KINETICS OF AN ANAEROBIC FLUIDIZED-BED SYSTEM USED FOR THE PURIFICATION OF FRUIT PROCESSING WASTE-WATER

A study of the kinetics of the anaerobic digestion of fruit processing waste-water was carried out. A 1.25 1, fluidized bed bioreactor operating at 35-degrees-C and containing a saponite-immobilized biomass at a concentration of 8.95 g volatile suspended solids (VSS) per litre was used. The bioreactor worked satisfactorily in a range of hydraulic retention times from 2.5 to 12.5 days and eliminated more than 97% of the initial chemical oxygen demand (COD) in all instances. Guiot's kinetic model was used to determine the macroenergetic parameters of the system, and showed it to have a yield coefficient for the biomass Y of 0.090 g VSS per g COD and a specific rate of substrate uptake for cell maintenance m of 0.035 (g COD per g VSS) day-1. The experimental results also showed the rate of substrate uptake (R(s), g (COD per g VSS) day-1) correlated with the concentration of biodegradable substrate (S(b), g COD 1-1) through an equation of the Michaelis-Menten type.