Screening of separator-catholyte pairs for microbial electrolysis cells operated with low buffer-capacity wastewater
Abstract
Microbial Electrolysis Cells (MECs) can treat wastewater and produce hydrogen, but often require a separator between the chambers. The challenges in the efficient separation of reactants and products lie in avoiding pH imbalance, maintaining low ohmic resistance, and minimizing biofouling and crossover. Also, electrolytes heavily influence the separator performance in contact with it. The objective of this work is to identify suitable separator-catholyte pairs for MECs operating with low-conductivity, low-buffer-capacity brewery wastewater. Thus, 7 separators (anion-exchange, cation-exchange, proton-exchange and bipolar membrane and a microporous separator, filtration membrane and cellophane) were tested for area-specific resistance, acetate crossover and biofouling and pH imbalance with 6 catholytes (100 mM H 2 SO 4 , 100 mM NaOH, 100 mM NaCl, 100 mM non-saline phosphate buffer, and semisynthetic brewery wastewater flushed with and without CO 2 ). The results show that AEM-NaOH and BPM-H 2 SO 4 operating abiotically can maintain pH between 5.5 and 7.0, which would keep Geobacter sulfurreducens viable, while other pairs were unable to do so, even without an ongoing fermentation process. Whereas BPM is virtually impermeable to acetate ( D Ac , BPM eff ≈ 5.7 × 10 −13 m 2 s −1 ) and its electrical resistance was similar in both electrolytes studied (∼0.53 kΩ∙cm 2 ), AEM is a more cost-effective option that allows OH‾ transport into the anolyte to control pH. In conclusion, the two less-explored combinations, BPM-H 2 SO 4 and AEM-NaOH, are suitable candidates for double chamber MEC operation. In contrast, the high phosphate leakages, pH imbalance and resistance, when using microporous separators, proton-exchange membranes, or phosphate buffer as catholyte, made them less attractive for MECs.
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BibTeX
@article{vazquez2026screening,
title = {{Screening of separator-catholyte pairs for microbial electrolysis cells operated with low buffer-capacity wastewater}},
author = {Isaac Vázquez and Oksana Bunk and Thomas Papyrin and Guillaume Pillot and Sven Kerzenmacher and Óscar Santiago},
journal = {Journal of Membrane Science},
year = {2026},
month = oct,
doi = {10.1016/j.memsci.2026.125847},
url = {https://hal.science/hal-05805780v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Screening of separator-catholyte pairs for microbial electrolysis cells operated with low buffer-capacity wastewater
AU - Isaac Vázquez
AU - Oksana Bunk
AU - Thomas Papyrin
AU - Guillaume Pillot
AU - Sven Kerzenmacher
AU - Óscar Santiago
PY - 2026
DA - 2026/10/19
JO - Journal of Membrane Science
DO - 10.1016/j.memsci.2026.125847
UR - https://hal.science/hal-05805780v1
AB - Microbial Electrolysis Cells (MECs) can treat wastewater and produce hydrogen, but often require a separator between the chambers. The challenges in the efficient separation of reactants and products lie in avoiding pH imbalance, maintaining low ohmic resistance, and minimizing biofouling and crossover. Also, electrolytes heavily influence the separator performance in contact with it. The objective of this work is to identify suitable separator-catholyte pairs for MECs operating with low-conductivity, low-buffer-capacity brewery wastewater. Thus, 7 separators (anion-exchange, cation-exchange, proton-exchange and bipolar membrane and a microporous separator, filtration membrane and cellophane) were tested for area-specific resistance, acetate crossover and biofouling and pH imbalance with 6 catholytes (100 mM H 2 SO 4 , 100 mM NaOH, 100 mM NaCl, 100 mM non-saline phosphate buffer, and semisynthetic brewery wastewater flushed with and without CO 2 ). The results show that AEM-NaOH and BPM-H 2 SO 4 operating abiotically can maintain pH between 5.5 and 7.0, which would keep Geobacter sulfurreducens viable, while other pairs were unable to do so, even without an ongoing fermentation process. Whereas BPM is virtually impermeable to acetate ( D Ac , BPM eff ≈ 5.7 × 10 −13 m 2 s −1 ) and its electrical resistance was similar in both electrolytes studied (∼0.53 kΩ∙cm 2 ), AEM is a more cost-effective option that allows OH‾ transport into the anolyte to control pH. In conclusion, the two less-explored combinations, BPM-H 2 SO 4 and AEM-NaOH, are suitable candidates for double chamber MEC operation. In contrast, the high phosphate leakages, pH imbalance and resistance, when using microporous separators, proton-exchange membranes, or phosphate buffer as catholyte, made them less attractive for MECs.
SN - 0376-7388
ER -