Abstract
Poultry slaughterhouses discharge large quantities of effluents that can be treated biologically. The objective of this study was to evaluate the chemical oxygen demand (COD) removal efficiency of an upflow anaerobic filter (UAF) with effluents from a poultry slaughterhouse, using volcanic stone (tezontle) as a support medium. Effluent characterization was carried out in accordance with Mexican official standards and standard methods. The support medium was inoculated with activated sludge from an urban wastewater treatment plant. The filter was operated in continuous flow with applied volumetric loads (AVL) of 1, 1.5, 2, 2.5, and 3 kg COD m-3 d-1 and hydraulic retention times (HRT) of 5.8, 3.8, 2.9, 2.3, and 1.9 days. An analysis of variance (ANOVA) was performed, and significant differences were determined for each AVL using the Krustall-Wallis method. The results obtained in the gradually applied AVL were 26.1, 53.2, 40.1, 17, and 49.7 % COD removal. However, in the AVL of 2 and 2.5 kg COD m-3 d-1, there was a decrease in the removal, which is attributed to the destabilization of the system due to the increase in loads. The maximum methane production was 125 mL at an AVL of 3 kg COD m-3 d-1, with a methane yield (YCH4) of 0.082 LCH4 g-1 COD-1rem. With no increase in methane production at each AVL, the theoretical yield of 0.328 LCH4 g-1 COD-1rem. was not met. The upflow anaerobic filter demonstrated its efficiency with a poultry effluent, with maximum COD removal greater than 50 %; however, more acclimatization time is required for the formation of biofilm in the support medium, a pretreatment that removes the high organic load and allows for gradual biogas production.