Frontiers in Chemical Engineering (Apr 2021)

Microbial Electrochemical Oxidation of Anaerobic Digestion Effluent From Treating HTC Process Water

  • Shixiang Dai,
  • Benjamin Korth,
  • Carsten Vogt,
  • Falk Harnisch

DOI
https://doi.org/10.3389/fceng.2021.652445
Journal volume & issue
Vol. 3

Abstract

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Hydrothermal carbonization (HTC) is a promising technology for chemical and material synthesis. However, HTC produces not only valuable solid coal-materials but also yields process water (PW) with high chemical oxygen demand (COD) that requires extensive treatment. Anaerobic digestion (AD) has been used for initial treatment of HTC-PW, but the AD effluent is still high in COD and particles. Here, we show that microbial electrochemical technologies (MET) can be applied for COD removal from AD effluent of HTC-PW. Bioelectrochemical systems (BES) treating different shares of AD effluent from HTC-PW exhibited similar trends for current production. Thereby, maximum current densities of 0.24 mA cm−2 and COD removal of 65.4 ± 4.4% were reached (n = 3). Microbial community analysis showed that the genus Geobacter dominated anode biofilm and liquid phase of all reactors indicating its central role for COD oxidation and current generation.

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