Enhancement of palm oil refinery waste – Spent bleaching earth (SBE) into bio organic fertilizer and their effects on crop biomass growth

Abstract

Spent bleaching earth (SBE) derived from the degumming and bleaching of crude palm oil (CPO) from physically refined palm oil is commonly disposed off at landfills at a high cost. Its disposal has so far led to environmental degradation but has not been addressed. This study demonstrates the innovative utilization of SBE as a bio organic fertilizer. The SBE was co-composted with some agricultural and palm oil milling by-products. Composted SBE has a positive impact on soil physical attributes for plant growth and microbial rejuvenation due to adequate amounts of beneficial mineral elements; improved organic carbon (OC); cation exchange capacity (CEC); water-holding capacity and C:N ratio. The pot and field trials carried out indicate highly significant increases in the productivity of okra (Abelmoschus esculentus), kangkung (Ipomoea aquatic) and groundnut magenta with 2-fold increases (35–60%) on average in fresh and dry matters production.