Topic Area: 1h. Optimization of Classical Bioremediation Technologies

Formatted Title:

Biochar Facilitates Revival and Performance of a PCE-Dechlorinating Consortium

Background/Objectives:

Bioaugmentation of organohalide-respiring microbial consortia to achieve anaerobic reductive dechlorination of chlorinated ethenes (CEs) is a frequent groundwater bioremediation strategy. However, field-scale CE bioremediation strategies can suffer from accumulation of daughter products cis-dichloroethene (cis-DCE) and vinyl chloride (VC) that are more toxic than parent CEs. Pyrogenic carbonaceous matter (PCM) (e.g., biochar or activated carbons), some of which are used as sorbents to contain CEs in groundwater, have also been shown to have physiochemical properties that promote CE (e.g., tetrachloroethene [PCE] and trichloroethene [TCE]) dechlorination. The purpose of this study was to investigate the effects of PCM (i.e., biochar) properties on PCE dechlorination performance (i.e., ethene production) and methanogenesis of a commercially available anaerobic (PCE)-dechlorinating consortium (SDC-9), especially when the initial abundance and activity of the critical microbe, Dehalococcoides, is low.

Approach/Activities:

Twelve experimental bottles (and 1 killed control) were constructed and inoculated with SDC-9 culture previously stored at 4°C for two years without feeding. Poplar biochar (2 g/L), pyrolyzed under four different temperatures (350°C, 500°C, 700°C, 900°C), was used in triplicate treatment sets. Duplicate live control bottles contained no added materials, and another set of duplicate live controls contained 2 g/L sand. Biochar properties (e.g., elemental composition, atomic ratio, surface area, pore volume, pore size, zeta potential, conductivity, and electron-donating capacity) were determined. DNA was extracted from liquid samples during the experiment, and DNA and RNA was extracted from both biochar and liquid samples at the end of the experiment (i.e., after 52-82 days). Biomarker gene abundance for Dehalococcoides (16S rRNA gene, and reductive dehalogenase genes vcrA and tceA) and methanogens (methyl-CoM reductase gene mcrA) was quantified with qPCR. DNA and RNA extracted from biochar and liquid samples was also sequenced and analyzed with a bioinformatics pipeline.

Sumbul Hafeez

Affiliation

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(Group 2, Poster Board #83) Biochar Facilitates Revival and Performance of a PCE-Dechlorinating Consortium