Composting of Oil Palm Empty Fruit Bunches by Microbial Inoculant

Composting is a natural process that occurs as a result of microbial succession and marks the degradation and stabilization of organic matter in waste. The use of microbial additives during composting is believed to be highly efficient, as it increases the production of various enzymes, resulting in a faster rate of waste degradation. The process converts waste into a humus-like substance that can enhance the physical, chemical, and biological properties of soil. In this study, to assess the contribution of microorganisms to the composting process, we selected the thermophilic bacteria degrading Bacillus subtilis-ReK(1)Hs-Cr-1 as the inoculant. The analysis of temperature, pH, moisture, microbial population, compost maturity, seed germination test, and C:N ratio were all monitored during the composting process. Physical changes in the compost, such as color, texture, and smell, were also observed. The findings showed that the inoculation of this thermophile with the addition of chicken manure was able to raise the temperature up to 67.3 degrees C, which may have resulted in the elimination of pathogens, which is above the recommended temperature level of 55 degrees C for 3 consecutive days. There was an increase in the microbial population (4.6 x10(5) -2.9 x10(7)) at the start of the experimental works and the temperature decreased as the composting process proceeded because of the maturity phase. The pH; 7-9 and moisture content; 51-63 % of compost materials were in the range of optimum composting conditions. The weight of the compost materials in all three treatments, except for the control, decreased by 47% to 55%. The color of the compost turned to dark brown, the obnoxious odor was eliminated, and the texture changed to lose and easy pulverize at the final stage of composting. High germination index (GI) was obtained from the test, indicating that the final product is free from phytotoxic substances and thus suitable as soil conditioner/fertilizer. Therefore, B. subtilis ReK(1)Hs-Cr-1 is the best candidate as an inoculant a added with chicken manure to degrade OPEFB on a large scale using windrow technology.