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Particles in a solid are tightly packed together (fixed shape) and often arranged in a regular pattern; in a liquid, they are close together with no regular arrangement (no fixed shape); in a gas, they are far apart with no regular arrangement (no fixed shape). Particles in a solid vibrate about fixed positions (cannot flow) and do not generally move in relation to one another; in a liquid, they move past each other (can flow) but remain in essentially constant contact; in a gas, they move...
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The speed of sound in a gaseous medium depends on various factors. Since gases constitute molecules that are free to move, they are highly compressible. Hence, sound waves travel slowly through gases. Thermodynamics helps us understand the relationship between pressure, volume, and temperature of gases, thus, the speed of sound in an ideal gas can be determined using the laws of thermodynamics. At the same time, Newton's laws of motion and the continuity equation of fluid dynamics also come...
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Microalgae Cultivation and Biomass Quantification in a Bench-Scale Photobioreactor with Corrosive Flue Gases
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Effective bioreactor pH control using only sparging gases.

Linda Hoshan1, Rubin Jiang1, Joseph Moroney1

  • 1Biologics Process Research & Development, Process Research & Development, Merck & Co., Inc., Kenilworth, New Jersey 07033.

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|November 14, 2018
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Summary
This summary is machine-generated.

This study shows that controlling bioreactor pH using air sparging, instead of base addition, maintains stable conditions for Chinese hamster ovary (CHO) cell cultures. This method is scalable for industrial bioprocessing.

Keywords:
CO2 removalChinese hamster ovaryammoniumlactatemammalian cell cultureprocess control

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Area of Science:

  • Biotechnology
  • Biochemical Engineering
  • Cell Culture Technology

Background:

  • pH control is crucial for bioreactor performance, often relying on CO2 sparging and base addition.
  • Base addition can negatively impact cell culture by increasing osmolality and causing pH excursions, especially in large-scale operations.

Purpose of the Study:

  • To assess the feasibility of using sparge gas composition control for pH regulation in Chinese hamster ovary (CHO) fed-batch cultures.
  • To evaluate fine pH control strategies in small-scale bioreactors and demonstrate scalability.

Main Methods:

  • Implemented a feedback control loop adjusting air sparge composition for pH regulation.
  • Conducted experiments in ambr®250 bioreactors with Chinese hamster ovary (CHO) cells at various pH setpoints.
  • Validated the control strategy's effectiveness and scalability from benchtop (ambr®250) to pilot scale (200 L).

Main Results:

  • Successfully maintained desired culture pH setpoints using air sparge feedback control.
  • Demonstrated that increased air sparging effectively removes CO2, thereby increasing culture pH, and vice versa.
  • Confirmed the seamless transferability and scalability of the air sparge control method.

Conclusions:

  • Controlling sparge gas composition is a viable alternative to base addition for pH control in bioreactors.
  • This air sparge strategy offers precise pH management and is scalable for industrial bioprocessing, potentially improving culture performance.