Development of UASB-DHS System for Treating Industrial Wastewater Containing Ethylene Glycol

Abstract

This study evaluated the performance of a novel treatment system consisting of an upflow anaerobic sludge blanket (UASB) and a downflow hanging sponge (DHS) for the treatment of industrial wastewater containing 8% ethylene glycol and 2% propylene glycol discharged from a rubber production unit. The system achieved high COD removal (91 ± 4.3%) and methane recovery (82 ± 20%) at an organic loading rate of 8.5 kg-COD/(m 3 ·day). The UASB allowed an organic loading rate of 14 kg-COD/(m 3 ·day) with a constant hydraulic retention time of 24 h. The COD of DHS effluent was 370 ± 250 mg-COD/L during the entire experimental period. Thus, the proposed system could be applicable for treating industrial wastewater containing ethylene glycol. Massively parallel 16S rRNA gene sequencing elucidated the microbial community structure of the UASB. The dominant family Pelobacteriaceae could mainly degrade the organic compounds of ethylene glycol and decomposed products of ethanol. In Archaea, the hydrogenotrophic methanogen family Methanobacteriaceae was predominant in UASB granular sludge.