CFD for wastewater treatment: an overview

Abstract

Computational fluid dynamics (CFD) is a rapidly emerging field in wastewater treatment (WWT), with application to almost all unit processes. This paper provides an overview of CFD applied to a wide range of unit processes in water and WWT from hydraulic elements like flow splitting to physical, chemical and biological processes like suspended growth nutrient removal and anaerobic digestion. The paper's focus is on articulating the state of practice and research and development needs. The level of CFD's capability varies between different process units, with a high frequency of application in the areas of final sedimentation, activated sludge basin modelling and disinfection, and greater needs in primary sedimentation and anaerobic digestion. While approaches are comprehensive, generally capable of incorporating non-Newtonian fluids, multiphase systems and biokinetics, they are not broad, and further work should be done to address the diversity of process designs. Many units have not been addressed to date. Further needs are identified throughout, but common requirements include improved particle aggregation and breakup (flocculation), and improved coupling of biology and hydraulics.

Towards a robust CFD model for aeration tanks for sewage treatment – a lab-scale study

“…Further, comprehensive discussion on the CFD models applied to analyze, evaluate and optimize performance of the existing AS systems can be found in Karpinska and Bridgeman (2016) and Samstag et al (2016).…”

A comprehensive hydrodynamic analysis of a full-scale oxidation ditch using Population Balance Modelling in CFD simulation

“…On the other hand, the Eulerian approach is the most commonly used in multiphase gas-liquid flow in full-scale aeration tanks. Comparing workability of different options in multiphase modelling, the other approaches available (Lagrangian particle tracking or Volume Of Fluid), despite being more accurate, are exceedingly expensive in terms of computing time and memory [15]. Population Balance Models (PBMs) represent a powerful modelling framework for the description of the dynamics of properties that are characterised by statistical distributions [16].…”

Adjustment of reactor model in organic matter removal from wastewater applying numerical residence time distribution analysis

“…Steady-state rANS model with k-ɛ turbulence closure was applied. Despite the fact that this approach assumes isotrophic turbulence [12], it is well tested and widely accepted in wastewater applications [4]. SImPle (Semi-Implicit method for Pressure linked equations) scheme was applied for velocity-pressure coupling and second-order upwind techniques was applied for spatial discretization [13].…”

“…computational fluid dynamics (cfD) simulation tools are popular in wastewater treatment, numerous research have been done regarding hydraulic aspects of treatment process units, but many processes are not addressed to date [4]. cfD models have primarily been used for design analysis and troubleshooting, but they can be coupled with mass balance (biokinetic) models in which the tank-in-series (TIS) approach is applied widely [5].…”