Inactivation of Ascaris eggs in source-separated urine and feces by ammonia at ambient temperatures.
Sustainable management of toilet waste must prevent disease transmission but allow reuse of plant nutrients. Inactivation of uterus-derived Ascaris suum eggs was studied in relation to ammonia in source-separated urine without additives and in human feces to which urea had been added, in order to evaluate ammonia-based sanitation for production of safe fertilizers from human excreta. Urine was used concentrated or diluted 1:1 and 1:3 with tap water at 4, 14, 24, and 34 degrees C. Fecal material, with and without ash, was treated with 1% or 2% (wt/wt) urea at 24 and 34 degrees C. At 34 degrees C eggs were inactivated in less than 10 days in urine and in amended feces. At 24 degrees C only feces with 2% (wt/wt) urea or 1% (wt/wt) urea at high pH (10) inactivated all eggs within 1 month, and no inactivation was observed after 75 days in urine diluted 1:3 (18 +/- 11 mM NH(3)). At temperatures of > or =24 degrees C, NH(3) proved to be an efficient sanitizing agent in urine and feces at concentrations of > or =60 mM. Treating fecal material at 34 degrees C can give a 6-log(10) egg inactivation within 1 month, whereas at 24 degrees C 6 months of treatment is necessary for the same level of egg inactivation. At temperatures of 14 degrees C and below, inactivation rates were low, with viable eggs after 6 months even in concentrated urine.
Nordin
Annika
A
Swedish University of Agricultural Sciences, Department of Energy and Technology, Uppsala, Sweden. annika.nordin@et.slu.se
Nyberg
Karin
K
Vinnerås
Björn
B
D000641:Ammonia / Q000494:pharmacology*; D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D017165:Ascaris suum / Q000187:drug effects*; D005243:Feces / Q000469:parasitology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D012499:Sanitation / Q000379:methods*; D016019:Survival Analysis; D013696:Temperature; D013997:Time Factors; D014508:Urea / Q000494:pharmacology; D014556:Urine / Q000469:parasitology*
D000871:Anthelmintics; D000641:Ammonia; D014508:Urea