Prediction of Optimal C: N Ratio in Different Palm Oil Mill Waste Mixtures and Its Evaluation of Earthworm Biomass

Abstract

The oil palm industry has been recognized for its contribution towards economic growth and rapid development, it has also contributed to environmental pollution due to the production of huge quantities of by-products from the oil extraction process. Current research reports prediction of optimal CN ratio of different mixture percentages of palm oil mill effluent (POME) and palm pressed fiber (PPF) namely 100% (only POME), 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10% and 0% (only PPF). Different mixture percentages with varying initial characters results in different C:N ratio which could affect the earthworm growth and the vermicomposting stability. Therefore, the present research aims to predict the optimal mixture by establishing a 3D base model. The models were generated having an average unified formula using mathematical software Matlab. The results obtained in this study indicates that the 3D polynomial graph can explain the relationship between different POME-PPF concentration with respect to earthworm growth and time showing ideal R2 value of 0.99. The regression analysis showed positive correlation between different mixture percentages and earthworm growth in 50% (r = 0.412), 60% (r = 0.509) and 70% (r = 0.441). Therefore, from the model it can conclude that 60% mixture of POME-PPF is an optimal mixture for the vermicomposting process.