Navigating
Wastewater Energy Recovery Strategies:
A Life Cycle Comparison of Anaerobic Membrane Bioreactor and Conventional
Treatment Systems with Anaerobic Digestion
posted on 2014-05-20, 00:00authored byAdam L. Smith, Lauren B. Stadler, Ling Cao, Nancy
G. Love, Lutgarde Raskin, Steven J. Skerlos
The objective of this study was to
evaluate emerging anaerobic
membrane bioreactor (AnMBR) technology in comparison with conventional
wastewater energy recovery technologies. Wastewater treatment process
modeling and systems analyses were combined to evaluate the conditions
under which AnMBR may produce more net energy and have lower life
cycle environmental emissions than high rate activated sludge with
anaerobic digestion (HRAS+AD), conventional activated sludge with
anaerobic digestion (CAS+AD), and an aerobic membrane bioreactor with
anaerobic digestion (AeMBR+AD). For medium strength domestic wastewater
treatment under baseline assumptions at 15 °C, AnMBR recovered
49% more energy as biogas than HRAS+AD, the most energy positive conventional
technology considered, but had significantly higher energy demands
and environmental emissions. Global warming impacts associated with
AnMBR were largely due to emissions of effluent dissolved methane.
For high strength domestic wastewater treatment, AnMBR recovered 15%
more net energy than HRAS+AD, and the environmental emissions gap
between the two systems was reduced. Future developments of AnMBR
technology in low energy fouling control, increased flux, and management
of effluent methane emissions would make AnMBR competitive with HRAS+AD.
Rapid advancements in AnMBR technology must continue to achieve its
full economic and environmental potential as an energy recovery strategy
for domestic wastewater.