Biogas as an alternative energy source is getting more attention which can facilitate to reduce fossil fuel utilization and greenhouse gas emissions. However, biogas is a mixture of gases and typically composed of 60-70% v/v methane (CH4) and 30-40% v/v carbon dioxide (CO2), small amounts of hydrogen sulfide (H2S) and other gases. Rude biogas exhibits a significantly low Wobbe index, heating value and energy efficiency which hinder its application. Therefore, CH4 enrichment prior to use is crucial to improve the quality of biogas. In this work, a novel bipolar membrane-microbial electrolysis cell (BPMEC) was proposed to realize biogas upgrading. The system was composed of the anode, middle and cathode chamber which were separated by a bipolar membrane (BM) and an anion exchange membrane (AEM), respectively. With an external potential, water dissociation occurred and acid was produced in the middle chamber while electrolysis happened and alkali was generated in the cathode chamber. When rude biogas was injected into the cathode chamber, CO2 was absorbed chemically into the solution and migrated via AEM as the form of CO32- and HCO3- into the middle chamber where they reacted with H+ and CO2 was regenerated and released from the solution. The gas flow rates were varied, as well as the external voltage. Results revealed the highest cathodic pH was 10.03±0.21 and the lowest pH in the middle chamber was 1.34±0.21. The highest CO2 removal efficiency can be reached at 98.76±1.32% and the maximum CH4 content can be 98.13±1.12% with 19.64 ml/h gas flow rate and 1.2 V external potential. Organic matter was removed remarkably and COD of the last day was below 60 mg/l. Hydrogen (H2) was produced and collected in the enriched gas which is another benefit of the system. This study provides a simple, efficient and sustainable way to extend the application of electrochemical technology.
|Number of pages||1|
|Publication status||Published - 2016|
|Event||Sustain-ATV Conference 2016: Creating Technology for a Sustainable Society - Technical University of Denmark, Kgs. Lyngby, Denmark|
Duration: 30 Nov 2016 → 30 Nov 2016
|Conference||Sustain-ATV Conference 2016|
|Location||Technical University of Denmark|
|Period||30/11/2016 → 30/11/2016|