The use
in agriculture of excreta from urine-diversion toilets can be an alternative
solution to the lack of sanitation and high costs of mineral fertilizers
inherent to developing countries. The objective of this study was to evaluate
the hygienic quality of urine used as fertilizer through an ecological
sanitation system in Ouagadougou peri-urban areas. Chemical and microbiological
analyses were performed in urine samples taken before and after thirty (30)
days of storage in jerry cans exposed to sunlight. The concentrations of 7.0
g/l; 3.5 and 9.6 g/l of ammonia nitrogen for mean, minimum and maximum
respectively, are obtained in unstored urine samples. These concentrations did
not practically vary with the storage. On average, values of other chemical
parameters analyzed in stored urine were as follows: pH, 8.8; phosphorus (P),
0.3 g/l; potassium (K), 1.9 g/l; total dissolved solids (TDS), 21.0 g/l;
cadmium (Cd), 154.3 μg/l; copper (Cu), 5.2 μg/l; lead (Pb), 15.2 μg/l; chromium
(Cr), 6.1 μg/l; nickel (Ni), 154.0 μg/l. Escherichia
coli, staphylococci, enterococci, Salmonella and spores of Clostridium perfringens were detected in unstored urine samples, with 26% of fecal contamination rate.
The time of storage (30 days) under sunlight was enough for almost all bacteria
removal in urine samples. Although the fertilizing value of urine was
confirmed, it would be important to take account of the best practices on
applying in soils, because of the high TDS contents. Also, the risk linked to
micropollutants in urine-based fertilizers could be negligible in view of low
quantities. The results obtained in this study prove that after 30 days of
exposure to sunlight urine collected via eco-toilet becomes bacteriologically
sanitized, and can therefore be used to fertilize soils. However, it is
necessary to demonstrate the inactivation of other groups of enteric
microorganisms in human urine during storage.