Sanitation of faeces from source-separating dry toilets using urea.
OBJECTIVE
To develop a reliable and simple method to produce safe fertilizers from human excreta using urea for sanitation of faeces.


RESULTS
Urea was added to faecal matter (17% dry matter) at concentrations of 0.5-2% (w/w) and inactivation of Salmonella enterica subspecies 1 serovar Typhimurium (Salm. Typhimurium), Enterococcus spp. and the Salm. Typhimurium bacteriophage 28B was monitored at 14, 24 and 34 degrees C. Urea additions enhanced inactivation and inactivation rates were positively related to increasing NH(3) (aq) concentration and temperature. Salm. Typhimurium was the most sensitive of the organisms studied, while Enterococcus spp. showed more persistence, especially at lower temperatures. The bacteriophage was the most resistant organism studied.


CONCLUSIONS
Salmonella reduction levels that meet requirements for safe reuse of faeces as fertilizer (i.e. 6 log(10) reduction) can be achieved for 1% urea within 2 months at 14 degrees C or within 1 week at 24 degrees C and 34 degrees C.


CONCLUSIONS
The relationships between organism inactivation rates and temperature, ammonia and pH were identified. Urea treatment proved to be a robust and efficient option for safe recycling of plant nutrients.
Nordin
A
A
Department of Energy and Technology, Swedish University of Agricultural Sciences, Uppsala, Sweden. annika.nordin@et.slu.se
Ottoson
J R
JR
Vinnerås
B
B
D000641:Ammonia / Q000378:metabolism; D004203:Disinfection; D016983:Enterococcus / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D005243:Feces / Q000382:microbiology*; D006801:Humans; D012475:Salmonella / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D012483:Salmonella Phages / Q000254:growth & development / Q000502:physiology*; D013696:Temperature; D014508:Urea / Q000494:pharmacology*
D000641:Ammonia; D014508:Urea