Understanding the Residence Time Distribution in a Transient Inline Spiking System: Modeling, Experiments, and...

Area of Science:

• Chemical Engineering
• Bioprocessing Technology
• Filtration Science

Background:

• Transient inline spiking systems offer a method for assessing virus filter performance during continuous operation.
• Understanding residence time distribution (RTD) is critical for optimizing these systems.

Purpose of the Study:

• To systematically analyze the RTD of inert tracers in a transient inline spiking system.
• To investigate the mixing and spreading of a salt spike within processing units, focusing on membrane filtration.

Main Methods:

• A NaCl solution was used as an inert tracer, with spiking duration varied.
• RTD curves were generated by measuring conductivity, analyzed using a PFR-2CSTR model.
• Computational Fluid Dynamics (CFD) simulations were employed to visualize tracer transport.

Main Results:

• The PFR-2CSTR model accurately predicted outlet concentrations with specific time constants (τPFR = 4.3 min, τCSTR1 = 4.1 min, τCSTR2 = 1.0 min).
• RTD curves extended significantly beyond the spiking duration, indicating substantial solute dispersion.
• CFD simulations correlated flow characteristics with observed RTD patterns.

Conclusions:

• The study provides a detailed analysis of the transient inline spiking system's RTD.
• Findings are valuable for implementing and optimizing this protocol in continuous bioprocessing applications.
• Understanding tracer dispersion is key to effective virus filter performance evaluation.