A blog from University of Borås

Thursday, February 22, 2024

PhD thesis on sustainable denitrification of wastewater

 In a modern wastewater treatment plant, in addition to carbon (named COD and BOD) removal, nitrogen and phosphorus should also be removed. For this purpose, they usually have a denitrification unit. However, the microorganisms need an easily accessible carbon source to be able to remove nitrogen. This carbon source is usually fossil-based methanol or sometimes expensive ethanol.

However, the question is if it is possible to use volatile fatty acids that could be produced from sludge, food wastes etc., and use it as this carbon source? This was the topic for research for Tugba Sapmaz who has nailed her thesis today entitled "Unlocking Sustainability in Wastewater Denitrification through Waste-Derived Volatile Fatty Acids" and will defend it on Friday 15 March 2024. She put these publications in her thesis:

1- Towards maximum value creation from potato protein liquor: Volatile fatty acids production from fungal cultivation effluent

2- Waste-derived volatile fatty acid production and ammonium removal from it by ion exchange process with natural zeolite

3- Potential of food waste-derived volatile fatty acids as alternative carbon source for denitrifying moving bed biofilm reactors

4- The Effect of Sequential and Simultaneous Supplementation of Waste-Derived Volatile Fatty Acids and Methanol as Alternative Carbon Source Blend for Wastewater Denitrification

I wish her good luck with the defense.


Friday, February 2, 2024

Filamentous fungi for fish feed?

 Almost half of the fish we eat are farmed in aquaculture, and to grow the fish we consume more than 100 million tons fish feed. Fish meal is a major protein source of the fish feed, and they capture more than 20 million tons fish for seas and oceans, just to produce fish feed.

Sajjad Karimi worked on his PhD thesis to grow filamentous fungi to produce fish feed with very interesting results. He nailed his thesis today and is defending on 23 Feb. 2023. His PhD thesis is about Filamentous Fungi as a Sustainable Ingredient for Fish Feed, and contains these articles:

1- Evaluation of Nutritional Composition of Pure Filamentous Fungal Biomass as a Novel Ingredient for Fish Feed, Fermentation

2- Dietary Filamentous Fungi and Duration of Feeding Modulates Gut Microbial Composition in Rainbow Trout (Oncorhynchus mykiss)

3- Evaluating the potential of three fungal biomass grown on diluted thin stillage as potential fish feed ingredients

4- Digestibility of the filamentous fungal biomass, Neurospora intermedia, in rainbow trout (Oncorhynchus mykiss)

We wish him good luck during the defense.

Monday, October 31, 2022

PhD thesis: A Fungi-based Biorefinery?

We have many ethanol plants in the world that use grains as raw materials and produce ethanol and animal feed as the products. However, the question is if we can also add lignocellulose materials or fruit wastes, how would it be?  

Gulrü Bulkan worked on this question in 4 years to see if the process can be integrated with fungi and also  organosolv pretreatment to produce ethanol, animal feed, pure lignin and also fish feed and/or human food. She did a lot of techno-economical calculation. 

Gulrü happily nailed her PhD thesis last Friday and will defend it on 18 Nov. 2022. Her thesis title is "Fungi-Based Biorefinery: Valorization of industrial residuals and techno-economic evaluation" and she put these papers in her thesis: 

1- Techno-economic analysis of bioethanol plant by-product valorization: exploring market opportunities with protein-rich fungal biomass production

2- Retrofitting analysis of a biorefinery: Integration of 1st and 2nd generation ethanol through organosolv pretreatment of oat husks and fungal cultivation.  

3- Enhancing or Inhibitory Effect of Fruit or Vegetable Bioactive Compound on Aspergillus niger and A. oryzae

4- Inhibitory and Stimulatory Effects of Fruit Bioactive Compounds on Edible Filamentous Fungi: Potential for Innovative Food Applications

Friday, August 20, 2021

PhD thesis: Pigment and fungiburger from bread and beer wastes?

 Which came first, #bread or #beer? It is a typical question, but doesn't matter for Rebecca Gmoser. She took whatever leftover from bread and also the residual from beer, gave it to an edible filamentous fungus (Neurospora intermedia), and let the fungi grow, so these wastes were converted to a paddy, like a burger with a good taste. In addition, Rebecca was stressed in her work, so she also gave little stress to the fungus to produce very beautiful colours, yellow, orange and red, or we call it natural pigments. Now is the last part of this stressful work, and she nailed her PhD thesis today and will defend on 10 Sep. I wish her good luck with it.

Her PhD thesis was about Circular bioeconomy through valorisation of agro-industrial residues by the edible filamentous fungus Neurospora intermedia.

She also put these publications on her thesis:

1- Filamentous ascomycetes fungi as a source of natural pigments

2- Pigment Production by the Edible Filamentous Fungus Neurospora intermedia

3- Combining submerged and solid state fermentation to convert waste bread into protein and pigment using the edible filamentous fungus N. intermedia

4- From stale bread and brewers spent grain to a new food source using edible filamentous fungi.

5- From surplus bread to burger using filamentous fungi at bakeries: Techno-economical evaluation.

6- Solid-state fermentation of stale bread by an edible fungus in a novel semi-continuous plug-flow bioreactor

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


Wednesday, November 6, 2019

PhD thesis: Biogas or hydrogen from wood and plastics?

Biogas production from food wastes, sludge, or agricultural residuals is easy to produce. The bacteria eat these materials in an oxygen-free vessel and produce biogas or biomethane. But, what to do if the materials are not degradable such as wood or plastics? Our PhD student Konstantinos Chandolias worked on this topic, where the materials first gasified (burned with little oxygen) to produce syngas that is mixture of hydrogen, carbon monoxide and CO2. He gave this syngas to the bacteria to eat it happily and to produce biogas or hydrogen. He studied details of this process, using membrane bioreactors and to develop many technical factors. He nailed his PhD thesis today that is about "Enhanced Methane and Hydrogen production in Reverse Membrane, Bioreactors via Syngas Fermentation" and will defend it on 29 Nov. We wish him good luck.

His thesis had these papers:

1- Rapid bio-methanation of syngas in a reverse membrane bioreactor: Membrane encased microorganisms
2- Syngas Biomethanation in a Semi-Continuous Reverse Membrane Bioreactor (RMBR)
3- Effects of heavy metals and pH on the conversion of biomass to hydrogen via syngas fermentation
4- Protective effect of RMBR against syngas impurities
5- Floating Membrane Bioreactors with,High Gas Hold-Up for Syngas-to-Biomethane Conversion

Friday, October 25, 2019

PhD thesis: Membrane bioreactors for ethanol production

Membrane bioreactors (#MBR) are used so far mainly for wastewater treatment, where the reactors are fed with very diluted wastewater. The MBR provides high concentration of the bacteria to treat the wastewater faster in smaller vessels. However, the question is if we can use this technology to produce biofuels. This was the topic for Amir Mahboubi who developed MBRs for production of ethanol from lignocellulosic materials in his PhD thesis. He developed membrane processes that can handle high concentration of the material, high cell concentration, materials with bacterial contamination or even high inhibitors concentrations, where the process can run continuously in a stable condition. Today, Amir nailed his thesis that is about Immersed flat-sheet membrane bioreactors for lignocellulosic bioethanol production. He will defend his thesis on 18 Nov., and I wish him good luck.

The publications involved in his thesis are:

6-    Concentration-driven reverse membrane bioreactor for diffusion-based fermentation of highly inhibitory lignocellulosic hydrolysate


Thursday, February 21, 2019

PhD thesis: New plates and films from apple pomace and citrus wastes

Do you like orange or apple juice? Do you know while making those juices, half of the apple or orange weight is ended in the wastes? There are some research about these materials to convert it to e.g. ethanol or biogas. On the other hand, there is large global problem with plastics in the world.  Therefore, Veronika Batori tried to produce some replacement for plastics from citrus wastes and apple pomace, and she worked to make new materials and biofilms out of them in her PhD thesis that has title "Fruit wastes to biomaterials: Development of biofilms and 3D objects in a circular economy system". She published several papers is defending her thesis tomorrow. We wish her good luck!

The papers are about:

  1. Production of pectin-cellulose biofilms: A new approach for citrus waste recycling
  2. Synthesis and characterization of maleic anhydride-grafted orange waste for potential use in biocomposites
  3. Anaerobic degradation of bioplastics: a review
  4. The effect of glycerol, sugar and maleic anhydride on the mechanical properties of pectin-cellulose based biofilms produced from orange waste
  5. Development of Bio-Based Films and 3D Objects from Apple Pomace

Sunday, January 6, 2019

Flaring natural gas and producing biogas?

Russia, Iraq, Iran and USA flared (or just burned) natural gas in one year 19.9, 17.8, 17.7 and 9.5 billion m3, respectively. It means these four countries burned 2058 m3 natural gas every second. It results in 127 million tons of CO2 per year that goes to atmosphere and its energy content that is lost is 714 TWh or 61 million tones oil equivalent (mtoe). These numbers can be compared with the total energy production from biofuels and wastes in the world that is ca 132 mtoe after all the efforts in the world. It is a disappointing fact where politicians put political disputes before environmental disasters  and human life.