Parametric study on mechanical separation system for trash removal from fresh fruit bunches (FFB) consignment in palm oil mills

This study addresses the persistent issue of trash contamination in fresh fruit bunch (FFB) consignments delivered to palm oil mills, which negatively impacts the oil extraction rate (OER) and the quality of crude palm oil (CPO). Trash, comprising sand, soil, stones, and vegetative matter, has been found to increase the free fatty acid (FFA) content and degrade the deterioration of bleachability index (DOBI) of CPO. These quality issues reduce the market value of the oil and limit its application potential. To solve this problem, a mechanical separation system (MSS) prototype was developed. The MSS, designed as a vibrating screen with gap sizes of 15, 30, and 45 mm, was tested for its effectiveness in removing trash from FFB consignments under both dry and wet conditions. Statistical analyses, including ANOVA and paired t-tests, confirmed the significant impact of gap size and environmental conditions on separation efficiency. Among the tested configurations, the 30 mm gap size provided the optimal balance between efficient trash removal and minimal loose fruit loss, thereby maximising overall milling performance. In addition, the MSS showed a strong positive correlation between trash removal and OER improvement, with 1.019% increase in OER observed following the implementation of the system. This study highlights the importance of efficient trash removal and separation in improving CPO quality, increasing OER, and promoting sustainable practices within the palm oil industry. Future research should focus on the economic feasibility analysis of large-scale MSS adoption, integration of automated monitoring systems, and comprehensive assessment of the downstream impacts of trash removal on refining and bleaching processes.