Abstract:
Composting is one approach for recycling organic waste, that mostly consists of
kitchen and food residue waste. This can be done at household level by use of
in-vessel composters. Sawdust as a bulking agent was used to assess the effect of
bulking agent:food waste (BA:FW) ratio on the stabilising process of food waste in
an in-vessel composter drum. The drum was turned manually at hourly interval at
2 rpm in 5 minutes. Three BA:FW v/v ratios were studied; 2:1,3:1, and 4:1 using
more or less same food waste composition. Temperature, bulk density, moisture,
pH and porosity were monitored over a period of 15 days. Temperature generally
rose to above 45oc within the first 5 days in all the ratios and started to fall after
10days except for 2:1 ratio that remained high even at the 15th day. The moisture
content increased during the process with the highest values occurring in the 2:1ratio.
There was an semi-logarithmic relationship between the bulk density and porosity
across all BA:FW ratios. The pH increased from the initial value of about 4.5 to
between 6 and 7.5. Except for less rapid attainment of thermophilic temperature
and sustainability, the 4:1 ratio generally achieved the best composting conditions.
This study appears to suggest that well rationed BA:FW mixture may be stabilised
rapidly in an in-vessel composter enabling a high turn-over to handle the food waste
generated in a household.
