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.

Anaerobic treatment of propylene glycol-contaminated domestic wastewater and microbial community profile at threshold ratio

“…40 g COD/L/d. Moreover, compatible with the results of this particular study; Watari et al. (2015) also reported ca.…”

“…40 g COD/L/d. Moreover, compatible with the results of this particular study; Watari et al (2015) also reported ca. 91% COD removal with 82% methane recovery at a high-rate anaerobic reactor fed by industrial wastewater including 8% ethylene-and 2%…”

“…(2019) . Although Watari et al. (2015) reported much higher OLRs (i.e., up to 13 kg/m 3 .d) are applicable for high-rate anaerobic reactors; high propylene glycol ratios caused significant reduction in biogas production as well as in soluble organic matter removal (i.e., down to ca.…”

“…On the other hand, Synergistetes nearly doubled its relative abundance; however Proteobacteria -a bacterial phylum reported as denitrifying bacteria-were no longer detected in the biomass sample taken on 154-d of operation which might be due to possible inhibition depending on the concentration of glycol available in domestic wastewater (Chen et al, 2019). Watari et al (2015) also reported one of the predominant microbial groups as the phylum Synergistetes next to the phyla Proteobacteria, Euryachaeota, Bacteroidetes, and Firmicutes. Another study by Swiatczak et al (2017) also observed that the acetogenic Synergistes sp.…”

“…Total VFA concentrations increased up to more than 5500 mg/L at the final operating day when Type 2 ADF was 2.7% in a similar study by Goktas et al (2019). Although Watari et al (2015) reported much higher OLRs (i.e., up to 13 kg/m 3 .d) are applicable for high-rate anaerobic reactors; high propylene glycol ratios caused significant reduction in biogas production as well as in soluble organic matter removal (i.e., down to ca. 0.03 m 3 /kg sCOD influent and 11%, respectively) in batch systems.…”