Treatment of a low concentration industrial chemicals mixture in an UASB reactor

A wastewater containing a mixture of methanol, isopropyl alcohol, ethylene glycol, acetic anhydride, methyl, ethyl and isopropyl acetate, acrylic acid, butyl and methyl acrylate, o, m and p-xylene and styrene was fed to an UASB reactor. Isopropanol addition diminished the removal efficiency to 60% and required a long adaptation time for its total mineralization. When acrylic acid was added to the mixture, the removal dropped to 83% and recovered after 40 days. As for the rest of the substrates, p-m-o-xylene addition had no effect on reactor performance, although in batch assays it showed low mineralization. Also the effect of volumetric organic load on removal efficiency was followed up. After diminishing the HRT to 4 and 3 h yielding 4.8 and 6.5 gCOD L⁻¹ d⁻¹, removal efficiencies decreased to 79 and 74% respectively.