Physico-chemical and biological changes during co-composting of model kitchen waste, rice bran and dried leaves with different microbial inoculants

Abstract

Disposal of food waste either by land-filling or incineration will cause environmental pollution and engaged in high treatment cost. Composting can be a viable food waste management, however, less research works have focused on the degradation of small scale kitchen waste. In this study, co-composting of model kitchen waste, dried leaves and rice bran were inoculated with four different sources of microbial inoculants (MI) namely commercial Effective Microorganism (EM), Tempeh, Tapai, a mixture of Tempeh and Tapai and water as a control. It was found that the temperature of all four composting materials with MI can be heated up to a higher temperature (>50 \xB0C) than the control and produced less offensive smells. All composts ended with a neutral or weakly alkaline pH value (pH 7 - 8) and a C:N ratio of around 10 which indicating the maturation of composts. For enzymatic activities, the highest activity of amylase (73 - 129 U/g) and cellulase (75 - 148 U/g) occurred at the beginning of the composting process. The maximum activities of lipase (5 - 10 U/g) and protease (46 - 72 U/g) were at the middle stage of the composting process. The germination indexes of the five composts were larger than 100 indicating non-phytotoxic. Although the temperature profile and odour performance were outstanding in the presence of MI, most other parameters did not show significant differences when co-compositing of small scale model kitchen waste was carried out with an adequate initial C:N ratio and moisture content. Further study is needed to distinguish the potential beneficiary effects of MI for the composting of kitchen waste. Nevertheless, the comparable performance of Tempeh and Tapai with EM in composting suggested that Tempeh and Tapai can be used to substitute the function of EM as a cheaper and more available microbial source for the household.