Leaching of Potassium from Oil Palm Empty Fruit Bunch (OPEFB) Using Tapioca Wastewater

Abstract

Empty fruit bunch (EFB) of palm oil is an abundant by-product that is resulted from the crude palm oil (CPO) extraction process and has great potential for bioenergy application. However, EFB has a high content of mineral such potassium (K) and silica (Si) that result in a negative impact on boiler like ash deposit, corrosive, slagging and fouling during combustion. One of the wise solutions to improve fuel quality of EFB is leaching treatment using tapioca wastewater to reduce its mineral content. It is expected that in addition to fuel quality improvement of EFB, the wastewater is also improved in terms of fertilizer that increase its quality as irrigation water. This study aims to obtain the best combination of soaking time and types of tapioca wastewater in reducing the mineral content of EFB. Wastewater from tapioca mill and effluent from biogas digester were used to wash EFB at a ratio of 1: 40 (w/v). EFB analysis was performed at different soaking durations, namely 0 (control), 5 min, 30 min, 60 min, 90 min, 120 min, 12 hours, and 24 hours. Results showed that wastewater from tapioca mill was more effective to wash metal content in the EFB as compared to biogas digester effluent. Using tapioca wastewater, potassium (K) rapidly decreased from 67.04% to 20.72% in 30 min. Result also indicated that soaking EFB in tapioca wastewater is effective to reduce ash content from 5.97% to 1.13% in 30 min.