Biotechnological Conversion Processes
Biofuels, Microbial fuel cells, microalgae technology (cultivation, oil production), Biofuels from Agricultural Wastes and By-Products
Biofuels, Microbial fuel cells, microalgae technology (cultivation, oil production), Biofuels from Agricultural Wastes and By-Products
Fichier Détails
| Cartes-fiches | 149 |
|---|---|
| Langue | English |
| Catégorie | Technique |
| Niveau | Université |
| Crée / Actualisé | 06.02.2022 / 11.02.2022 |
| Lien de web |
https://card2brain.ch/box/20220206_biotechnological_conversion_processes
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What is the characteristic concentration curve for the compartment model when applying the dye experiment?
See pic
Please show in a diagram the substrate concentration and the product concentration.
See pic
How does the concentration curve for the mixed reactor look like when applying the dye experiment? How does it change if we consider the mixed reactor to have a dead volume?
See picture
-> change if we consider the mixed reactor to have a dead volume:
Higher start concentration (as the dye gets less diluted) and a longer tail.
What methane concentration (within the biogas) is needed for Combined Heat and Power (CHP)?
45% and above
Which upgrading processes are necessary to feed biogas in the national gas grid?
Which are examples of drying processes?
ToDo Is biogas technology a green technology?
ToDo
Depends...
Which parameters influence the carbon footprint of a biogas process?
The major contributors to carbon footprints are: transportation of biomass
… and “bioreactor household energy” ?
Renewable Substrate: Cultivation, Storage, Transport
> CO2: Diesel Engines
> N2O: Renewable cultivation
Biogas Production
> CO2: Process Electricity
> CH4: Open Digestate Storage & Leakage
Biogas Usage in a Cogeneration Unit
> CO2: Process Electricity
> CH4: Not completely burned methane
Sufficient? ToDo?
What are the main steps to convert microalgae to biodiesel?
Production of microalgae biofuels:
1– Algae strain selection
2– Identification of optimum growth culture conditions
3– Effective microalgae cultivation systems, harvesting, and separation of algae biomass
4– Extraction of fatty acids and lipids (Drying → Solvent for lipids)
5– Conversion: Transesterification → Algae lipids → FAME
Describe advantages of biodiesel production of microalgae?
• Advantages of microalgae:
– Fast growing and produce high amounts of lipids and carbohydrates
– Less demand for water and requirement of non-arable land
– Biomass production exceed terrestrial crops and trees
– All year around production
– Oil yield is constant as compared to oilseed crops
– No need for pesticides or herbicides
– Eliminate CO2 from flue gasses emitted from fossil fuels
– 50-70% of lipid/oil content on dry weight
Define Syngas Fermentation Process? Which products can be derived from the intermediate formed in the process?
• Syngas fermentation is a hybrid thermochemical/ biochemical process that takes advantage of the gasification process and the specificity of the fermentation process.
• Energy-rich biomass and waste materials are converted by gasification to syngas (mainly CO, H2 and CO2). These gasses are then converted to ethanol and other chemicals by acetogenic microbes.
• The main products of syngas fermentation include ethanol, butanol, acetic acid, and methane.
Which is the most common reactor type for synthesis gas fermentation?
CSTR = Continuous stirred-tank reactor
• In literature, a CSTR is often named the most common reactor type for
synthesis gas fermentation.
• The simplest alternatives are bubble columns or gas lift reactors.
Mention at least 3 important factors that influence Biofiltration.
● Filter media
○ Compost
○ Soil
○ GAC (Granulated Activated Carbon)
● Microorganisms
● Moisture Content
● Temperature
● pH
● Pressure drop
● Waste stream composition
What are some advantages of the Biofiltration process?
● Low operation, capital, and maintenance cost
● Easy operation and startup
● High gas/liquid surface area
● Does not need high energy inputs or chemical reagents
● Avoids secondary pollution
Explain how the drying process "Membrane process" works.
Different Permeabilities of water and methane. There is also an additional separation of other unwanted components.
Explain how the drying process "Drying with triethylenglycol" works.
Absorption in a hygroscopic (tending to absorb moisture from a solution) TEG-solution
Explain how the drying process "Drying with silica gel" works.
Silica gel dries by adsorption, which means that the water molecules adhere to the surface of the silica gel.
Explain how the drying process "Cooling process" works.
Water condenses out of the gaseous phase. See picture
Dry cooling removes heat from a system using sensible heat rejection.
Process Models – Mode of Operation:
Give examples of enrichment processes.
> Pressure Water Scrubber
> Gas scrubber
> Pressure Swing Adsorption
> Membrane Processes
Explain how the "Pressure Swing Adsorption" enrichment (of methane) method works.
PSA is based on the phenomenon that under high pressure, gases tend to be trapped onto solid surfaces, i.e., to be "adsorbed". The higher the pressure, the more gas is adsorbed. When the pressure is dropped, the gas is released, or desorbed.
What are the advantages of the "Pressure Swing Adsorption" enrichment (of methane) method?
What are the disadvantages of the "Pressure Swing Adsorption" enrichment (of methane) method?
What are technical options to prevent high concentrations of H2S in biogas plants?
1. Injection of air (biological)
2. Addition of ironsalts (precipitation)
3. Activated carbon (adsorption)
4. Gas scrubbing (biological)
What are Types of Wet Bioreactors?
What does DOC stand for?
Dissolved Organic Carbon
Explain the Concept of Thermal Pretreatment of Biogas Substrates.
See pic
What mechanical Pretreatment of Substrates exist?
• Shear stress
• Bouncing
• Pressure
What thermal Pretreatment of Substrates exist?
• Hot Water
• Steam
• Hydrothermal Hydrolysis
What chemical Pretreatment of Substrates exist?
• Acid
• Alkaline
• Oxidation
What biological Pretreatment of Substrates exist?
• Enzymes
Pretreatment of the Substrate – Ensilagening of Maize
Why ensiling?
conservation of the substrate
Pretreatment of the Substrate – Ensilagening of Maize
What happens on the microbial level?
> production of lactic acid by lactid acid bacteria
> reduction of the pH-Level (3,4-5,0)
Pretreatment of the Substrate – Ensilagening of Maize
Realization on a technical level?
...different types and techniques of silos...
The process of silage making includes cutting fresh (green) fodder, compacting it, and storing and fermenting it under controlled conditions in a silo, where air cannot come in contact with the silage.
What are approaches to technical prevention of inhibition by tensides?
• Keep concentration below a certain level, depending on the Tenside
• Dilution
• Neutralisation
What are approaches to technical prevention of inhibition by heavy metals?
Precipitaion as carbonate or sulfide
What is the source of Tensides?
• Cleaning processes
Why are tensides in the culture broth undesirable?
• Inhibition of the process (decrasing pH)
• Destroying biological membranes
What is the source of Antibiotics and Mycotoxins? And why are they undesirable?
• Inhibition at low concentrations (0,15 - 1 g/kg)
> sources:
• Veterinary medicine
• Manure
• Animals remains
• Grain (mycotoxins)
What are approaches to technical battle the inhibition by Antibiotics and Mycotoxins?
Dilution
