Production of Recycled Paving Stones from Spent Bleaching Earth

  • G.A. Mouthe Anombogo
  • P. Ze Bilo’O
  • C. C. Ndjeumi
  • R. Domga
  • A. Danebe Kada
  • Adamou Abdourhaman


The Garoua branch of cottonseed oil refinery (SODECOTON) uses in its process a significant amount of bleaching earth for discoloration of cottonseed oil. After usage, this bleaching earth is qualified as solid waste and considered to be one of the major problems of waste management encountered by this cottonseed oil refinery. The Garoua branch of cottonseed oil refinery uses about 768 kg of bleaching earth per day to decolorize its oil and rejects an average of 949.22 kg of used earth. SODECOTON therefore daily rejects out of the process an average of one ton of Spent Bleaching Earth (SBE). For the sake of upgrading this solid waste by manufacturing recycled paving stones and simultaneously protecting the environment, it was treated through waste inerting process. The amount of fat, the pH value, and relative humidity of the spent bleaching earth are the main physicochemical characteristics that were determined. From physicochemical characterization, it appeared that fat has an average value of 19.68%, while pH and relative humidity are presenting average values of 8.04 and 12.64% respectively. Recycled paving stones produced showed physicochemical recycled paving with a compressive strength of 28.81 MPa, a resistance force of 815.03 kN, a water absorption rate of 11% and economic advantages than concrete cement pavers encountered in the local market.Keywords: Fat, Relative humidity, Plastics, Spent Bleaching Earth, Recycled paving stones