You are here:
Dissolved Methane Recovery in an Attached Growth Reactor Anaerobic Membrane Bioreactor Treating Synthetic Domestic Wastewater
Citation:
Crone, B. AND J. Garland. Dissolved Methane Recovery in an Attached Growth Reactor Anaerobic Membrane Bioreactor Treating Synthetic Domestic Wastewater. Water Treatment Interagency Working Group (WaTr), Urbana-Champaign, Illinois, May 22 - 23, 2018.
Impact/Purpose:
The purpose of this presentation is to provide an overview of work being done on improvements in anaerobic membrane bioreactors treating domestic wastewater in order to reduce energy consumption and increase resource recovery. Specifically, this presentation highlights work being done on dissolved methane recovery via a novel attached growth anaerobic membrane bioreactor.
Description:
Activated Sludge treatment of Domestic Wastewater (DWW) requires significant operational energy for aeration. Additionally, chemical energy available in wastewater is oxidized and not recovered for subsequent use. Anaerobic treatment of domestic wastewater uses syntrophic organisms to metabolize available carbon to methane and carbon dioxide. Methane can be collected and combusted to produce electricity to offset operational energy requirements. One of the main barriers to broader application of anaerobic treatment is significant losses of dissolved methane in the effluent, especially at low temperatures which increase methane solubility. In order to more efficiently recovery dissolved methane, a novel attached growth anaerobic membrane bioreactor was developed in which methane is recovered using a vacuum from a biofilm on the surface of Polydimethylsiloxane Hollow Fiber membrane as it is produced. A control reactor without degassing was operated for comparison, and plasma treatment and acid etching of the membrane surfaces was evaluated for improvement of biofilm adhesion and selection of archaea. When operated over 72 weeks between 89-96% of total methane was recovered in the degassed reactors depending on surface treatment with no appreciable decline in recovery efficiency. This is in stark contrast with significant flux declines reported in the literature for effluent degassing membranes due to fouling over time. Overall methane recovery in the control reactor was 39%. Reactors with modified membrane surfaces showed a significant increase in methane yield and the pH in all degassed reactors was higher than the control due to removal of carbon dioxide. An energy balance was performed and compared with energy demands of anaerobic membrane bioreactors reported in the literature. The biofilm was characterized using Fluorescent In-Situ Hybridization and sequencing of 16s ribosomal RNA.