Seek­ing san­i­ta­tion for the world’s poor­est

One-third of the world’s pop­u­la­tion is with­out ac­cess to proper toi­lets. To ad­dress this prob­lem, a team from Eawag has de­vel­oped a new kind of la­trine.


“To­day, 6 bil­lion peo­ple world­wide own a mo­bile phone, but only 4.5 bil­lion have de­cent toi­lets.” Kris­tele Malegue, co­or­di­na­tor of the Wa­ter Coali­tion - an NGO that cam­paigns for clean wa­ter — sums up the sit­u­a­tion in one sen­tence: one third of the world’s pop­u­la­tion is with­out ac­cess to proper san­i­tary fa­cil­i­ties, and one bil­lion peo­ple defe­cate in the open. “This short­age, which is still taboo in so­ci­ety, is a real scan­dal. It has se­ri­ous con­se­quences for peo­ple’s health, nutri­tion and ed­u­ca­tion, the econ­omy and the en­vi­ron­ment,” con­tin­ues Kris­tele Malegue. Each year, 1.5 mil­lion chil­dren die from the ef­fects of di­ar­rhoea caused by drink­ing wa­ter con­tam­i­nated with fae­cal mat­ter.”

To ad­dress this prob­lem, Swiss re­searchers from Eawag and the Vi­enna- based de­sign firm EOOS have de­signed a new kind of la­trine, “Blue Di­ver­sion,” as part of the “Rein­vent The Toi­let Chal­lenge ( RTTC)” set by the Bill & Melinda Gates Foun­da­tion. “Flush toi­lets, which are com­monly used in in­dus­tri­al­ized coun­tries, seem to be the ideal so­lu­tion. How­ever, it is dif­fi­cult to in­stall them in de­vel­op­ing coun­tries. In many lo­ca­tions, in­fra­struc­tures such as sew­ers and wa­ter treat­ment plants sim­ply don’t ex­ist, and there is of­ten not enough wa­ter avail­able for flush­ing. Pit la­trines have seen very lit­tle progress over the course of history, and do not meet hy­giene re­quire­ments,” points out Christoph Luthi, pro­ject man­ager at Eawag. “We wanted to de­sign a rad­i­cally dif­fer­ent type of toi­let, with­out the need for hefty in­fra­struc­tures, at the same time as of­fer­ing spot-

less hy­giene.”

‘Elim­i­na­tion of pathogens and

save wa­ter’

To look at, Blue Di­ver­sion re­sem­bles a squat toi­let made out of blue plas­tic, with two holes: one for urine and the other for fe­ces. “The pur­pose of sep­a­rat­ing these is to fa­cil­i­tate the elim­i­na­tion of pathogens and save wa­ter,” ex­plains Christoph Luthi. Through a ni­tri­fi­ca­tion process, the urine is con­verted into fer­til­izer in situ. How­ever, what makes it rad­i­cally dif­fer­ent is the in­te­grated in­de­pen­dent wa­ter cir­cuit. “We have fit­ted our toi­lets with a shower head to clean the pan and also en­sure anal hy­giene, as prac­ticed in a great num­ber of coun­tries, as well as a sink to wash the hands,” con­tin­ues Christoph Luthi. “When­ever the wa­ter flows, a valve au­to­mat­i­cally shuts off the urine and fe­ces tanks. This en­ables al­most all of the liq­uid to be re­cu­per­ated.”

Sub­jected to in­ter­nal bi­o­log­i­cal treat­ment, this dirty wa­ter is dis­in­fected by a grav­ity- driven mem­brane fil­ter. A so­lar-pow­ered elec­trol­y­sis sys­tem then pro­duces chlo­rine, pre­vent­ing un­de­sir­able bac­te­ria from form­ing. “This patented sys­tem is ca­pa­ble of treat­ing 1.5 litres per hour, which is per­fectly ad­e­quate be­cause the ap­pli­ance con­tains 60 liters in to­tal. You can even drink the wa­ter pro­duced, although we don’t rec­om­mend it be­cause you’d then need to re­fill the tank,” con­tin­ues Christoph Luthi. “One to two liters are lost per week, based on nor­mal use.”

Prospects for Fur­ther Ser­vice

In 2013, the first pro­to­type of Blue Di­ver­sion was suc­cess­fully tested in Uganda, work­ing with Mak­erere Univer­sity. “The ap­pli­ance was very well re­ceived by peo­ple dur­ing the tri­als in Kampala,” con­tin­ues Christoph Luthi. “This first trial also al­lowed us to iden­tify cer­tain de­fects. We have since re­duced the height of the toi­let and im­proved the sys­tem’s hy­draulics.” A new pro­to­type is cur­rently be­ing tested in Nairobi, Kenya. Blue Di­ver­sion was awarded the 2014 Prize for In­no­va­tion by the In­ter­na­tional Wa­ter As­so­ci­a­tion (IWA).

“We are now look­ing for in­dus­trial part­ners and in­vestors so that we can pro­duce the units in greater quan­ti­ties,” con­tin­ues Christoph Luthi. “Mass pro­duc­tion will re­duce the cost. The ob­jec­tive is to achieve a selling price of US$500 per ap­pli­ance, for a pro­jected life­time of ten years.”

Is this too ex­pen­sive for the coun­tries in ques­tion? “The lack of toi­let fa­cil­i­ties mainly af­fects SubSa­ha­ran Africa, where just 30% of the pop­u­la­tion has ac­cess to de­cent toi­lets, but it doesn’t stop there. In In­dia, al­most half of the pop­u­la­tion is forced to defe­cate in the open, and even in Europe 20 mil­lion peo­ple are still with­out qual­ity fa­cil­i­ties,” points out Kris­tele Malegue. “One ap­pli­ance won’t ad­dress ev­ery­one’s prob­lems. Dif­fer­ent ap­proaches need to be de­vised to suit the sit­u­a­tion.”

Con­se­quently, Blue Di­ver­sion could come in use­ful in re­mote ar­eas. “The main need is in Africa and In­dia,” con­firms Christoph Luthi, “but we can also see our toi­lets be­ing use­ful else­where, par­tic­u­larly in moun­tain huts and re­mote vil­lages, which will never be con­nected to the waste wa­ter san­i­ta­tion net­work. What’s more, some coun­tries are also in­ter­ested in the wa­ter pu­rifi­ca­tion sys­tem we have de­vel­oped, with­out the toi­lets, be­cause it pro­duces drink­ing wa­ter.”

Mean­while, the re­searchers are cur­rently look­ing into what can be done with the fe­ces. “At the mo­ment, our sys­tem only con­verts the urine into fer­til­izer. The ac­tual stools have to be dis­posed of, which poses a prob­lem due to the pathogens they con­tain,” ex­plains Christoph Luthi. “We are work­ing on a sys­tem to burn this solid residue which, I hope, will be op­er­a­tional by the end of 2015.”


Do­minic Buttner/LUNAX

The “Blue Di­ver­sion,” a toi­let model that pro­vides low-tech so­lu­tions to hy­gienic prob­lems, is seen in this pic­ture.

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