Biochemical Engineering Flashcards
Anaerobic Baffled (Regulator) Reactor (ABR):
An ABR is designed of several chambers (form 4 to 8); they are separated by Side walls that do not extend all the way.
-For liquid: flows from one chamber to the other by gravity.
-For biomass: settles down.
Up-flow anaerobic sludge blanket Bioreactor (USAB)
-It is a form of anaerobic digester that is used in the treatment of wastewater.
-a methanogenic (methane-producing) digester that evolved from the anaerobic digestion.
-The biomass forms a layer at the bottom of the reactor (the blanket).
Materials for encapsulation
Cellulose nitrate
Cellulose acetate
Nylon
Phospholipids
Sodium alginate
Microbial cells immobilization methods:
- Entrapment
- Bounding
En-trapment
- Matrix entrapment
- Micro-incapsulation
Bounding
- Adsorption
- Covalent bonding
Waste Water Treatment
The process of removing physical, chemical and biological contaminants from waste water.
Purpose of waste water treatment is to reduce BOD and COD
Problems With Current Waste water Treatment Technologies:
- Mixed types of wastes
-Agriculture industry
-Food industry
-Pharmaceutical industry - Power consumption is very expensive
- Aeration is not easy to perform (when the wastes are too thick)
Chemical Oxygen Demand (COD) (mg/L) (water consumes)
Is designed to measure the capacity of water to consume oxygen during the decomposition of organic matter and the oxidation of inorganic chemicals such as ammonia and nitrite
Biochemical oxygen demand (BOD) (Microorganisms):
A parameter used to measure the amount of oxygen that will be consumed by microorganisms during the biological reaction of oxygen with organic material (degradation)
Primary Treatment (organic waste)
Primary treatment removes the materials that can be easily collected from the raw wastewater and disposed off. (Separate liquids from solids, sedimentation so it takes time).
Fats will be floated on the surface and it mechanically removed.
Secondary Treatment (for human waste)
is designed to degrade the biological content of the sewage such as derived from human waste, food waste, soaps , and detergent.
Membrane Biofilm Reactor(MBR)
is the combination of a membrane process like microfiltration or ultrafiltration with a suspended growth bioreactor
-Degrade soluble organic contaminates.
Bioreactor
Any device or system that supports a biologically active environment in controlled conditions. It differs in:
1- Size
2- Material of construction
3- Shape and configuration
4- Heat exchanger
5- Agitation method
Heat exchanger (to maintain the bioprocess at a constant temperature)
-Microbial activities produce metabolic heat.
-Heat can kill those microbes.
-The microbes require low temperature for growth and this problem can be further increased by the friction heat form agitation.
Tertiary treatment (Quality check)
Tertiary treatment provides a final stage to raise the effluent quality before it is discharged to the receiving environment.
-Involves a series of steps to further reduce organic concentration, turbidity, N, P, metals, and pathogens
The organism is grown in a liquid medium vigorously aerated and agitated in large tanks called fermenters.
Submerged cultures fermentation
(attached growth systems)
Microorganisms are grown as a biofilm on a solid growth support matrix.
Stagnant cultures fermentation
Effluent polishing (tertiary)
More than one tertiary treatment process may be used at any treatment plant.
If disinfection is practiced, it is always the final process
Tertiary treatment steps:
- Filtration
-Sand filtration removes suspended matter.
-Filtration over activated carbon removes toxins and odors. - Nutrient removal
-Nitrogen removal
-Phosphorus removal - Disinfection
What are the Precautions?
A biological process requires:
1- Sterility
2- Use of enzymes catalysts
3- Be careful during operation under elevated temperature and pressure
Agitation method
Ensures the proper distribution of substrates, biomass, products and heat.
-Bacterial fermentation requires less agitation than fungal fermentation
Mechanically agitated reactors:
1- Continuous Stirred Tank Reactor (CSTR)
- The standard submerged culture fermenter , the main feature is its motive power, which is a direct mechanical drive
- Used in PHARMACEUTICALS and H2 production.
Types of CSTR:
- Flat-blade turbine (High shearing)
- Marine propeller (for fragile cells)
- Multi-rod impeller
Accessories of CSTR:
- Baffles: to help agitation.
- Spargers and nozzles: to push or diffuse air in (shapes such as a pipe, ring, or spider)
- Propellers
- Foam breaker to prevent foam overflow to condenser.
5 Recycle loops allow separation of the immobilized enzyme from the product.
3 main Non-mechanically agitated reactors
- Liquid agitated reactors
- Gas agitated reactors
- Hybrid Reactors
Liquid agitated reactors:
- Tubular bioreactor (Plug-Flow)
- Membrane (spiral wound bioreactor)
- Packed bed
- Fluidized-bed
- Expanded-bed
- Thin film (fixed film)
- Anaerobic baffled reactor.
- Anaerobic-sludge-blanket.
Gas agitated reactors:
- Air-lift
- Deep jet
- Pressure cycle
eutrophication
A build up of nutrients, which encourage the overgrowth of weeds, algae, and cyanobacteria in water tanks.
An immobilized enzyme
An enzyme that is physically connected to a solid support and is used to transform a substrate into a product.
Immobilization technologies are designed to:
reduce the mobility of contaminants by changing the physical characteristics of the contaminated matrix.
Benefits of Immobilization of enzymes:
-Saves valuable enzymes.
-Protect the enzyme from unfavorable conditions.
-Better process control (the ability to stop the reaction rapidly by removing the enzyme).
-Higher overall efficiency.
-Product is not contaminated with the enzyme.
Major Methods of Enzyme Immobilization:
1-Carrier-Binding
The binding of enzymes to water-insoluble carriers.
Depends on the nature of the enzyme itself, as well as the:
Particle size & Surface area
Major Methods of Enzyme Immobilization:
2- Cross-Linking
is a strategy where enzymes are interconnected through covalent bonding without carriers
Major Methods of Enzyme Immobilization:
3- Entrapping
Involves inserting enzymes into the structure of a semi-permeable gel or enveloping the enzymes in a semi-permeable polymer membrane.
-It is done in such a way as to retain protein(enzymes) while allowing penetration of substrate.
3 Major Methods of Enzyme Immobilization:
1-Carrier-Binding
2-Cross-Linking
3-Entrapping
The carrier binding mode of the enzymes are:
-Physical Adsorption (weak bond)
-Ionic Bond (weak bond)
-Covalent Bond (strong bond)
What is a carrier?
-The support material that holds the enzyme, which may be a matrix, a membrane or a solid support.
-Carrier specifications:
Inert
Durable = withstand
pH effect
Encapsulation
Pore size 100-400
-Using this approach, enzyme leakage can be easily avoided by changing the pore size of the polymeric network, allowing for unrestricted diffusion of either substrates or products.
Advantages of Encapsulation
Loading high capacity of the enzymes, low fabrication costs.
Example of some Methods of Immobilization:
-Adsorption
-Covalent bonding
-Cross linking
-Entrapment
-Encapsulation
Adsorption (Physical)
1-Weak bonding (Hydrogen bonding, ionic bonding, Van Der Waals, Hydrophobic)
2-Easy to do and regenerate.
3-Various material could be used.
Materials used for adsorption
Activated carbon
Silica gel
Alumina
Starch
clay
Cellulose
Resin
Methods of immobilization by adsorption
(physical)
1.The static process.
2. The dynamic batch process.