During April-June 2022 reporting period, the microbial enrichment experiments have been ongoing using two different setups: anodic and cathodic bio-electrochemical reactors (BERs). The anodic BER experiment is ongoing (entering its third phase) while a cathodic BER was fabricated by the PEER research group and has entered its second phase. During this reporting period, both reactors were being monitored through sample extraction for COD, pH, oxidation-reduction potential (ORP) and VFA measurements. In addition, several electrochemical parameters are being examined which include current production versus time, counter electrode potential measurements, and cyclic voltammetry experiments to assess the electrochemical activity of the attached biofilm on the working electrode. Both reactors are being operated in batch feeding modes with a synthetic feed being prepared for each feeding cycle to replace the present medium. Adjustments are applied to each reactor once performance issues are encountered.
Dr. Wazne's research group has been conducting weekly Zoom meetings with Dr. Haluk Beyenal and his research group for data sharing of the enrichment data and to obtain his expert opinion on ongoing work. The control run for the 20-L UASB has ended and is ready for the second run using the enriched biofilm obtained on the electrodes of the BERs as inoculum. Collected data from that experiment includes CH4 and CO2 quantities, reactor and effluent pH, effluent COD and VFAs and several UASB biomass characterization parameters (SVI and VSS/SS). Furthermore, two new 8-L UASBs are being fabricated from plexi-glass for future runs.
UASB DNA samples from the control reactor (before enrichment) were sent for 16S rRNA high-throughput sequencing on Illumina NovaSeq 6000, Novogene and the preliminary data was analyzed. DNA and RNA extraction Kits, PCR master mixes and primers were purchased for microbial communities’ analyses (from the anode and cathode biofilms as well as UASB granules after enrichment) and for the expression of genes associated with extracellular electron transfer (EET) in the bio-electrodes, prepared and stored for further analyses. Standard curves for qPCR were performed for all primers.
The first manuscript on co-digestion was published in Scientific Reports. Work is still ongoing on the second co-digestion paper where few co-digestion experiments are being repeated and daily monitoring of the associated reactors is ongoing.
June 17-22, 2022, Dr. Wazne gave a presentation on his project at the 17th World Conference on Anaerobic Digestion held at the University of Michigan in Ann Arbor, Michigan, (https://www.iwa-ad17.org/).
In the upcoming months, Dr. Wazne's team will continue the enrichment experiment and use the enriched microorganisms for the acceleration of the startup of the UASB reactor. Dr Wazne expects to complete the repeated experiments for the second co-digestion paper and to have a draft manuscript ready for submission.
