TY - JOUR
T1 - Computational Fluid Dynamics Modeling for the Design of Large Primary Settling Tanks
AU - Liu, Xiaofeng
AU - Garcia, Marcelo H.
PY - 2010/8/3
Y1 - 2010/8/3
N2 - Settling tanks are used to remove solids at wastewater treatment plants. Many numerical models have been proposed to simulate the settling process and to improve tank efficiency. In this research, a three-dimensional (3D) numerical model is developed to simulate large primary settling tanks. In the proposed model, the non-Newtonian properties of the sludge flow in the settling tank are described by a Bingham plastic rheological model. To eliminate the singularity inherited in the rheological model, a modified constitutive relation is used in both the yielded and unyielded regions. Hindered settling of particles in the settling tank is also modeled. Tracer study, where a massless scalar is injected and transported, is done to investigate the tank's residence time. This numerical model is used to improve the design of the primary settling tanks, which will be built in Chicago. The Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) is in the process of building new preliminary treatment facilities at their Calumet Water Reclamation Plant (CWRP), including twelve 155-ft-diameter primary settling tanks (PSTs) designed to treat flows up to (480 million gal./day (MGD). The computational fluid dynamics (CFD) model simulated solids removal efficiencies based on a particle size distribution similar to the one observed in the CWRP influent. The results were used to establish the design basis for tank side-water depth, inlet feedwell dimensions, etc., resulting in improved performance and substantial reduction in construction costs.
AB - Settling tanks are used to remove solids at wastewater treatment plants. Many numerical models have been proposed to simulate the settling process and to improve tank efficiency. In this research, a three-dimensional (3D) numerical model is developed to simulate large primary settling tanks. In the proposed model, the non-Newtonian properties of the sludge flow in the settling tank are described by a Bingham plastic rheological model. To eliminate the singularity inherited in the rheological model, a modified constitutive relation is used in both the yielded and unyielded regions. Hindered settling of particles in the settling tank is also modeled. Tracer study, where a massless scalar is injected and transported, is done to investigate the tank's residence time. This numerical model is used to improve the design of the primary settling tanks, which will be built in Chicago. The Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) is in the process of building new preliminary treatment facilities at their Calumet Water Reclamation Plant (CWRP), including twelve 155-ft-diameter primary settling tanks (PSTs) designed to treat flows up to (480 million gal./day (MGD). The computational fluid dynamics (CFD) model simulated solids removal efficiencies based on a particle size distribution similar to the one observed in the CWRP influent. The results were used to establish the design basis for tank side-water depth, inlet feedwell dimensions, etc., resulting in improved performance and substantial reduction in construction costs.
UR - http://www.scopus.com/inward/record.url?scp=79952352034&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=79952352034&partnerID=8YFLogxK
U2 - 10.1061/(ASCE)HY.1943-7900.0000313
DO - 10.1061/(ASCE)HY.1943-7900.0000313
M3 - Article
AN - SCOPUS:79952352034
VL - 137
SP - 343
EP - 355
JO - American Society of Civil Engineers, Journal of the Hydraulics Division
JF - American Society of Civil Engineers, Journal of the Hydraulics Division
SN - 0733-9429
IS - 3
ER -