Performance evaluation and kinetics modeling of a hybrid UASB reactor treating bovine slaughterhouse wastewater

This work aimed to analyze the performance of a hybrid upflow anaerobic sludge blanket (HUASB) reactor packed with natural zeolite for slaughterhouse wastewater treatment through kinetics modeling. Wastewater samples from a municipal bovine slaughterhouse were sieved through a 1-mm mesh screen and thermally pretreated in an autoclave. Then, biological treatment was carried out in a HUASB reactor packed with a zeolite filter at the top. Slaughterhouse wastewater was diluted with municipal wastewater during the start-up period to achieve a low organic loading rate (OLR) (3.4 kg chemical oxygen demand (COD)/m³/day); afterward, it gradually increased until dilution was eliminated, reaching 14.4 kg COD/m³/day. At this OLR, the maximum percentage removals of total COD, soluble COD, total solid, and volatile solid (67.7%, 68.3%, 55.2%, and 72.1%, respectively) were found. Moreover, the zeolite filter enabled NH₄⁺-N and PO₄^3--P removal, with the highest values (32.8% and 35%, respectively) at 9.8 kg COD/m³/day. Thus, the natural zeolite filter improved the reactor's performance. Among all equations analyzed, the modified Stover-Kincannon equation correctly fitted the results and provided the best prediction of the HUASB reactor's performance.