Hygienic quality of human excreta in the storage options in Vietnam Background The use of human excreta in agriculture presents potential health risks if excreta are not properly treated before using as fertilizer. In Vietnam, farmers traditionally store and compost excreta before fertilizing crops. However, the level of safety of the current storage and composting options for health and environment are not scientifically examined. Optimizing excreta storage options to ensure the safety of their use is of great importance for public health and the environment. Aims This study aimed to investigate whether hygienically safe fertilizer could be produced in the different storage options of human excreta. Methods We set up a human excreta storage experiment with 24 storage vaults with different additive matters (lime, rice husk, ashes). Half of vaults had an air ventilation system consisting of a plastic pipe with a series of small holes. The storage options were conducted under conditions similar to those currently used in Vietnamese latrines. Stored excreta were collected every 2 weeks over 6.5 months, giving 336 samples. The number and viability of Ascaris lumbricoides eggs were measured by Romanenko method. pH, moisture content, and temperature of samples were recorded during the storage time. Results The results showed that 92% of A. lumbricoides eggs die-off after 6.5 months of storage for all storage options with the starting pH varied from 7.9 to 10.6 and the temperature varied from 17.4 to 32.6°C. The multivariable linear regression model showed that the parameter found to best determine the A. lumbricoides eggs die-off was the storage period, as it explained 76% of the variation of dead A. lumbricoides eggs. Conclusions The study indicated that a longer storage period is needed for parasite eggs die-off, and the current Vietnamese farmer practice storage of human excreta might be ineffective to kill all of parasitic pathogens over 6 months storage period.
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