Influence of organic loading rate on the anaerobic treatment of high strength semisynthetic waste waters in a biological fluidized bed

The results of anaerobic digestion in a fluidized bed reactor fed with municipal waste waters enriched with glucose are presented. Several process conditions have been tested by varying the influent chemical oxygen demand (COD) from 4 to 13 kg m⁻³ and the residence time from 5.0 to 68.2 h. The degradation efficiency and methane production rate are substantially affected by an increase in organic loading rate from 4 to 24 kgCOD_i m⁻³ day⁻¹, suggesting a maximum operational value for this parameter. Using a Monod-type kinetic model, a maximum theoretical specific degradation rate of 1.76 kgCOD_r kgVSS⁻¹ day⁻¹ has been calculated, which is very similar to values calculated for other effluents from food industry activities.