Design, Construction and Modeling of Upflow Anaerobic Filters Separated in Two and Three Phases

Abstract

In this study, the models for the design of upflow anerobic filters separated into two and three phases at laboratory scale are statistically adjusted, DI-FAFS and TRI-FAFS, respectively. Both reactors have been evaluated in the COD elimination performance by applying a factorial design 33, for a total of 54 tests. The experimental factors are three: the volumetric organic load has been set at 2.25, 3.45 and 4.64 kg COD m-3 d-1, the temperature at 20, 27 and 34 ° C, the depth relationships D1 / D2: 20% / 80%, 50% / 50% and 80% / 20% in the DI-FAFS and D1 / D2 / D3: 4% / 16% / 80%, 10% / 10% / 80% and 16% / 4% / 80% in the TRI-FAFS. The surface hydraulic load was equal to 1.82 m3 m-2d-1. The filter total depth was equal to 1.2 m. The packing medium consisted of a plastic material with a surface area equal to 476.35 m2 m-3. The hydraulic retention time varied between 16 and 18 h. The flow rates between 3.5 and 4 ml min-1. The efficiencies in organic matter elimination in the DI-FAFS varied between 27 and 72.86%; in the TRI-FAFS between 84 and 92%. The maximum efficiencies were achieved in the DI-FAFS with relation D1 / D2: 20% / 80%, and in the TRI-FAFS with relation D1 / D2 / D3: 10% / 10% / 80% for temperatures ≥ 27 ° C and VOL ≥ 3.45 kg COD m-3 d-1. The conceptual model is based on Equations deduced from a mass balance under stationary conditions dS / dt = 0 and advective dS / dZ 0; formulating eight equations applicable to the DI-FAFS and TRI-FAFS reactors; four Equations for each reactor; as follows: 1) Equations 12 and 16 are based on the Velz Equations, (1948); Germain, (1966) and Albertson, (1984); 2) Equations 13 and 14; 17 and 18 are based on the Equations of Van't Hoff-Arrhenius, (1884); Velz, (1948); Schultze (1960); Germain (1966); Albertson (1984), and 3) Equations 15 and 19 are based on the Equations of Van't Hoff-Arrhenius, (1884); Velz, (1948); Germain, (1966) and Albertson, (1984); Schultze, (1960). These equations were compared with the equation of Phelps, (1944) to obtain the parameters of degradation of organic matter. Equations (14) and (18) resulted in an R2 adjusted greater than 0.7; the standard error of estimation and the absolute average error resulted in the minimum value in Equations (14) and (18) with respect to the rest of the Equations.