TITLE:
Health Risk Assessment of Compost-Amended Soils
AUTHORS:
Hamidatu S. Darimani, Ryusei Ito
KEYWORDS:
Risk Assessment, Enterococcus, Composting Toilet, Soil System, Inactivation Rate Coefficient
JOURNAL NAME:
Journal of Agricultural Chemistry and Environment,
Vol.9 No.2,
May
7,
2020
ABSTRACT: Application of improperly treated compost from composting toilet is one
of the causes of bacterial contamination in the field, crops, food and water.
The study characterized the die-off represented by kinetic inactivation rate
coefficient, k (h-1)
of Enterococcus in clay and sandy loam soils, determined the effect of
temperature, compost-to-soil ratio and soil type on the inactivation rates of Enterococcus and evaluated the health risk associated with the amendment of compost from
composting toilet in real conditions using local climatic data. The
soils were amended with compost to soil ratios of 1:10, 1:25, 1:50 and 1:100
held at different temperatures (30°C, 40°C and 50°C). Inactivation of Enterococcus (pathogenic bacteria) in the soil with high temperature under different
compost application rates was tried in the laboratory test and the Quantitative
Microbial Health Risk evaluated. The study results indicated the inactivation
rates of Enterococcus in clay soils as 0.015 - 0.027 h-1,
0.246 - 0.322 h-1, 0.397 - 0.571 h-1 whilst sandy loam
soils recorded 0.056 - 0.130 h-1, 0.348 - 0.447 h-1 and
0.475 - 0.630 h-1 for 30°C, 40°C and 50°C respectively. Inactivation
rates of Enterococcus in soils amended with compost from the composting
toilet depended on temperature and soil type but not on the compost-to-soil
ratios and compost from the composting toilet amended to the soils is safe for
use in six (6) days.