Enhanced lipid degradation in an upflow anaerobic sludge blanket reactor by integration with an acidogenic reactor

Lipids inhibition and their degradation in dairy wastewater treatment were investigated in this study. A two-phase system, composed of an acidogenic continuously stirred tank reactor (CSTR) and a methanogenic upflow anaerobic sludge blanket (UASB) reactor, was compared with the single-phase system of a conventional UASB reactor. The systems were operated up to an organic loading rate of 8.09 g chemical oxygen demand (COD)/L·d at a lipid loading rate of 2.94 g COD/L·d. The two-phase system showed better performance in COD removal (1.19 times), lipids removal (1.92 times), and methane production (1.42 times) compared with the single-phase system. The degradation of lipids and the saturation of the double-bonded lipids in the CSTR enhanced the performance of the system. In serum bottle tests at different lipids concentrations, a high lipids concentration resulted in a long lag-phase time for methane production. However, 69.5% of COD eventually was converted to methane within 50 days at 6.1 g lipid-COD/L.