page_title: Microbial electrolysis carbon capture
section_title: Background
hierarchical_section_title: Microbial electrolysis carbon capture / Background
caption_attribution_description: English: This is an upgraded version of en:Aerated Sludge 1.jpg which was uploaded by Kekel on July 4, 2006. The reasons for upgrading the image are: (1) To convert the lossy jpg (which already has visible artifacts) to the non-lossy png format. (2) To shorten the width of the image (from 417px to 300px) so that it can placed on the right side of a Wikipedia article and still have room for the article text. {3) To rename it from "Aerated Sludge 1" to the more appropriate "Activated Sludge 1", since it is now and will continue to be used in the en:Activated Sludge article. The actual changes to the original version are quite minor and the actual appearance of the upgrade version is almost identical with the original. I will retain the same license as used by the original uploader.
context_page_description: Microbial electrolysis carbon capture is a carbon capture technique using microbial electrolysis cells during wastewater treatment. MECC results in net negative carbon emission wastewater treatment by removal of carbon dioxide during the treatment process in the form of calcite, and production of profitable H₂ gas.
  Anthropogenic carbon dioxide emissions contribute to significant regional climate change due to the compound's contribution to the greenhouse gas effect in the atmosphere. Most mitigation goals to remove CO₂ from the atmosphere are based on high levels of CO₂ produced by fossil fuel combustion as a basis for energy production. The use of fossil fuels emits CO₂ and other toxic compounds such as SOₓ and NOₓ in the process of combustion. Economic growth is reliant on energy production for transportation and industrial production of goods and services, the amount of CO₂ emitted is predicted to continue to increase in the foreseeable future.
  Wastewater processing reflects a small percentage of greenhouse gas emissions. Currently, wastewater treatment consumes "3% of total electricity within the U.S."
context_section_description: Wastewater treatment plants are held accountable by The 2004 Greenhouse Gas Protocol Initiative for their emissions of greenhouse gases by the use of electricity to treat wastewater. For example, energy is required for the aeration process that releases volatile compounds from the water, and also for the mixing and transportation of polluted and recycled fluid moving throughout the process. The electricity generation process itself necessary for wastewater treatment produces CO₂, CH4, and nitrous oxide. The aerobic treatment step of the water releases N₂O and CO₂, similar to the particle settling step, and the activated sludge step releases both CO₂ and methane.
  Microbes in wastewater have the potential to enhance mineralization of CO₂. Mineralization of CO₂ into CaCO₃ immobilizes CO₂ which prevent leakages by stabilizing underground pressure and reducing permeability of the cap rock. By Le Chatelier's principle, increasing Ca²⁺ availability and increasing pH will increase the rate of mineralization. Negatively charged surfaces on microbes have a high affinity for cations such as Ca²⁺ and, though metabolic function, increase saturation of CO₂ in solution. In addition, bacterial ureolysis (hydrolysis of urea) increases pH of the solution.
caption: The activated sludge step in wastewater treatment releases compounds such as methane and CO2.
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