Cassava wastes: treatment options and value addition alternatives

Value addition of cassava and cassava wastes is necessitated by rapid post-harvest spoilage, deterioration, low protein content and environmental pollution caused by the effluent and the other associated wastes that poses aesthetic nuisance. Biogas plants of all sizes and varying levels of technical sophistication not only recover the energy contained in cassava wastes but also eliminate most of the animal and human health problems associated with contamination. Studies have shown the technical feasibility and nutritional desirability of converting carbohydrates and their residues into products containing a large amount of protein by means of microorganisms. Wastes transformation offers the possibility of creating marketable value-added products. There exists a great potential in the use of microorganisms such as fungi for the production of high quality feedstuffs from the abundantly available agro-industrial wastes, particularly carbohydrate residues. Cassava wastes can be processed and converted into value-added components such as methane (biogas), pig meat, ethanol, surfactant and fertilizer etc. Attention is now focused on the by-products of the anaerobic decomposition of the waste that takes place in a biodigester, which are the liquid fraction called biol and the solid fraction or biosol, which are excellent fertilizers for a variety of crops. The present review addresses the progress that has been made in each of these aspects with emphasis on the advantages of biol and biosol fertilizers.   Key words: Carbohydrate residue, waste transformation, biofertilizers.