No one ever said sewage would be sexy Sean Tynan
Going green has made even waste treatment glamorous. Solid waste management is a hot topic. Recycling has gained fairly broad acceptance, composting is back in the limelight, and plastic grocery bags have become pariah. When I started my co-op job with the Province of British Columbia, I was hoping that liquid waste (sewage) would follow suit.
We haven’t changed the way we manage our waste in over fifty years. Basic practices in waste management should not be overlooked, no matter how wealthy your country is. Just look at Dubai, home to a plethora of celebrities and beach resort for Europe’s uber-rich, which recently closed its most prestigious beach when schools of “wild brown trout” began washing up on their beach. The “ick” factor, however, is not the key reason we should be treating our waste. In these excitingly green times, where idealistic (and occasionally delusional) young thinkers like yourselves are designing landscapes, buildings, bridges, and cities founded on solid ecological foundations and design-with-nature approaches, it seems about time that our most basic infrastructure followed suit.
As any ecologist will tell you, there is no such thing as waste in nature. Everything is energy (food) for something else. Elemental nutrients (nitrogen and phosphorous, for example) are required as an input in all farming practices. We cannot, and I repeat, cannot create or destroy elements. But we can make them unavailable for human use, such as when we dispose of sewage into the ocean.
Enter the glamorous world of Integrated Resource Recovery. This is a byword for projects which treat “waste” (an outmoded concept at best) as something of value, and places it within the management paradigm of other resources. This is one step in “closing the loop”.
It seems that there are a lot of “silent crises” these days going on around the world. There is, by the way, one for fertilizers as well. Major shortages of these nutrients are being caused by increasing demand and decreasing supply. The latter largely because a majority of the world’s cities disposing of nutrients the old-fashioned way: out to sea. This has more of an effect on food prices than most other factors, and fertilizer prices are increasing faster than the cost of fuel.
With each grand flush, we are wasting a valuable commodity. Ecology aside, this stuff is worth big bucks. A variety of technologies exist to capture value from human waste, which would allow us to reduce the life-cycle cost of sewage treatment infrastructure, and in some cases even earn revenue for cities from it. A few of these are described below.
Sewage-heat recovery is a fairly novel technology in North America. Okanagan College in Kelowna, and more recently the Olympic villages in Whistler and Vancouver, showcase three different commercially viable technologies for recovering heat. The CRD project will likely feature something of this nature.
A rich source of heat is provided by sewage treatment plants, as the microbes which decompose our waste raise the temperature.
Heat pumps are the keystone which allows us to concentrate this heat. I won’t go into the technical details here, but think refrigerators, which use electricity to concentrate heat outside the fridge, making it colder inside. Reverse that process, and you understand heat pumps.
Anaerobic digestion is the process of capturing methane from the decomposition process, and can be used with anything from kitchen waste in small backyard digesters, to animal and human waste. This is considered a carbon neutral fuel and can be upgraded to natural gas. While I would prefer not to use it at my next barbeque, natural gas from human waste is an effective and efficient use of energy, and will become increasingly viable as fuel prices rise.
Nutrient recovery is already practiced at a large number of sewage treatment plants. I’ll be blunt: much of the food you have consumed in your life has been grown with human fertilizer in the mix. The term here is “class A biosolids” which sounds much nicer. To my way of thinking, this is probably the most important form or resource recovery to accomplish, as we simply cannot make more fertilizer as we run out.
Systems which take advantage of these technologies exist in Sweden, Denmark, and the Netherlands, among other place. So why aren’t we doing this already? A variety of barriers crop up, ranging from political will, bureaucratic momentum and fragmented governance structure to flawed accounting and market failure.
There is no better opportunity than now. Much of the infrastructure in BC is in need of replacement and upgrade, and the liquid waste management plans in Metro Vancouver and the Capital Region District (Victoria) are being decided on as we speak.
And this is really the crux of environmental sustainability: the willingness to mimic or recreate natural processes, such as nutrient cycling, within our society. If we can’t be sold on this, the whole idea of sustainability is just a big pile of...
