Tags

Type your tag names separated by a space and hit enter

A new settling velocity model to describe secondary sedimentation.
Water Res 2014; 66:447-458WR

Abstract

Secondary settling tanks (SSTs) are the most hydraulically sensitive unit operations in biological wastewater treatment plants. The maximum permissible inflow to the plant depends on the efficiency of SSTs in separating and thickening the activated sludge. The flow conditions and solids distribution in SSTs can be predicted using computational fluid dynamics (CFD) tools. Despite extensive studies on the compression settling behaviour of activated sludge and the development of advanced settling velocity models for use in SST simulations, these models are not often used, due to the challenges associated with their calibration. In this study, we developed a new settling velocity model, including hindered, transient and compression settling, and showed that it can be calibrated to data from a simple, novel settling column experimental set-up using the Bayesian optimization method DREAM(ZS). In addition, correlations between the Herschel-Bulkley rheological model parameters and sludge concentration were identified with data from batch rheological experiments. A 2-D axisymmetric CFD model of a circular SST containing the new settling velocity and rheological model was validated with full-scale measurements. Finally, it was shown that the representation of compression settling in the CFD model can significantly influence the prediction of sludge distribution in the SSTs under dry- and wet-weather flow conditions.

Authors+Show Affiliations

Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kgs. Lyngby, Denmark. Electronic address: elhr@env.dtu.dk.Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kgs. Lyngby, Denmark. Electronic address: dosaw@env.dtu.dk.DHI Water & Environment (S) Pte Ltd, Singapore 63714, Singapore. Electronic address: lay@dhigroup.com.Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kgs. Lyngby, Denmark. Electronic address: pjbi@env.dtu.dk.Department of Civil Engineering, Aalborg University, Sohngaardsholmsvej 57, 9000 Aalborg, Denmark. Electronic address: mr@civil.aau.dk.Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kgs. Lyngby, Denmark. Electronic address: psmi@env.dtu.dk.Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kgs. Lyngby, Denmark. Electronic address: beep@env.dtu.dk.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

25243657

Citation

Ramin, Elham, et al. "A New Settling Velocity Model to Describe Secondary Sedimentation." Water Research, vol. 66, 2014, pp. 447-458.
Ramin E, Wágner DS, Yde L, et al. A new settling velocity model to describe secondary sedimentation. Water Res. 2014;66:447-458.
Ramin, E., Wágner, D. S., Yde, L., Binning, P. J., Rasmussen, M. R., Mikkelsen, P. S., & Plósz, B. G. (2014). A new settling velocity model to describe secondary sedimentation. Water Research, 66, pp. 447-458. doi:10.1016/j.watres.2014.08.034.
Ramin E, et al. A New Settling Velocity Model to Describe Secondary Sedimentation. Water Res. 2014 Dec 1;66:447-458. PubMed PMID: 25243657.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A new settling velocity model to describe secondary sedimentation. AU - Ramin,Elham, AU - Wágner,Dorottya S, AU - Yde,Lars, AU - Binning,Philip J, AU - Rasmussen,Michael R, AU - Mikkelsen,Peter Steen, AU - Plósz,Benedek Gy, Y1 - 2014/09/03/ PY - 2014/03/31/received PY - 2014/07/25/revised PY - 2014/08/23/accepted PY - 2014/9/23/entrez PY - 2014/9/23/pubmed PY - 2015/8/1/medline KW - Activated sludge KW - Calibration KW - Compression KW - Computational fluid dynamics KW - Monte Carlo Markov Chain KW - Rheology SP - 447 EP - 458 JF - Water research JO - Water Res. VL - 66 N2 - Secondary settling tanks (SSTs) are the most hydraulically sensitive unit operations in biological wastewater treatment plants. The maximum permissible inflow to the plant depends on the efficiency of SSTs in separating and thickening the activated sludge. The flow conditions and solids distribution in SSTs can be predicted using computational fluid dynamics (CFD) tools. Despite extensive studies on the compression settling behaviour of activated sludge and the development of advanced settling velocity models for use in SST simulations, these models are not often used, due to the challenges associated with their calibration. In this study, we developed a new settling velocity model, including hindered, transient and compression settling, and showed that it can be calibrated to data from a simple, novel settling column experimental set-up using the Bayesian optimization method DREAM(ZS). In addition, correlations between the Herschel-Bulkley rheological model parameters and sludge concentration were identified with data from batch rheological experiments. A 2-D axisymmetric CFD model of a circular SST containing the new settling velocity and rheological model was validated with full-scale measurements. Finally, it was shown that the representation of compression settling in the CFD model can significantly influence the prediction of sludge distribution in the SSTs under dry- and wet-weather flow conditions. SN - 1879-2448 UR - https://www.unboundmedicine.com/medline/citation/25243657/A_new_settling_velocity_model_to_describe_secondary_sedimentation L2 - https://linkinghub.elsevier.com/retrieve/pii/S0043-1354(14)00601-0 DB - PRIME DP - Unbound Medicine ER -