Modeling hydraulic transport and anaerobic uptake by PAOs and GAOs during wastewater feeding in EBPR granular sludge reactors.
New-generation bioprocesses using granular sludge aim for a high-rate removal of nutrients from wastewater with low footprint. Achieving enhanced biological phosphorus removal (EBPR) relies on the design of sludge beds and wastewater feeding conditions to optimally load the biomass and to select for polyphosphate- (PAOs) over glycogen-accumulating organisms (GAOs) and over other heterotrophs. A hydraulic-metabolic mathematical model was developed to elucidate the impact of hydraulic transport patterns and environmental conditions on the PAO/GAO competition during up-flow feeding through an EBPR granular sludge bed. Tracer experiments highlighted plug-flow regimes with dispersion under both rapid (9 m h-1, Rebed= 1.6, Pez= 7.2, Pet= 4.6) and slow (0.9 m h-1, Rebed= 0.2, Pez= 21.3, Pet= 3.4) feeding. Non-turbulent regimes (Rebed<< 103) promote a safe implementation of simultaneous fill/draw. Feeding time, pH, and temperature significantly impacted bacterial competition for carbon uptake under anaerobic slow feeding. Feeding duration should be designed to avoid full depletion of intracellular storage polymers within static granules. PAOs bear twice longer feeding than GAOs by using both polyphosphate and glycogen hydrolysis to sustain anaerobic C-uptake. Alkaline conditions (pH 7.25-8.0) by, e.g., dosing lime in the feed select for PAOs independently of temperature (10-30°C). A twice higher bed is required for full anaerobic conversions at 10 rather than 20°C. Biosystem responses for anaerobic C-uptake can be anticipated using the model toward designing robust anaerobic selectors to manage the microbial resource in EBPR granular sludge. Biotechnol. Bioeng. 2017;114: 1688-1702. © 2017 Wiley Periodicals, Inc.
ETH Zürich, Institute of Environmental Engineering, Zürich 8093, Switzerland.|Eawag-Swiss Federal Institute of Aquatic Science and Technology, Dübendorf 8600, Switzerland.|School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland.|Department of Biotechnology, Delft University of Technology, Delft 2629 HZ, The Netherlands.
David G
0000-0002-6313-1652
DG
Weissbrodt
School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland.
Christof
C
Holliger
ETH Zürich, Institute of Environmental Engineering, Zürich 8093, Switzerland.|Eawag-Swiss Federal Institute of Aquatic Science and Technology, Dübendorf 8600, Switzerland.
Eberhard
E
Morgenroth
D001421:Bacteria, Anaerobic / Q000502:physiology*; D019149:Bioreactors / Q000382:microbiology*; D049109:Cell Proliferation / Q000502:physiology; D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008954:Models, Biological; D010758:Phosphorus / Q000302:isolation & purification / Q000378:metabolism*; D011122:Polyphosphates / Q000378:metabolism; D012722:Sewage / Q000382:microbiology*; D013045:Species Specificity; D062065:Wastewater / Q000382:microbiology*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification / Q000378:metabolism; D018508:Water Purification / Q000295:instrumentation*
D010758:Phosphorus; D011122:Polyphosphates; D012722:Sewage; D062065:Wastewater; D014874:Water Pollutants, Chemical
EBPR; PAO/GAO selection; aerobic granular sludge; feeding and environmental impacts; hydraulic-metabolic model; system analysis and mathematical modeling