4 Out of 5 Like Toilet That Separates No. 1 from No. 2

Adam Hadhazy

Date: 12 March 2010 Time: 04:33 AM ET

A typical NoMix toilet, which is gaining popularity in Europe for its green credibility.
CREDIT: Yvonne Lehnhard

An environmentally friendly toilet that collects urine and feces separately gets good reviews from those who use it.

Known as NoMix toilets, the green-minded commodes essentially have built-in urinals. A raised area in the front of the bowl that drains urine into a different tank, while poop gets deposited in the back half of the bowl to flush away as normal.

NoMix toilets began catching on in Sweden about a decade ago and have made some inroads in lavatories in north and central Europe, especially in planned "eco" communities.

"Separating waste streams and dealing with waste at its source should be possible and makes more sense in a technological society," said Judit Lienert, a researcher at the Swiss Federal Institute of Aquatic Science and Technology (Eawag) and lead author of the new paper.

Conventional plumbing is, well, awfully conventional, Lienert points out.

"What we’re doing now was invented by the Romans," she said.

To get a sense of how bathroom-goers feel about these new-fangled toilets and their Earth-friendly benefits, two researchers Eawag pulled together surveys from 38 NoMix pilot projects and studies in seven European countries.

In total, of some 2,700 respondents, four out of five liked the idea of NoMix technology and were satisfied with the design, hygienic aspects, smell and the all-important seating comfort of these toilets.

Got to keep 'em separated

The splitting of where urine and feces go offers many advantages, the study explains.

In the developed world, sewers are used to pipe feces and urine to wastewater treatment centers, but this model is expensive and ultimately unsustainable, Lienert said.

"One solution that is far easier than sewers and wastewater treatment is just to take out the urine and reuse it," she told TechNewsDaily.

Urine contains nutrients such as nitrogen and phosphorus, so it works well as a fertilizer.

Survey respondents overwhelmingly favored such an application of urine and said they would purchase food grown with it. Recycling urine this way also saves water that would otherwise be used to flush urine away.

Better to have pee end up in the garden or on the farm rather than in rivers and seas, Lienert said, where it feeds algae. These small aquatic life forms can grow out of control in so-called algal blooms, consuming much of the oxygen in the water, killing off fish and other marine species.

Toilet troubles

NoMix toilets do have some disadvantages, however, as revealed by the survey.

The majority of people thought the NoMix toilet's flushing capabilities did not equal that of conventional toilets, and cleaning them was harder as well.

Using a NoMix toilet also requires a change in restroom rituals, such as extra steps to manually withdraw the collected urine if it is to be used as local fertilizer.

Experimental concepts for disposing of urine using existing sewer lines include storing the urine and then sending it to a treatment plant during the night. Because other excretory traffic is low at these hours, feces and urine would remain separate and easier to treat on their own.

But the biggest barrier to NoMix toilet adoption might be psychological, however. To best "target" the separate urine collection area, many men – long used to relieving themselves from a standing position – will have to take a seat on NoMix toilets.

If these barriers can be overcome, humanity will move forward into a more environmentally sound future, one toilet at a time, Lienert said.

The research was reported in the January issue of the American Chemical Society's Environmental Science & Technology journal.