A comparison of different support materials in anaerobic fluidized bed reactors for the treatment of vinasse

Three identical anaerobic fluidized bed reactors containing different biomass support media were fed a distillery wastewater at various hydraulic retention times and COD loadings. The support media used were sepiolite, pumice stone and sand; particle diameter was around 0.5 mm in all cases. Start-up of the reactors was achieved within 63 days using a regime that included stepped increases in influent COD concentration and substitution of methanol for part of the wastewater GOD. No significant differences in performance between reactors were observed during this period. Six different steady states at hydraulic retention times between 0.5 and 2.48 days were studied. Results obtained at these steady states showed similar performances in all three reactors except at HRT of 0.5 days, when the reactors containing sepiolite and pumice stone achieved better COD removal efficiencies and higher methane yields than the rand-containing reactor. It was concluded that sepiolite and pumice stone would be excellent solid supports in biological fluidized bed processes and have a lower energy consumption than the one demanded when using a sand support.