Hythane production from brewery wastewater-generated biogas using a membrane electrochemical cell

Converting organic wastes into hythane, a blend of hydrogen (5% to 25%) and methane (75% to 95%), will not only reduce waste discharge but also maximize energy recovery. Herein, a membrane electrochemical cell was investigated to produce hythane from biogas generated in anaerobic digestion of brewery wastewater (BW). The key parameters including current densities, electrolyte concentrations, and biogas flow rates were examined in batch tests. Under an optimal condition (210 mA, 100 mM electrolyte, 1 mL min⁻¹ of biogas flow), the system achieved the production of hythane containing 70.6% ± 1.1% CH₄, 27.3% ± 0.5% H₂, and 2.1% ± 1.6% CO₂ (corresponding to 91.1% ± 6.4% CO₂ removal). Meanwhile, the H₂S concentration was decreased from 513 to 2 ppm, 99.9% ± 0.2% removal. Energy efficiency of this system was estimated 61.8% ± 10.7%, and energy output increased by 54.4% ± 10.6% with biogas upgrading to hythane. These results encourage further exploration of electrochemical approach for simultaneous biogas upgrading and hythane production. Practitioner Points: An innovative approach is demonstrated for efficient simultaneous biogas upgrading and electrochemical hythane production. Hythane composition is affected by the applied current and biogas flow rate. Biogas from brewery wastewater is converted into hythane with composition of 70.6% ± 1.1% CH₄, 27.3% ± 0.5% H₂, and 2.1% ± 1.6% of CO₂. Electrochemical treatment achieves significant removal of H₂S from the produced hythane.