Most would agree that the waste in municipal wastewater isn’t just the human waste but the vast amounts of fresh, clean water going right down the drain, as well as the spent energy to collect fresh water, treat it to drinkable standards, transport it to facilities for use, transport it after use to different facilities for treatment, and then discharge it. Whew.
We’ve covered wastewater reuse in CE News before — a growing trend and one that advanced treatment and filtering technologies are helping to make more affordable. But the truth is, even if you reuse the water, you’ve still used a lot of energy and water throughout the process. We’ve also reported on facilities that capture rainwater to use for toilets and other uses such as irrigation, decreasing the drain on the public water supply, minimizing costs for owners, and just making good sense. But there is another angle to take when considering conservation and wastewater management and treatment issues, one we haven’t covered before that could impact civil engineers in the future.
Significant efforts have been made to make toilets more efficient, since they account for 30 percent of an average home’s indoor water consumption, according to the U.S. Environmental Protection Agency (EPA). Different types of low-flow toilets, such as large drain passages, redesigned bowls and tanks for easier wash down, and others that supplement the gravity system with water supply line pressure, compressed air, or a vacuum pump, are making strides to diminish the excess water used. And requirements and government-labeling programs are helping to conserve water in toilets.
Today, toilets must adhere to the requirements of the National Energy Policy Act, which mandates that they use no more than 1.6 gallons of water per flush. Standard toilets use 3.5 gallons per flush, and according to the EPA’s WaterSense website, “Replacing these toilets with WaterSense labeled toilets could save nearly 2 billion gallons per day across the country — that’s nearly 11 gallons per toilet in your home every day!” (WaterSense is the EPA’s water-saving program, similar to the well-known ENERGY STAR energy-saving program.) While it is unlikely that most families will replace their functional toilets, these commodes are great options for new construction and are being used for residential and commercial buildings as well. But they aren’t the only choice.
Turns out that composting toilets, most commonly installed in parks and roadside facilities, are gaining more acceptance. For example, the C.K. Choi Building at The University of British Columbia in Vancouver is a 30,000-square-foot office complex that uses composting toilets and urinals for human waste disposal. Also, this past summer, the Austin, Texas Water Utility approved a composting toilet facility on a multi-acre site owned by the Rhizome Collective, where the non-profit center displays functioning ecological tools and technologies for sustainable urban living. (To see a video, go to http://tinyurl.com/CEvideo.)
So how does this affect civil engineers? What I’ve been thinking about is that even with projected population increases, more efficient toilets means less wastewater. And that could spell trouble for civil engineering businesses and professionals who make their living helping to collect, transport, treat, and manage this possibly diminishing substance. Further, all of this makes me wonder if the reason we hear so much more about wastewater reuse and recycling (and very little about civil engineers’ involvement in reduced consumption) is because these processes keep civil engineers working, rather than highly efficient options that could negatively impact the business of civil engineering.
Shanon Fauerbach, P.E.,