A blog from University of Borås

Tuesday, October 20, 2020

PhD thesis: Methane and Volatile Fatty Acid Production from Toxic Substrates

 In a previous thesis, we showed how to produce volatile fatty acids (VFAs) from food wastes. However, what to do if the material are toxic such as citrus wastes? Lukitawesa worked with two toxic materials including #citrus_wastes and #patchouli wastes. Both of these materials contain flavours that kill the bacteria in methane production. So Luki tried to protect the bacteria using hydrophilic membranes or use the self defence mechanism in granules where the bacteria support each other in #biogas production. Then, the question is if these toxic materials kills #methane producing bacteria, why not turn the problem to an opportunity and to produce VFAs instead of methane? So, it took him several years to succeed in producing also the VFAs and hopefully a PhD for himself as well. He nailed his thesis now and will defend it on 30 Oct. His defence can be followed live on this link on Zoom or this link on YouTube.

Here is his thesis:

Methane and Volatile Fatty Acid Production from Toxic Substrates

including these articles:

1- Inhibition of patchouli oil for anaerobic digestion and enhancement in methane production using reverse membrane bioreactors

2- Semi-continuous reverse membrane bioreactor in two-stage anaerobic digestion of citrus waste

3- Effect of effluent recirculation on biogas production using two-stage anaerobic digestion of citrus waste

4- Factors influencing volatile fatty acids production from food wastes via anaerobic digestion

5- Effect of pH, substrate loading, oxygen and methanogens inhibitors on volatile fatty acid production from citrus waste by anaerobic digestion

6- Semi-continuous Production of Volatile Fatty Acids from Citrus Waste using Membrane Bioreactors

Wednesday, September 16, 2020

PhD thesis: Food waste-based volatile fatty acids using membrane bioreactors

Do you know we have ca 200 kg food loss and waste in the world "per person" each year? It is a huge amounts of materials are the wasted and end up in dumping areas and landfills, or in the best case, it is converted to compost or biogas. Landfill is terrible in environmental point of view and compost and biogas have economical challenges. Therefore, since several years ago we tried to develop #anaerobic_digestion to produce #Volatile_Fatty_Acids or #VFAs instead of #biogas. Our PhD candidate Steven Wainaina has developed a system of #membrane_bioreactor to avoid biogas production and produce VFAs continuously at high concentration from food wastes. It was a real development with high potential to commercialise the process. However, the 2nd question is what to do with VFAs? VFAs is a platform material that can be converted to many other products such as bioplastics. However, Steven produced fungi from VFAs that can be used for animal feed. It means with this work, we can covert food wastes to animal feed in a correct way. Steven nails his PhD thesis two weeks ago and is defending it now on Friday and can be followed at YouTube. I wish him good luck!

Here is the thesis title:

Developing a food waste-based volatile fatty acids platform using an immersed membrane bioreactor

and it contains several publications: 

1- Food waste-derived volatile fatty acids platform using an immersed membrane bioreactor

2- Bioengineering of anaerobic digestion for volatile fatty acids, hydrogen or methane production: A critical review

3- Anaerobic digestion of food waste to volatile fatty acids and hydrogen at high organic loading rates in immersed membrane bioreactors

4- Utilization of food waste-derived volatile fatty acids for production of edible Rhizopus oligosporus fungal biomass