A blog from University of Borås

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.

Thursday, September 6, 2018

PhD Thesis: Fungal-based biorefinery for food industries

Starch is a major component of our food and even materials. There are a number of companies in the world that produce starch from e.g. potato and wheat. However, the residuals of the potato and wheat ends up in dirty wastewater that is not so easy to treat by wastewater treatment plants; and the companies have to pay a lot of money to get rid of it. Now, the question is if we can convert these waste and wastewater into something useful? 

It was the topic of PhD thesis of our PhD candidate Pedro Ferreira de Souza Filho. He worked on converting these types of wastes to fungi for animal feed and also some kind of bioplastic materials. He has now nailed his thesis and will defend it in 3 weeks. I wish him good luck. Here is his PhD thesis on “Fungi-based biorefinery model for food industry waste: Progress toward a circular economy“. He has also published these articles:

Friday, March 16, 2018

PhD Thesis on textile-based bioreactors

There are millions of bioreactors in the world for production of ethanol, biogas, antibiotics, lactic acid and other materials. These bioreactors are principally some tanks with some control equipment that should be tight, tolerate all the chemicals and microorganisms inside and the conditions and weather outside and also the pressure of the liquid. These bioreactors are normally made of stainless steel. However, the question is if we can make it of textile that could be cheaper and movable?

It is now many years that we are working with a company to develop such bioreactors. They look like a big bag, but actually not! Alex Osagie Osadolor has worked for 4 years to consider the design aspects of such textile-based bioreactors for production of biogas, ethanol and fungi. The questions are for example the pressure that the liquid and gas can put on the reactor material, or the mixing and movement of the materials inside it!

Alex has nailed his PhD thesis yesterday and will defend it on 6 April. We wish him good luck!

Here is the link to his thesis of "Design and Development of a Novel Textile-based Bioreactor: Ethanol and biogas production as case studies" that include these papers:

1- Introducing textiles as material of construction of ethanol bioreactors

2- Development of novel textile bioreactor for anaerobic utilization of flocculating yeast for ethanol production

3- Membrane stress analysis of collapsible tanks and bioreactors

4- Empirical and experimental determination of the kinetics of pellet growth in filamentous fungi: A case study using Neurospora intermedia

5- Cost effective dry anaerobic digestion in textile bioreactors

6- Effect of media rheology and bioreactor hydrodynamics on filamentous fungi fermentation of lignocellulosic and starch-based substrates under pseudoplastic flow conditions

Friday, November 10, 2017

PhD thesis on Dry Digesion

We have millions of biogas reactors in the world to take care of wastes (manures, food wastes, swage sludge, etc.) to produce biogas or biomethane. Circa 90% of the materials inside these digesters is water and the rest is the solid materials. It is a good technology, but contain a lot of water and produce a lot of wastewater. On the other hand, a more common and cheap method to take care of the wastes in the world is landfill. Landfills produce gas that contain ca 50% methane and is a source of greenhouse gases (GHGs) in the world. Nobody likes landfill (probably except the owners who make money), but it is still common. So, the question is if we can use the advantages of landfills and biogas?

The answer is in the PhD thesis by Regina Patinvoh who worked on "Biological Pretreatment and Dry Digestion Processes for Biogas Production", so she developed a batch dry digestion (as a cost-effective method) and continuous dry digestion (as more advanced method). She also worked with materials that difficult to digest such as chicken feathers and citrus wastes by this method. She nailed her thesis today and will defend it now on 1 Dec. 2017. I wish her good luck!

Here is the scientific articles as part of her thesis:

1- Biological pretreatment of chicken feather and biogas production from total broth

2- Dry fermentation of manure with straw in continuous plug flow reactor: Reactor development and process stability at different loading rates

3- Innovative pretreatment strategies for biogas production

4- Cost effective dry anaerobic digestion in textile bioreactors: Experimental and economic evaluation

5- Biogas digesters: from plastics and bricks to textile bioreactor—A review

6- Dry anaerobic co-digestion of citrus wastes with keratin-rich and lignocellulosic solid organic wastes: Batch vs. Continuous Process

Thursday, September 14, 2017

PhD Thesis: Integration of first and second generation bioethanol processes

Ramkumar Nair has nailed his PhD thesis happily today. He worked four years on the concept of integrating lignocellulosic materials into the first generation ethanol using filamentous fungi. Considering 4 decades development of lignocellulosic ethanol (called 2nd generation ethanol), this process still has economical challenges to come into the market, particularly with current low oil price. On the other hand, we have many ethanol plants producing from sugar and grains, named 1st generation ethanol. So, our idea is to integrate these processes in order to make 1st generation ethanol plants to produce lignocellulosic ethanol. Ram has done great job in this line and we hope to see soon the results in large scales. But, first we wish him good luck for his PhD defense on 6 Oct. Here is his PhD thesis, including these articles:

1-  Dilute phosphoric acid pretreatment of wheat bran for enzymatichydrolysis and subsequent ethanol production by edible fungi Neurosporaintermedia

2- Optimizing dilute phosphoric acid pretreatment of wheat straw in thelaboratory and in a demonstration plant for ethanol and edible fungal biomassproduction using Neurospora intermedia

3- Integrated process for ethanol, biogas and edible filamentous fungi basedanimal feed production from dilute phosphoric acid pretreated wheat straw

4- Mild-temperature dilute-acid pretreatment of lignocelluloses for ethanolproduction using filamentous ascomycetes fungus, Neurospora intermedia

5- Mycelial pellet formation by edible ascomycete filamentous fungiNeurospora intermedia