plants normally exist at the bottom of drainage basins, and are at the receiving end of all the material that eventually gets washed into low areas by rain and gravity.

Lakshman's report explains that the reed's capacity for neutralizing the harmful effects of pollutants like nitrates and phosphates borders on the miraculous. Most plants absorb only the nutrients they require, but cattails take in as much as they can get. The Research Council's report reveals how effectively the reeds handle waste. It identifies, for instance, the special antibiotic secretions released by the cattail that neutralizes fecal bacteria, including e-coli and coliform. The absorption and neutralization of dangerous chemicals was noted. The report explains that the plants can even fix heavy metals such as mercury, phenols, cyanide, zinc and break down hydrogen sulfide. They were observed to even render harmless runoff containing pesticides and herbicides.

The speed at which the plants worked was astounding. The little lagoons could process 12 months of sewage in six months. The actual neutralizing cycle took only 21 days, and the released water, after 21 days in the lagoons, was found to be comparable with the water in some of Saskatchewan's cleanest lakes.

It was also noted that with modern sewage treatment plants there was still the problem with odour, yet in the Humboldt study it was noted that the effluent quickly became free of foul smell. The mechanism that causes this is not yet known. When we think of swamps we often think of mosquitos, but the study also shows the cattails secrete a larvicide from their root which kills mosquito larvae.

As a result, the Saskatchewan government began to recommend feedlots and farm operations leave wetlands undeveloped, and plant cattails in dugouts, ditches and in zones of low gradient drainage to render runoff harmless. Even more amazing is the fact the reeds, despite their rather obnoxious diet, by the end of the growing season are safe to harvest and use for animal feed.

Essentially, these aquatic plants improved water quality by making significant reductions in PO4(phosphate), N (nitrogen), BOD (biochemical oxygen demand), and fecal coliforms in only a three week period. (Lakshman 1983)

Even more dramatic improvements in water quality have been documented by other researchers.

"...Root excretions of many wetland plants have also been shown to be a mechanism for either partial or complete elimination of disease-causing bacteria. In fact some plant species have been known to reduce fecal indicator and pathogenic bacteria by up to 90 percent after only two hours contact (Seidel1976)." R. Russell (1987) "Wetlands and Water Management", Canadian Water Resources Journal (Jan 2013)

In another Saskatchewan community, that of Vonda, a similar project has been operating since 1983. The mayor, Dan Sembalerus stated: "The system has been trouble-free, requiring no changes or modifications." (R. Lyseng, "Are wetlands Mother Nature's outhouse, or do they deserve more respect?" The Western Producer, Jan 8, 2015)

In our rushed world, with its fixation on modern technology we so easily overlook the design that is crafted into the planet on which we live. It is truly folly to write off all that exists as the work of chance, especially when we reflect on the cycles that are all around us in nature. The mechanisms to deal with toxins and waste were not overlooked, as the miraculous chemical digesters we know as the cattail and the bulrush are considered. They labour free of charge, do excellent work and never go on strike. When we take a moment to stop and reflect on aspects of how the earth functions, design is obvious.

I am Stuart Wachowicz for Tomorrow's World Viewpoint.

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