Operation Characteristics and Sludge Properties of the Anaerobic Membrane Bioreactor Treating Lipids-Rich Wastewater

Abstract:

Lipids-rich wastewater is a kind of complex wastewater and easily leads to sludge floating and washingout in the treatment process of conventional anaerobic digestion. In this study，a pilot-scale anaerobic membrane reactor（AnMBR） was adopted to treat the high lipids wastewater，and its operation characteristics and sludge properties were investigated. Results showed that excellent treating efficiency and robust stability were obtained in this systerm，with COD removal efficiency of 99% and VFA concenration below 200 mg/L. However，the digestion efficiency gradually decreased in the late operation stage. Additionally，the hydrolysis products of the high lipids in the influent，the long chain fatty acids（LCFAs），were gradually accumulated in the reactor，which may produce negative effects on the digestion efficiency and sludge properties. Furthermore，the sludge particle size decreased from 26.5 μm to 6.5 μm，while the soluble microbial products（SMP） increased from 47.7 mg/g to 98.0 mg/g and the relative hydrophobicity of sludge elevated from 28.2% to 68.1%. These variations further aggravated the fouling，resulting in an attenuation of flux from 32 L·（m2·h）-1 to 10 L·（m2·h）-1. The pearson correlation test showed that the membrane filtration presented a significant positive correlation with the sludge particle size and a strong negative correlation with the MLSS，SMP and sludge relative hydrophobicity.