Characterisation and Utilisation of Spent Bleaching Earth from Palm Oil Refining for Brick Production in Rivers State

Spent bleaching earth generated during palm oil refining in Rivers State, South South Nigeria, constitutes a hazardous industrial solid waste currently managed through landfill disposal. This study characterises spent bleaching earth from a palm oil refinery in Elimgbu, Port Harcourt, and investigates its reuse as a partial clay substitute in fired brick production. Spent bleaching earth samples were characterised for residual oil content, particle size distribution, Atterberg limits, X-ray diffraction mineralogy, and heavy metal content. Fired brick test specimens were prepared by blending spent bleaching earth with locally sourced shale clay at replacement levels of 5%, 10%, 15%, and 20% by weight, extruded, and fired at 900 degrees Celsius for 4 hours. Brick specimens were evaluated for compressive strength, water absorption, efflorescence, and dimensional tolerance. Results showed that bricks containing up to 10% spent bleaching earth met the minimum compressive strength requirement of 7 MPa for class L bricks, with water absorption within the acceptable range of 15 to 20%. Heavy metal leaching from fired bricks was below regulatory limits, indicating that firing immobilises metal contaminants effectively. The study provides an alternative waste management route for spent bleaching earth while reducing raw material requirements for brick manufacturing in Rivers State. Keywords: spent bleaching earth, palm oil refinery, fired brick, waste valorisation, Rivers State