Efficient Conversion of Aqueous-Waste-Carbon Compounds Into Electrons, Hydrogen, and Chemicals via Separations and Microbial Electrocatalysis

Valorization of waste streams is becoming increasingly important to improve resource recovery and economics of bioprocesses for the production of fuels. The pyrolysis process produces a significant portion of the biomass as an aqueous waste stream, called bio-oil aqueous phase (BOAP), which cannot be effectively converted into fuel. In this report, we detail the separation and utilization of this stream for the production of electrons, hydrogen, and chemicals, which can supplement fuel production improving economics of the biorefinery. Separation methods including physical separation via centrifugal separator, chemical separation via pH manipulation, and electrochemical separation via capacitive deionization are discussed. Bioelectrochemical systems (BES) including microbial fuel cells (MFCs), microbial electrolysis cells (MECs), and electro-fermentation processes are reviewed for their potential to generate current, hydrogen, and chemicals from BOAP. Recent developments in MECs using complex waste streams and electro-active biocatalyst enrichment have resulted in advancement of the technology toward performance metrics closer to commercial requirements. Current densities above 10 A/m2 have been reported using BOAP, which suggest further work to demonstrate the technology at pilot scale should be undertaken. The research on electro-fermentation is revealing potential to generate alcohols, diols, medium chain fatty acids, esters, etc. using electrode-based electrons. The ability to derive electrons and chemical building blocks from waste streams illustrate the advancement of the BES technology and potential to push the frontiers of bioenergy generation one step further toward development of a circular bioeconomy

Assessment of biological nitrogen removal (BNR) in poultry processing facilities

Issued as final reportU.S. Poultry and Egg Associatio

Application of plant biotechnology and bioremediation of contaminated sediments

Issued as Final report, Project E-20-W6

Influence of nonionic surfactants on bioavailability of chlorinated benzenes for microbial reductive dechlorination

Issued as final repor

Fate and effect of naphthenic acids on the biological wastewater treatment processes in oil refineries

Issued as final reportConocoPhillips (Firm

Methanogenic Biocathode Microbial Community Development and the Role of Bacteria

The cathode microbial community of a methanogenic bioelectrochemical system (BES) is key to the efficient conversion of carbon dioxide (CO₂) to methane (CH₄) with application to biogas upgrading. The objective of this study was to compare the performance and microbial community composition of a biocathode inoculated with a mixed methanogenic (MM) culture to a biocathode inoculated with an enriched hydrogenotrophic methanogenic (EHM) culture, developed from the MM culture following pre-enrichment with H₂ and CO₂ as the only externally supplied electron donor and carbon source, respectively. Using an adjacent Ag/AgCl reference electrode, biocathode potential was poised at −0.8 V (versus SHE) using a potentiostat, with the bioanode acting as the counter electrode. When normalized to cathode biofilm biomass, the methane production in the MM- and EHM-biocathode was 0.153 ± 0.010 and 0.586 ± 0.029 mmol CH₄/mg biomass-day, respectively. This study showed that H₂/CO₂ pre-enriched inoculum enhanced biocathode CH₄ production, although the archaeal communities in both biocathodes converged primarily (86–100%) on a phylotype closely related to <i>Methanobrevibacter arboriphilus</i>. The bacterial community of the MM-biocathode was similar to that of the MM inoculum but was enriched in Spirochaetes and other nonexoelectrogenic, fermentative Bacteria. In contrast, the EHM-biocathode bacterial community was enriched in Proteobacteria, exoelectrogens, and putative producers of electron shuttle mediators. Similar biomass levels were detected in the MM- and EHM-biocathodes. Thus, although the archaeal communities were similar in the two biocathodes, the difference in bacterial community composition was likely responsible for the 3.8-fold larger CH₄ production rate observed in the EHM-biocathode. Roles for abundant OTUs identified in the biofilm and inoculum cultures were highlighted on the basis of previous reports