(753a) Production of Renewable Hydrogen from Wastewater Using Microbial Electrochemical Systems

Hydrogen is one of the key starting materials used in the chemical industry. Large amounts of hydrogen are also required in biorefinery schemes due to the high O/C and low H/C ratio of biomass. The H2 industry in the USA is large, but virtually all of the H2 today comes from reforming fossil fuels. Capturing renewable H2 stored in organic-rich wastewater would provide a new source of H2 that would also accomplish the wastewater treatment. Dark fermentation, a process that uses fermentative bacteria to convert organic matter to H2 without the presence of light, can achieve relatively high H2 production rates. However, the H2 yield is very low due to the formation of large quantities of side products. Microbial electrolysis cell (MEC) overcomes the fermentation barrier and provides a new approach for generating H2 from biomass. However, the key challenges for realizing the practical applications of MECs, especially for wastewater treatment include: 1) low H2 production rate; and 2) H2 uptake by H2 consumers, such as methanogens and homoacetogens. In this presentation, we will present our recent development of a hybrid microbial electrochemical system that combines the strengths of fermentation and MEC processes in one reactor for efficient H2 production. We will also present some low-cost strategies we developed against methanogens and homoacetogens for enhancing H2 recovery in the hybrid system. Future works, including scaling up and techno-economic analysis, will also be discussed.