Overview of bioreactor or fermenters

Overview of bioreactor or fermenters

Contents

  • Introduction
  • History
  • Function
  • Design
  • Classifications

Introduction

  • It is a device or system that used to support biologically active environment.
  • It is a system within which substrate of very low value is employ by living cells or enzymes to produce a product of greater value.
  • A fermenter is a closed system vessel which have an adequate provision for temperature, agitation, aeration, pH control, and drain or overflow vent to remove waste biomass of culture microorganism with their products.

History

  • In 1944 De becze and Liebmann used the primary large-scale fermenter for the growth of yeast.
  • But, during the time of world war there’s is a British scientist whose name is Chain Weizmann who desigined a fermenter for the production of acetone.

Functions

  • It should have a provision to control environment for optimum biomass or product yield.
  • It should provide an aseptic fermentation condition for more reliablity.
  • It should provide the adequate or proper mixing and aeration for the growth and production without damaging of the microorganisms or cells.
  • It should have a system temperature control.
  • It should have a system to monitor and regulate pH of the fermentation broth.
  • Facility for sampling should be provided.
  • It should have required minimum of labour in maintenance, cleaning, operating and harvesting operation.

Design

A bioreactor should consist of the followings:

  1. Agitation- for mixing of cells and medium.
  2. Aeration – aerobic fermentation used for oxygen supply.
  3. Temperature
  4. pH, pressure, nutrients feeding, etc.
  5. Sterilization and maintenance of sterility.
  6. Withdrawal of cells or media.

Agitation and Aeration

  • Agitations are aims to ensure similar distribution of microorganisms and the nutrients in the broth.
  • Aeration to provide microorganisms growing in submerged culture with adequate oxygen supply.

The following components of the fermenter which is required for aeration and agitation:

  1. Agitator (impellers)
  2. Stirrer glands and bearings
  3. Baffles
  4. Sparger (the Aeration system)

Agitator (Impellers)

  • It is of several different type:
    1. Disc turbine
    2. Vaned disc turbine
    3. Open turbine
    4. Propeller
  • It achieves the following objective:
    1. Bulk mixing
    2. Air dispersion
    3. Oxygen transfer
    4. Heat transfer
    5. Maintain uniform environment

Stirrer glands and bearings

  • It provides for maintaining aseptic conditions over a long period.

Four basic types of seals used in fermenters are:

    1. Stuffing box
    2. Simple bush seal
    3. Mechanical seal
    4. Magnetic drive

Baffles

  • It is metal strips.
  • One tenth of the vessels diameter.
  • Attached radially to fermenters wall.
  • It provided to prevent vortex formation and improve efficiency.

Aeration system (Sparger)

  • It introduces air into the fermenters broth.

It is of three types:

    1. Porous Sparger
    2. Orifice Sparger
    3. Nozzle Sparger

Temperature control: adequate provision for control of Temperature.

Pressure gauge: It measures pressure inside the fermenters.

pH probe: It provides to measure and monitor pH of the medium.

Inlet air filter: Provision to supply air in the fermenters.

Exhaust air filter: Provision to drain out the air from the fermenters.

Cooling jacket: Provided to maintain the temperature of the fermenters throughout the process.

Control panel: it monitors all the parameters.

Foam control: it is produced during most microbial fermentation. Antifoams are used to removes foam from the surface of media e.g., silicone, soybean oil, cotton seed oil, sulphonate etc.

Classifications

  • On the basis of agent used, bioreactors are of two types:
    1. On the basis of living cells
    2. On the basis of enzymes employed
  • In the terms of process fermenters, is of following types:
    1. Aerobic
    2. Anaerobic
    3. Solid state
    4. Immobilized cell disruption

Types of fermenters

  • Fermenters are of 4 types:
    1. Stirred tank reactor
    2. Airlift fermenters
    3. Tower fermenters
    4. Bubble up fermenters

Stirred tank reactor

  • Smaller vessel is made up of glass while, lager vessels are made up of stainless steel of 1-1,000 or even 8,000L.
  • They are closed system in which volumes are fixed.
  • They are agitated with motor driven stirrer’s.
  • It is a kind reactor with continuous flow culture system which is either of chemostat or turbidostat type.

Airlift fermenters

  • It comprises of a gas light baffled riser tube or drought tube which is connected to the downcomer tube.

It is of two types:

    1. Internal- loop airlift bioreactor
    2. External loop airlift bioreactor
  • These type of fermenters are commonly employed for aerobic bioprocessing technology.
  • Because of their high efficiency, it is mostly preferred for production of methanol and SCP, etc.

Tower fermentation

  • It was defined by Greenshields and co-workers.
  • It is an elongated non-mechanically type of fermenters.
  • There is unidirectional gases flow throughout the bioreactors.

Tower fermenters are of following types:

    1. Bubble columns
    2. Vertical tower beer fermenters
    3. Multistage fermenters

Bubble up fermenters

  • It is a bubble columns fermenters which havee an internal cooling coil.
  • Air is introduced from the bottom of the column.

Reference and Sources

  • 1% – https://wiki2.org/en/Bioreactor
  • 1% – https://samacheerkalvi.guru/author/bhagya/page/9/
  • 4% – https://www.slideshare.net/shmpanwar92/bioreactors-fermenters-56475754
  • 2% – https://senthilarivan.wordpress.com/2015/11/26/fermenter-and-its-features/
  • 1% – https://www.dedot.info/airlift-fermenters-17/

Overview of bioreactor or fermenters

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