Biotreatment of Liquid, Solid or Gas Residues: An Integrated Approach

Abstract

Research workers from U AMI and ORSTOM have being working for the last 15 years in an effort to study solid, liquid and gas fermentation systems in order to try to understand their potential and limitations for remedial environmental purposes. Among the main results to be cited: a) A comprehensive model of mycelial growth and metabolic activity, based on experimental evidence taken at microscopic level by image analysis, gasometric studies (on line barometric and gas analysis) and thermometry (heat and mass balances). b) As a result, a new scale-up strategy for solid and gas fermentation systems has been developed based on the conservation of heat and water content of the fermentation mash. c) The limitation of biomass activities in terms of surface and volume hindrances, as a fundamental constraint for densely packed bioreactors has been studied. d) Fundamental work has been done in relation to the biochemical and microbiological mechanisms of film and particle formation in anaerobic digesters. e) New strategies have been developed for the production and selection of mutant microbial strains specially adapted to solid fermentation systems. t) New approaches have been developed for reusing spent biomass and solid residues in agriculture and livestock production.As examples of possible applications of these studies the following can be mentioned: a) The use of Aspergillus niger grown on coffee pulp to reduce its caffeine level, to produce pectinases and to generate a solid residue with probiotic activity in the rumen; b) The use of bioscrubbers to remove from the air various fouling sulfur compounds in a cellophane factory; c) Removal of recalcitrant compounds in industrial waste water 221