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Development of a mathematical model to calculate the energy savings and the system running costs through hydrogen recovery in wastewater electrolysis cells

: Kick, Christopher; Apfelbacher, Andreas; Daschner, Robert; Hornung, Andreas

Abstract (PDF; )

Desalination and water treatment 210 (2021), S.44-53
ISSN: 1944-3994
ISSN: 1944-3986
Zeitschriftenaufsatz, Elektronische Publikation
Fraunhofer UMSICHT Sulzbach-Rosenberg ()
hydrogen; wastewater electrolysis cell; Diaphragm; boron-doped diamond electrodes; oxidation of organics

Electrooxidation of wastewater using a wastewater electrolysis cell is known to effectively oxidize persistent organics. However, like other chemical physical treatment methods, the treatment costs are high. The separation of the evolving hydrogen using a diaphragm and the subsequent use of it can help to lower the operational costs of such systems. This paper provides a theoretical basis of the benefits of hydrogen recovery in wastewater electrolysis cells using a diaphragm. The paper discusses all main parameter contributing to the energy demand of the cell as well as to the energy saving potential through hydrogen recovery. The paper lays the theoretical foundation for qualified experiments and is meant to stimulate researchers to proof the proposed concept. The calculations show a maximum theoretical energy saving potential of 45% through the recovery of hydrogen at a minimum cell potential of 2.8 V. The calculations also highlight, that the theoretical energy recovery proportion decreases with rising cell potential as the energy demand of the cell depends on the cell voltage, the hydrogen production rate however does not. In summary, it can be concluded that hydrogen recovery in wastewater electrolysis cells is an effective way of reducing the operational costs and increasing the economic feasibility of electrooxidation systems. Finally, the running costs of the system are compared to wastewater disposal costs.