Availability of micronutrients during anaerobic digestion of molasses stellage using an Upflow Anaerobic Sludge Blanket (UASB) reactor.

Abstract

Abstract During treatment of molasses stillage with an UASB reactor, the essential micronutrients such as Ni2+, Zn2+ and Cu2+ were removed from the UASB sludge matrix due to high concentration of K+ in the influent. The metal analysis of the sludge matrix showed a complete absence of Mo2+ and Co2+. Among the metals analysed in the seeding sludge, Zn (2.08 μg g‐1 Total Suspended Solids, TSS), Ni (625 μg g‐1 TSS) and Cu (2.08 μg g‐1 TSS) were found in low concentration as exchangeable form, when compared to Ca, Fe, Na, and K. It is presumed that presence of K (2.28 g 1‐1) in the 40% diluted molasses stillage is responsible for removal of exchangeable form of micronutrients from the sludge matrix. In summary, it is necessary to add micronutrients to the UASB reactor during anaerobic treatment of K enriched molasses stillage.