Key points are not available for this paper at this time.
Hydrothermal Liquefaction (HTL) is a promising technology for biomass valorization, but effective treatment of the aqueous byproduct presents an unresolved challenge. Wet oxidation (WO) offers a potential solution to provide heat for a future integrated process and produce large amounts of biogenic carbon dioxide (CO 2 ). This study investigates non-catalytic WO in a continuous flow reactor for treating the HTL aqueous phase (HTL-AP) derived from cattle manure and wheat straw, focusing on oxidation efficiency and degradation products. To explore thermal integration potential, the WO process was operated at residence times (12–45 min) and reaction temperatures (350–365 °C) resembling those of HTL. For the first time, different stoichiometric ratios (0.5–2 times the chemical oxygen demand (COD)) were evaluated, using air and hydrogen peroxide as oxidants. WO using air at 350 °C removed 64–85 % of COD and total organic carbon (TOC) and showed almost complete degradation of nitrogen-containing components to ammonium at the most severe conditions. Increasing air beyond stoichiometric oxygen demand had little effect, while enhanced oxidation efficiency was shown for WO with increasing supply of hydrogen peroxide. Acetic acid accumulated under sub-stoichiometric conditions of hydrogen peroxide but degraded with increased oxidant supply. Gas analysis confirmed almost pure CO 2 streams for sub-stoichiometric hydrogen peroxide WO, while WO with air resulted in a nitrogen diluted off-gas, supporting the implications for future use of the biogenic CO 2 for Power-2-x or sequestration applications. Overall, the results show the feasibility for HTL-AP valorization using WO and highlight its potential for integration with HTL.
Schuck et al. (Mon,) studied this question.