Substrate composition and moisture in composting source-separated human faeces and food waste.
The composting of a faeces/ash mixture and food waste in relative proportions of 1:0, 1:1 and 1:3 was studied in three successive experiments conducted in Kampala, Uganda in 216 L reactors insulated with 75 mm styrofoam or not insulated. The faeces/ash mixture alone exceeded 50 degrees C for < or = 12 days in insulated reactors, but did not reach or maintain 50 degrees C in non-insulated reactors. Inclusion of food waste kept temperatures above 50 degrees C for over two weeks in insulated reactors except when the substrate was too wet. Escherichia coli and total coliform concentrations decreased below detection in material that exceeded 50 degrees C for at least six days. Enterococcus spp. decreased below detection in material that exceeded 50 degrees C for at least two weeks, but remained detectable after 1.5 months in material that exceeded 50 degrees C for less than two weeks, suggesting that a period of at least two weeks above 50 degrees C, combined with mixing, is needed to achieve sanitation. Initially substrates that were too wet proved a challenge to composting and ways of decreasing substrate moisture should be investigated. The results obtained are applicable to the management of small- to medium-scale composting of faeces/ash and food waste at household and institution levels, e.g. schools and restaurants.
Niwagaba
C
C
Department of Civil Engineering, Makerere University, P.O. Box 7062, Kampala, Uganda. charles.niwagaba@et.slu.se
Nalubega
M
M
Vinnerås
B
B
Sundberg
C
C
Jönsson
H
H
D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000378:metabolism; D005243:Feces; D005502:Food; D006801:Humans; D012987:Soil; D013696:Temperature
D012987:Soil