Optimization of C/N and current density in a heterotrophic/biofilm-electrode autotrophic denitrification reactor (HAD-BER)

Bioresour Technol. 2014 Nov:171:389-95. doi: 10.1016/j.biortech.2014.08.117. Epub 2014 Sep 3.

Abstract

In this study, central composite design (CCD) and response surface methodology (RSM) were applied to optimize the C/N and current density in a heterotrophic/biofilm-electrode autotrophic denitrification reactor (HAD-BER). Results showed that nitrate could be effectively reduced over a wide range of C/Ns (0.84-1.3535) and current densities (96.8-370.0 mA/m(2)); however, an optimum C/N of 1.13 and optimum current density of 239.6 mA/m(2) were obtained by RSM. Moreover, the HAD-BER performance under the optimum conditions resulted in almost 100% nitrate-N removal efficiency and low nitrite-N and ammonia-N accumulation. Furthermore, under the optimum conditions, H2 generated from water electrolysis matched the CO2 produced by heterotrophic denitrification by stoichiometric calculation. Therefore, CCD and RSM could be used to acquire optimum operational conditions and improve the nitrate removal efficiency and energy consumption in the HAD-BER.

Keywords: Central composite design (CCD); HAD-BER; Nitrate reduction; Optimization; Response surface methodology (RSM).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Bacteria / metabolism*
  • Biofilms*
  • Bioreactors*
  • Carbon / analysis
  • Carbon Dioxide / metabolism
  • Denitrification / physiology*
  • Electrolysis
  • Groundwater / chemistry*
  • Heterotrophic Processes / physiology
  • Hydrogen / isolation & purification
  • Nitrates / metabolism*
  • Nitrogen / analysis
  • Sewage / microbiology
  • Spectrophotometry, Ultraviolet
  • Water Purification / methods*

Substances

  • Nitrates
  • Sewage
  • Carbon Dioxide
  • Carbon
  • Hydrogen
  • Nitrogen