Wastewater or energy source?

Posted Wednesday, February 20, 2013 in Sustainable Maine

Wastewater or energy source?

Image Source: Wikipedia Commons

by Paul Kando

The warmer the planet, the more water evaporates, creating drought here, deluge or intense storm there. The warming also impacts fresh water supplies. Saline oceans cover approximately 70 percent of the Earth's surface. Fresh water is stored in shrinking polar ice fields and mountain glaciers that feed our rivers. Less than one percent is accessible from lakes, streams and aquifers for soon-to-be nine billion people’s domestic, commercial, agricultural, industrial, and environmental needs. Stable for centuries, a warming Earth’s fresh water supplies are stressed, as glaciers and snow-pack melt and lakes lose water through premature storm runoff and evaporation. In the U.S. there have been recent water shortages in nearly every region, even as water use has been increasing. Atlanta and Las Vegas almost ran out of water. Low water levels on the upper Mississippi threaten barge traffic. The Colorado’s water seldom reaches Mexico.  According to government reports, at least 36 states – three-fourths of the country – can expect water shortages this year, even under non-drought conditions.

Maine is not among the 36, so why should we care? Because, among other things, water problems where food is grown, and barge traffic restrictions that jeopardize economical commodities shipments, affect us all.

American homes consume more than half of publicly supplied water. A family of four consumes up to 400 gallons daily, 160 of that to flush toilets, a convenience we take for granted. Yet isn’t it wasteful to mix potable water, human manure, urine, and grey water from kitchen, laundry and bath? This effluent also includes medicines and household chemicals. It winds up in municipal water treatment plants, which -- at great expense, much of it for energy – reclaim some of the water. Alternatively the mixture flushes into private septic systems whose sludge gets dumped somewhere on the ground. No wonder that a 2008 Associated Press study found traces of prescription drugs, -- sex hormones, mood stabilizers, antibiotics and more -- in the drinking water supply of 41 million Americans.

Flush toilets were first used in the Indus Valley cities of Harappa and Mohenjo-daro in 26th century B.C.E. Today’s versions and the modern sewage system date to 19th century England. They hugely improved hygiene and public health. Still, rethinking our use of water as a carrier of waste may now be in order. For starters, manure, including human manure, is not waste but an asset. Decomposing in the absence of air it produces methane, the key ingredient in natural gas, leaving a residue suitable as a fertilizer. Methane digesters are simple and inexpensive. Yet we routinely waste this energy source in our ill-conceived treatment of water-as-waste, not to mention the drug-contaminated, stinky manure-lagoons externalized by industrialized animal feedlots. Feedlot manure is unsuitable as a fertilizer, so we manufacture artificial fertilizers -- from a fossil fuel, no less -- that leach into waterways, causing algal blooms and ocean dead zones. We waste more energy in fertilizer manufacture, pumping clean well water only to contaminate it, pumping and treating sewage, agitating huge evaporative ponds, etc. And, by failing to harvest it, we permit methane, a far more potent greenhouse gas than carbon dioxide, to escape from landfills and manure pools into the atmosphere. Can’t we do better?

Some do. Modern Swedish toilets collect feces and urine separately, treating each as a resource. Vancouver, B.C. heats 26,000 homes using sewage-derived methane. A Seattle school uses vacuum-powered composting toilets. Several public buildings in Maine use waterless urinals. A Norwegian company markets a composting toilet that produces methane for cooking. Chinese and Indian farmers have, for decades, used simple methane digesters that convert manure and farm waste to cooking gas and fertilizer. Many German cities and villages produce their own biogas from sewage and organic household waste, for heating, transportation and power generation. Some Swedish trains have been running on biogas for years. (Burning methane instead of emitting it reduces carbon emissions by about 96 percent.)

My neighbors and I still mix our “wastes” with pure drinking water. Our water treatment plant works round the clock to separate those ingredients, even as we mix more together. An estimated one-third of the solid waste we dispose of at the transfer station is methane-digestible organic waste, yet we pay over $90 per ton to have it trucked away -- yet we bemoan our local taxes. How does all this make sense? 

Well, it does for those who think “economics” means managing money. The Gross Domestic Product (GDP) counts money spent, no matter how foolishly, as “contributing to growth” --  the cost of everything mentioned above, cleaning up after Superstorm Sandy, treating its injured, burying its dead, even the price paid for the exploded natural gas that burned to the ground Breezy Point, Long Island. How real is such “growth” while the real economy is tanking?

We can explain how our conventional systems came to be, but how does that justify failing to update them in light of new information? Wasting clean water and energy? Avoidably burdening the environment with carbon, nitrogen and toxins? How about self-financing waste management?  Running our school buses on reclaimed methane? Creating some good local jobs?

Rethinking how we use water and produce our energy, might even reduce our local taxes.

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