Love that dirty water: Scientists find low-tech way to recycle H2O

May 24, 2010 By Tom Avril

Horticulturists at Pennsylvania State University have come up with a low-cost, green method for recycling so-called "gray" water -- the stuff from sinks, showers and washing machines that would otherwise go down the drain.

They filter the water through some and layers of crushed stone, peat moss and -- making it clean enough to reuse for growing vegetables or flushing toilets -- but not for drinking.

Using gray water is generally not allowed in the United States, but some states have explored the idea. The Penn State researchers hope their data -- which show such biofilters can remove almost all suspended solids, nitrogen compounds and other pollutants from gray water -- might lead to greater acceptance.

Meanwhile, such filters could be used in poor nations that lack adequate water for sanitation and irrigation, said Robert D. Berghage, associate professor of horticulture.

Robert Cameron, the doctoral student on the project, presented the research this month at a sustainable-farming meeting in Cuba.

The system consists of two plastic pipes filled with layers of porous rocks, soil, crumbs from discarded tires, composted cow manure and peat moss. Vegetables and other plants are planted in holes along the sides of the pipes.

The pipes stand in a basin with still more plants -- papyrus and horsetail reed -- whose roots support microbes that remove pollutants.

Each material in the pipes removes different contaminants, though the tire crumbs are there mainly as filler. Tire crumbs also contain contaminants, but tests showed they are not released into the water, Berghage says.

With enough treatment, you could even drink water that goes through such filters, Berghage says. He admits that this wouldn't gain wide acceptance, even though drinking-water plants already treat from rivers that receive treated waste.

"Most of us have this sort of aversion to drinking treated wastewater," he says, "even though much of the time we're doing it anyway."

Explore further: Roots meshed in waste materials could clean dirty water


Related Stories

Roots meshed in waste materials could clean dirty water

May 5, 2010

Plant roots enmeshed in layers of discarded materials inside upright pipes can purify dirty water from a washing machine, making it fit for growing vegetables and flushing toilets, according to Penn State horticulturists.

Lead leaching and faucet corrosion in PVC home plumbing

June 2, 2008

Scientists in Virginia are reporting that home plumbing systems constructed with polyvinyl chloride (PVC) plastic pipes may be more susceptible to leaching of lead and copper into drinking water than other types of piping ...

What's in our water?

November 5, 2009

( -- Although America's supply of drinking water is considered among the world's safest, there is an urgent need to develop more stringent regulations to guide how water is monitored for pollutants, according ...

Human waste feeds rest stop greenhouse

August 31, 2005

A new Vermont highway rest stop has blue water in the toilets as part of a "green" system that uses tropical plants to cleanse and recycle sewage water.

Scrap tires can be used to filter wastewater

November 17, 2006

Every year, the United State produces millions of scrap tires that clog landfills and become breeding areas for pests. Finding adequate uses for castoff tires is a continuing challenge and illegal dumping has become a serious ...

Recommended for you

Mystery solved for mega-avalanches in Tibet

January 23, 2018

An international scientific effort determined the cause of a highly unusual and deadly glacier avalanche in Tibet in 2016, a new Nature Geoscience paper says.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (2) May 25, 2010
They filter the water through some plant roots and layers of crushed stone, peat moss and waste materials -- making it clean enough to reuse for growing vegetables or flushing toilets -- but not for drinking"

Oh, for heaven's sake. Septic tanks and drain fields have been doing this for centuries.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.