URL: http://innovations.coe.berkeley.edu/vol7-issue1-feb13/loo.html

Humanitarian Engineering for Development Workers ERE 496 student Deanna Kreinheder discusses solutions to help reach Millennium Development Goals (MDG) 4 and 7

The news article “A new loo” written by Julianna Fleming is found in Berkeley Engineering’s February 2013 issue of Innovations.  It explores a new sanitation technology invented by Kara Nelson and Temitope Ogunyoku that turns human waste into “safe sludge”, the pHree Loo.  The mixture of urine and feces creates ammonia which becomes a disinfectant as the pH increases with the addition of lime.

The article opens with the compelling statistic that nearly forty percent of the world’s population do not have access to modern toilets.  A joint monitoring program by UNICEF and World Health Organization (WHO) reported that some 2.5 billion people lack adequate sanitation amenities and hundreds-of-millions do not have access to safe drinking water.  These occurrences are not unrelated as poor sanitation often leads to water contamination.

The contamination of drinking water is often dealt with by disinfecting the water but as long as there are humans needing drinking water, there will be human excrement as a possible source of contamination.  Pit latrines fill-up eventually and only so much land can be dedicated to new sites, what happens to the excrement then?  Despite its general reputation, the only real issue with excrement is any harmful pathogens it harbors.  It would seem more efficient then to disinfect the waste before it gets into the environment, no matter what its destination.  Whether the safe sludge ends up in agricultural fields or thrown in an open lot, it’s better than the untreated sludge that still ends up there in this imperfect and real world.

The prototype seemed to be made almost entirely of plastic with PVC piping for the hand cranked mixing mechanism.  The intention is that the disinfected solution will go to a processing facility.  While this extension of the design could be costly, the fundamental technology is not.  Labor requirements are minimal and although the moving parts may elicit maintenance, parts should be cheap, readily found and simple to repair.  The design does not seem as if it would conflict with cultural practices, however, specific problems may arise which would warrant modifications to be made.

Sustainable treatment of human excrement can have a positive impact on the MDGs both directly and indirectly.  It can decrease contamination of drinking water thereby increasing access to safe drinking and decreasing water-transmitted disease.  If waste can successfully and sustainably be turned into a resource, it will be a win-win.

Vinneras et. al. (2003) studied the addition of urea to fecal matter as a form of disinfection.  They found that ammonia was produced in addition to an increase in pH.  They concluded that urine was an adequate disinfector reducing incidence of E. coli and Salmonella.

A group of engineers including Karl Linden created another toilet that would disinfect human feces.  Their design, Sol-Char, uses concentrated solar power to burn feces thereby disinfecting it and creating a byproduct called biochar.  The biochar has the advantage that it can probably be applied directly for agricultural purposes.  While this solution also turns human waste into a resource while removing pathogens from the environment, it is a more demanding design.  At this point it is not ready for application it is still very large and expensive.  It requires solar radiation to pass through cables and therefore it is more likely to have issues with safety, additional cost, maintenance, and labor.  As of now the pHree loo is a more appropriate technology to address MDGs 4 and 7 in the developing world.


pHree loo

pHree loo







Fleming, Julianna. “A new loo.” Innovations. Berkeley Engineering, Feb. 2013. Web. 28 Apr. 2014. <http://innovations.coe.berkeley.edu/vol7-issue1-feb13/loo.html&gt;.


“Introduction.” Water, Sanitation and Hygiene. unicef, n.d. Web. 28 Apr. 2014. <http://www.unicef.org/wash/&gt;.


Mead, Derek. “This Solar-Powered Toilet Torches Poop for Public Health.” Motherboard. N.p., 14 Mar. 2014. Web. 28 Apr. 2014. <http://motherboard.vice.com/read/this-fiber-optic-toilet-burns-poop-with-the-power-of-the-sun&gt;.


Vinneras, B, A Holmqvist, E Bagge, A Albihn, and H Jonsson. “The potential for disinfection of separated faecal matter by urea and by peracetic acid for hygienic nutrient recycling.” Bioresource Technology 89.2 (2003): 155-61. Web. 28 Apr. 2014. <http://www.sciencedirect.com/science/article/pii/S0960852403000440&gt;.