Floating Cattail Bioplatforms -- YES!!!!

by Eric Rempel

It is exciting to follow developments with respect to the Landmark and Niverville lagoon reclamation projects. Both are using swamp vegetation to remove phosphorous from their lagoons. Equally exciting are trials at Providence University College to use dried cattails to heat the campus. All three projects have been reported by The Carillon and other local media.

These reclamation technologies are intended to address the challenge faced by all municipalities; namely, how to dispose of phosphate.

There was a time when all cities, all towns, simply flushed the chemicals found in their liquid waste into the nearest waterway, implicitly assuming it was gone once they had done that. The concern at that time was with coliform bacteria; bacteria that spread disease, and it was assumed that if the liquid sewage going into the waterway was coliform free, if it had been treated to that effect; it was safe. And to a significant extent it was. Thanks to this approach to liquid waste-water treatment we, in the industrialized countries, have more or less removed the threat of disease spread through human waste.

But gradually we have come to realize that there are chemicals in our liquid waste that are not as benign as we had assumed.

First we came to the realization that nitrogen in waste water resulted in an undesirable algae bloom in waterways. Nitrates in water also had other negative effects. This was not so hard to deal with, because there are ways of converting nitrates in water to free nitrogen which is what the air we breathe is mostly made up of. So we progressed and we discharged liquid free of coliform bacteria and free of nitrates into our waterways.

Then came 1999. A new algae bloom occurred on Lake Winnipeg and this one was directly attributed to phosphorous discharge into that lake. Lake Winnipeg was dying, we were told. Manitoba was galvanized into action. Farmers and municipalities are no longer allowed to discharge phosphorous laden water into waterways. Manitobans suddenly realized that water with chemicals in it, particularly water carrying phosphorus was not benign.

So towns and cities in Manitoba now need to deal with the phosphorus in their lagoons. That phosphorus comes primarily from the food we eat. It is added to the liquid waste stream when we flush the toilet. Conventionally, today, that phosphate is dealt with by adding alum to the liquid in the lagoon. The alum precipitates the phosphorus so it settles in the bottom; and the liquid, which is now phosphorus free can be drained off. The remaining sediment is buried in our landfills.

But this is expensive and many of us wonder about the long term effect of that buried phosphorous. As we seek to leave a better world for our children and grandchildren, is it really wise to simply bury our unwanted phosphorus?

So I find it refreshing that these local municipalities are exploring other ways of dealing with this phosphorous. They are likely to save money, but more important, they are potentially turning a pollutant into a highly desired, potentially scarce product. 

So that's one side of phosphorous -- it is a serious pollutant. But there is another side. Phosphorous is also an essential plant nutrient.

Phosphorous is essential to life. Without phosphorous a plant will not grow. From time immemorial, farmers have known that applying manure to land enhances plant growth. I well remember riding with my father-in-law, he would get a whiff of manure: “It smells like money” he would say. Prior to the modern scientific era, farmers did not know what in manure promoted plant growth, but they knew that the reliable way to increase crop growth was the application of manure.

Today we know that of the minerals plant need for healthy, vigorous growth – the minerals most likely to become deficient when the land is cropped – are nitrogen and phosphorous.. Science identified these deficiencies about 150 years ago, and during the inter-war period industrialists working with scientists found ways of isolating and distributing these minerals in concentrated form. Since the 1950s we all have become increasingly dependent on these concentrated mineral fertilizers – farmers directly, and we who all depend on farmers for food are indirectly dependent on these phosphate fertilizers.

So we now find ourselves part of a massive system that 1) mines phosphate rock, 2) trucks this phosphate to farmer's fields where it nourishes crops, 3) removes the phosphate from the fields through harvest, 4) trucks the harvested food to the cities and towns where it is consumed, 5) deposits the phosphate into our toilets where it is flushed, and 6) makes its way to our lakes and waterways were it becomes a serious pollutant.

Reflection makes it obvious that this system is neither sustainable nor rational. For one thing there is a limited supply of phosphate to be mined. The most accessible phosphate has already been used up (google peak phosphate). We will experience shortages. We just don't know when. Furthermore all that transportation is inefficient, and possible only because of cheap fuel. And finally how long can we continue to bury phosphorous we flush down our toilets as a pollutant?

But it need not be that way. There are alternatives. There are ways of removing the phosphorous from our waste stream and applying it to our land as a fertilizer. It just needs the political will. And what is excites me today is that the towns of Landmark and Niverville seem to have the political will to explore one of those alternatives. At this time the technology is not mature more work is needed, but a direction seems to be set, and these two towns are to be commended for that.

For the curious, what Landmark and Niverville are doing, is encouraging the growth of swamp vegetation in these lagoons. The plants, as they grow, will extract and accumulate nutrients (also called pollutants), from the water. When the plants are mature, they will be harvested and processed, either to make a fuel or to make compost which can then be applied as a fertilizer on agricultural land.

This floating cattail bioplatform technology is by no means the only technology that could make our participation in the phosphorous cycle more rational and sustainable, but it moves in the right direction. There is more information on this technology here.