Articles by Stephen J. Andersen in JoVE
Electrochemically and Bioelectrochemically Induced Ammonium Recovery Sylvia Gildemyn1, Amanda K. Luther2, Stephen J. Andersen1, Joachim Desloover1, Korneel Rabaey1 1Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, 2Department of Environmental Sciences, Rutgers University We demonstrate the extraction of ammonium from an ammonium-rich stream using an electrochemical and a bioelectrochemical system. The reactor setup, operation and data analysis are discussed.
Other articles by Stephen J. Andersen on PubMed
Dynamically Adaptive Control System for Bioanodes in Serially Stacked Bioelectrochemical Systems Environmental Science & Technology. May, 2013 | Pubmed ID: 23593927 Microbial bioelectrochemical systems (BESs) use microorganisms as catalysts for electrode reactions. They have emerging applications in bioenergy, bioproduction, and bioremediation. BESs can be scaled up as a linked series of units or cells; however, this may lead to so-called cell reversal. Here, we demonstrate a cell balance system (CBS) that controls individual BES cells connected electrically in series by dynamically adapting the applied potential in the kilohertz frequency range relative to the performance of the bioanode. The CBS maintains the cell voltage of individual BES cells at or below a maximum set point by bypassing a portion of applied current with a high-frequency metal oxide semiconductor field-effect transistor switch control system. We demonstrate (i) multiple serially connected BES cells started simultaneously and rapidly from a single power source, as the CBS imparts no current limitation, (ii) continuous, stable, and independent performance of each stacked BES cell, and (iii) stable BES cell and stack performance under excessive applied currents. This control system has applications for not only serially stacked BESs in scaled-up stacks but also rapidly starting individual- and/or lab-scale BESs.
Electrolytic Membrane Extraction Enables Production of Fine Chemicals from Biorefinery Sidestreams Environmental Science & Technology. Jun, 2014 | Pubmed ID: 24844669 Short-chain carboxylates such as acetate are easily produced through mixed culture fermentation of many biological waste streams, although routinely digested to biogas and combusted rather than harvested. We developed a pipeline to extract and upgrade short-chain carboxylates to esters via membrane electrolysis and biphasic esterification. Carboxylate-rich broths are electrolyzed in a cathodic chamber from which anions flux across an anion exchange membrane into an anodic chamber, resulting in a clean acid concentrate with neither solids nor biomass. Next, the aqueous carboxylic acid concentrate reacts with added alcohol in a water-excluding phase to generate volatile esters. In a batch extraction, 96 ± 1.6% of the total acetate was extracted in 48 h from biorefinery thin stillage (5 g L(-1) acetate) at 379 g m(-2) d(-1) (36% Coulombic efficiency). With continuously regenerated thin stillage, the anolyte was concentrated to 14 g/L acetic acid, and converted at 2.64 g (acetate) L(-1) h(-1) in the first hour to ethyl acetate by the addition of excess ethanol and heating to 70 °C, with a final total conversion of 58 ± 3%. This processing pipeline enables direct production of fine chemicals following undefined mixed culture fermentation, embedding carbon in industrial chemicals rather than returning them to the atmosphere as carbon dioxide.