Anaerobic digestion of carbohydrate and protein-based wastewaters in fluidized bed bioreactors

M. FUENTES; N.J. SCENNA; P.A. AGUIRRE; M.C MUSSATI;

LATIN AMERICAN APPLIED RESEARCH

UNS-CONICET Printing Office.

Año: 2007 vol. 37 p. 235 - 242

0327-0793

This work deals with an experimental and theoretical investigation of anaerobic fluidized bed reactors (AFBRs) for treating synthetic complex effluents containing carbohydrates as sucrose, and proteins as albumin and gelatin. Bioreactors are modeled as dynamic (gas-solid-liquid) three-phase systems. The anaerobic digestion model proposed by Angelidaki et al. (1999) and parameter data set suggested by Batstone et al. (2002) were selected to describe the substrate degradation scheme and apply it to a biofilm system. The experimental set-up consists of two mesophilic (36±1ºC) lab-scale AFBRs with sand as inert support for biofilm development. The experimental protocol is based on step-type disturbances applied on the inlet substrate concentration and on the feed flow rate considering the criterion of maximum efficiency as the reactor loading rate switching. In a previous paper (Fuentes et al., 2006a), the experimental data obtained during the acclimatization steps (glucose and acetate-based feeding) were used to adjust the model by estimating the empirical values of the rate coefficients for the biofilm detachment model. This work is focused on analysis of bioreactor performance when complex substrates are fed. Some kinetic expressions and parameters, regarding enzymatic hydrolysis, need to be modified to represent the real behavior of bioreactors. Under the analyzed operating conditions, a hydraulic retention time higher than 1 day is suggested to ensure a good system-efficiency.