Published on December 7th, 2013 | by Tina Casey0
Meet A Nifty Little Green Sewage Treatment Plant
December 7th, 2013 by Tina Casey
We haven’t touched base with the whole constructed wetlands thing recently, but we caught a glimpse of this drop-dead gorgeous example of the practice during a tech tour of Israel and that motivated us to check out the latest news about natural sewage (okay, so wastewater) treatment here in the U.S.
In contrast to the whizz bang high tech stuff we usually cover, constructed wetlands are just that: engineered swamps where naturally occurring microorganisms digest the organic material in municipal wastewater, pulling out harmful substances as well as cutting down on the nutrient load.
The same process occurs in conventional treatment plants, only a conventional plant revs it up to the max with precisely regulated environments called digesters. The problem with that approach is twofold: first, compared to constructed wetlands the conventional infrastructure is far more expensive to build, and second, conventional plants are far more expensive to run, partly because of their tremendous thirst for energy.
For many cities, conventional treatment is the only way to go due to considerations of space and volume, but in a growing number of areas the attraction of huge savings on construction and operating costs is pushing the trend toward constructed wetlands.
Constructed Wetlands For A Carbon Neutral Neighborhood
Before we take a look at some US examples, let’s wander back over to Israel for a moment. We had a chance to visit Kibbutz Lotan in the arid Arava region on that aforementioned tech tour (sponsored by the Israeli organization Kinetis). Lotan is the home of the Center for Creative Ecology, which focuses on low-tech, high efficiency building solutions, recycling, solar power and other pathways to achieving a carbon neutral neighborhood when money is in short supply but local materials such as biomass, clay, and reclaimed trash are abundant.
The relatively small constructed wetland pictured in this post is scaled to need, which is minimal in this instance because it serves a public restroom at Lotan that uses another up-and-coming low tech solution, composting toilets. Solid material is separated out for composting, so only liquid waste is shunted to the constructed wetland.
We previously covered some of the high tech solar power solutions under way elsewhere in Arava, which are being designed with an eye toward beating diesel in the race to bring electricity to developing economies around the world. The constructed wetland and other demonstration and research projects carried out at Lotan complement those solar projects, by offering communities in arid regions a low-cost pathway for getting the most out of a PV installation.
Lotan’s own solar plant, though modestly scaled, provides enough daytime electricity to run its extensive grounds and keep its interior spaces cool. It also doubles as a shade roof over the kibbutz’s open air recycling center.
Constructed Wetlands In The USA
One of our favorite examples of a constructed wetland is the “Living Machine” designed by Worrell Water Technologies for the Otay Mesa Land Port of Entry in California. At this busy border crossing, visitors get their first taste of the US by strolling along a path that meanders through a beautifully landscaped area, little suspecting that it doubles as a natural wastewater treatment plant.
Last time we checked, Worrell was also constructing a managed wetland inside of an office building (yes, these things work indoors, too).
A good example of the potential for savings is the new wetland in Washington, Indiana, which has won several awards, including last spring’s Engineering Excellence Honor Award from the American Council of Engineering Companies.
As reported by the Washington Times-Herald, the project addressed storm-related sewer overflows, which had turned a natural waterway called Hawkins Creek into a public health hazard incapable of supporting wildlife.
Upgrading the local treatment plant would have cost $54 million, a heavy burden for this relatively small community.
The constructed wetland, designed by the firm Bernardin Lochmueller & Associates, costs $26 million less to build and involves a $1.6 million savings in annual operating costs.
The heart of the system is a 27-acre constructed wetland that includes a forebay for settling out solids, as well as a disinfection facility ahead of the discharge into Hawkins Creek.
The result, as reported by the Times-Herald:
Water quality tests showed that the water being discharged by the wetland system surpassed IDEM’s [Indiana Department of Environmental Management] quality requirements and even surpassed the more stringent standards for the city’s wastewater treatment plant. For the first time in years, Hawkins Creek has minnows, frogs, and other wildlife.
Another good example comes from the upscale world of private golf clubs, where the St. Andrews Country Club of Boca Raton, Florida has reached over to the local wastewater treatment plant for help in tending its greens and other areas.
The club doesn’t generate enough reclaimed wastewater on its own, so it’s piping in treated wastewater from the Palm Beach County Utilities facility, which uses a 50-acre wetland as part of its treatment system.
So, let’s hear it for constructed wetlands.
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