Biological Graywater System Pre-Treats with Plants and Clay Balls

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Biological Graywater System Pre-Treats with Plants and Clay Balls

The innovative system purifies household water to the point where mechanical filters don't have to work as hard.
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Biological #Graywater System Pre-Treats with Plants and Clay Balls by @MattPGBM

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Friday, September 16, 2016 - 12:00pm

CAMPAIGN: Saving Water


Research underway at Hunt Utilities Group (HUG) in Pine River, MN, is demonstrating the benefits of natural treatment of graywater. The system, installed in the home of Paul Hunt, founder of HUG and its headquarters, The Resilient Living Campus in Pine River, MN,—shows what's possible if a passive solar space is dedicated completely to graywater management.

Water from showers and sinks is processed through a 9-ft. tall array of plant-filled trays, which contain only expanding clay balls such as those used in aquaculture. The key, of course is to select water-loving plants that require no soil nutrients for growth.

"The system works very well," notes Dan Pavek, "We did find that in the winter we have to add a little mechanical light to keep the plants healthy."

The system is designed to work optimally with about 4 hours of sunlight, he says,a bit more than the long Minnesota winter days can guarantee.

One of the spinoffs from this approach is HUG's current effort to come up with a compact version of the graywater system for use in tiny homes. The tiny house version will incorporate plants in louver-type containers around the top of the bathroom space.

This is in keeping with Ryan Hunt's plan. Chief researcher and son of Paul Hunt, he hopes to add off-grid capabilities to tiny living. He's also working on a new type of composting toilet that could travel with a tiny house. He and Pavek have built a pavek in the loft area of their warehouse-like research building. They're also testing other tiny house systems.

I asked Pavek about the challenge of what to do with graywater once it has been partially cleaned by plants. Reverse osmosis filtration, I've been told, takes a powerful pump to push the water through the filter membrane. "That's one of the good things about this," Pavek explains. "The water is cleaner, so it takes a lot less pressure to filter it."

To date, the mini-version of the system has not been tested, but the prototype is mostly built. Pavek says the problem is that "water is a fickle beast," and is finding a way to leak from the assembly, despite their best efforts so far. He's confident the fix is right around the corner.

"I'd like all of my kids to head off to college with a tiny house in tow," notes Ryan Hunt. "But there's the problem of water and sewage disposal that require infrastructure. We're trying to change that, so that tiny houses can be used anywhere."

Hunt Utilities Group Website

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