Application of the Anaerobic Digestion Model No. 1 (ADM1) and an alternative digestion model to biofilm systems in fluidized bed reactors for treating carbohydrate and protein-based wastewaters

FUENTES MORA, MAUREN; SCENNA, NICOLÁS; AGUIRRE, PÍO

Buenos Aires, Argentina

Congreso; XII Interamerican Congress of Chemical Engineering and V Argentinean Congress of Chemical Engineering; 2006

Asociación Argentina de Ingenieros Químicos (AAIQ).

This work deals with the modeling and experimentation of anaerobic fluidized bed reactors (AFBRs) for treating carbohydrate and protein-based wastewaters. Bioreactors are modeled as dynamic (gas-solid-liquid) three-phase systems. Both, the Anaerobic Digestion Model No. 1 (ADM1) proposed by Batstone et al. (2002) (London, UK: IWA Publishing), and an alternative degradation scheme proposed by Angelidaki et al. (1999) are applied to a biofilm system. Two mesophilic lab-scale AFB reactors were used as experimental set-up, and two experimental stages were carried out in both reactors. First, a glucose and acetate-based substrate was fed during the acclimatization stage. Then, synthetic complex substrates such as proteins as albumin and gelatin, and sucrose as a carbohydrate were added to bioreactor feeding during a second stage. Predicted and measured responses of the total and soluble chemical oxygen demands, volatile fatty acid concentrations, biogas production rate and pH were investigated. Experimental data obtained during the acclimatization stage were used to estimate the empirical values of the rate coefficients for the biofilm detachment model. From analyzing experimental data of second stage, it was concluded that some kinetic expressions and parameters, regarding enzymatic hydrolysis, need to be modified to represent the real performances of bioreactors. Regarding fluidization aspects, variations of the bed expansion due to disturbances on the inlet flow rate and the biofilm growth were measured. Under the operating conditions evaluated in this investigation a hydraulic retention time higher than 1 day is suggested to ensure a good system-efficiency.