Coho and Climate Change

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The Wisconsin weather is finally getting warmer and so begins the best time to enjoy my favorite outdoor activities ‒ golf and fishing. This past week I had the pleasure of both, including a successful expedition on Lake Michigan to catch Coho salmon.


Lake Michigan in Racine, WI May 23, 2015

Just as we were planning another trip for the weekend, we were reminded of how volatile spring weather can be. High winds are in the forecast, making it hazardous to fish Lake Michigan. The volatility of spring weather was even more evident this week in Texas when severe rains led to devastating flooding. Obviously, spring is the most unpredictable weather of the year but one has to wonder if climate change is making things worse.

Discussing climate change is a challenge for me because as a scientist I rely on facts and a strong technical foundation to form my position. On the one hand, the CO2 level in the atmosphere is the highest in centuries. At 400 ppm, it is about double the level of a couple hundred years ago.

On the other hand, consider what fraction the CO2 of the atmosphere represents.


Composition of Earth’s Atmosphere

The controversy about climate change usually revolves around one of three things – whether this small component of the atmosphere is to blame for extreme weather (drought, floods and warmer temperatures), whether the increase in carbon dioxide is anthropogenic (man-made), and if we should do anything about it.

I feel pretty confident making the following statement: our infrastructure should be designed for resilience against nature’s impacts, whether it’s rising sea levels or flooding from heavy rains. Engineers must model future weather events to properly design for such incidents and it is prudent to consider how climate change may impact the models. However, modeling uncertainty makes it difficult to design resilient infrastructure that is also fiscally responsible. And so debates ensue whether climate change is real or imagined and whether we should do anything about it.

To me, the best approach consists of simple steps that make good sense for additional reasons beyond climate change. An example is the diversion of organics from landfills and promoting the use of biogas instead of fossil fuels. This practice not only reduces greenhouse gas emissions but also provides economic benefits at the same time. Along that line of thinking – the Coho were outstanding made on the grill; the secondary benefit of a fun day on the lake.


Land of the Lost Resources

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This month I stayed on Hayden Island in Portland, OR for this year’s BioCycle West Coast Conference. We were somewhat isolated, and I heard a municipal official say something to the tune of, “We’re looking for options other than losing resources down the sewer.” In more ways than one I felt in the “Land of the Lost” – the show I watched as a kid and later made into a comedy with Will Ferrell. It seems, at least to some people, that sending food waste through a disposer and household plumbing to the water resource reclamation plant is somehow considered lost.

The notion that mixing food waste with wastewater results in lost resources comes from the supposition that only food waste is a resource, while wastewater on the other hand is waste. I am reminded that long ago I learned that wastewater is 99% pure water. That’s right only 1% is the nasty stuff. (This, incidentally, is the same claim made by Ivory soap years ago in their advertising.)

There is the claim that to recapture the food waste “resource,” the mixed food waste and sewage must be separated at the treatment plant. Wastewater treatment does just that through physical and biological processes – physical being sedimentation and biological being secondary aeration.

So I submit that sending food waste through sewers to the treatment plant does not mean it’s lost. Far from it. In fact, treatment plants make the most of all the embedded resources in ways composting cannot.

First, food waste is 70-90% water, so water is the end product of wastewater treatment. Second, biosolids can be used as a soil amendment and fertilizer, just like compost. Third, energy can be generated from food waste through anaerobic digestion to process sludge into reusable biosolids.

Although wastewater treatment is the greatest contribution to human health on this planet, there is a stigma about these facilities, even among those who you’d think would know better.