Anaerobic mesophilic and thermophilic treatability of vegetable oil refining wastewater

Two anaerobic filter reactors, one mesophilic (35 °C) and one thermophilic (55 °C), were operated with a vegetable oil refining wastewater at varying organic loadings. The organic loading rates (OLR) applied were in between 0.98-9.96 kg COD/m3/d with a constant hydraulic retention time (HRT) of 24 h for each filter reactor. The maximum chemical oxygen demand (COD) removal rates were 97% and methane yield 0.39 ± 0.02 L CH4/g CODremoved for each filter reactor. The volatile fatty acids (VFA) concentration in the effluents of mesophilic and thermophilic filter reactors also increased proportionally with the loading rate. The results show that both reactors gave the similar COD removal and methane yield. The data obtained for both mesophilic and thermophilic reactors were then applied to the Stover-Kincannon model and Umax and KB values were determined as 40 g/L day, 44.09 g/L day and 111.11 g/L day, 122.78 g/L day, respectively.