Physicochemical Changes in Co-Composting Process of Palm Oil Mill Sludge (POMS) and Solid Waste (Kitchen Waste) Using Bin Composter

Composting palm oil mill sludge (POMS) together with solid waste (SW) was conducted using a bin composter reactor. Reactor was selected to be used in this study, since it is economical and is a simple alternative compared to other existing composting systems.Co-composting of POMS and SW can be regarded as an environmental-friendly approach when compared to the current method which is disposing waste in landfills. The objective of this study is to find out the potential of the composting process using the proposed substrate and the possible usages of the compost for agricultural activities. Besides, the physicochemical changes that occurred during the entire process of composting POMS together with solid waste were also studied. The highest temperature achieved was about 43 °C, and eventually dropped to 18 °C in the stages which followed. The pH value also decreased along the process and the final pH recorded was 7.024. Percentage of moisture content reduced from 64 to 50.3 during the process. The initial C/N ratio was 32 and this value went down to 19 after 100 days of composting. Concentration of heavy metals also lowered during the treatment process and was found in the final compost in a very low amount. Nutrients such as potassium (K), phosphorus (P) and nitrogen (N) increased with final concentration of 2.68, 1.3 and 2.26 %, respectively. Percentage of reduction of total organic carbon (TOC %) by 50.23 % was observed, with final percentage of 40.21 %. Results obtained from co-composting POMS with SW shows a high potential as an alternative treatment to the disposal and recycling of waste components.