Biochar as a Rechargeable Geobattery to Promote Nitrogen Removal in Stormwater from Roadways

Stormwater runoff from roadways is a major source of pollution. State Departments of Transportation (DOTs) must comply with Total Maximum Daily Load (TMDL) regulations for nutrients such as nitrate-nitrogen, which is a major cause of water quality impairment. Existing stormwater treatment technologies, such as bioretention cells, do not remove nitrate adequately to meet water quality standards. New technologies are needed that can reduce nitrate more effectively and thus decrease the footprint required for stormwater treatment. Such technologies will not only improve water quality but also result in significant cost savings for state DOTs. The authors propose that biochar can serve as a rechargeable electron storage medium which, when added to a bioretention cell, can support/promote microbial reductive removal of nitrate in stormwater, and thereby enhance nitrate removal efficiency without increasing treatment footprint. Through batch experiments using a commercial wood-based biochar and the bacterium Geobacter metallireducens (GS-15), the authors showed that air-oxidized biochar served as an electron acceptor to enable acetate oxidation, and that either chemically or microbiologically reduced biochar served as an electron donor for nitrate reduction. The bioavailable electron storage capacity (ESC) of the biochar, estimated based on acetate oxidation and nitrate reduction, was 0.85 and 0.87 mmol e– /g, respectively. The authors propose that biochar should be regarded as a rechargeable reservoir of bioavailable electrons in anaerobic environments, and that biochar may be applied to bioretention cells and other engineered systems to promote microbial degradation of nitrate and other pollutants.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Figures;
  • Pagination: 11p

Subject/Index Terms

Filing Info

  • Accession Number: 01599872
  • Record Type: Publication
  • Report/Paper Numbers: CAIT-UTC-061
  • Contract Numbers: DTRT12-G-UTC16
  • Files: UTC, NTL, TRIS, RITA, ATRI, USDOT
  • Created Date: May 18 2016 2:17PM