Mauricio Barreto Carvajal earns PhD for research to adapt sanitation bioreactors for use in refugee camps
Mauricio Barreto Carvajal from Colombia successfully defended his PhD thesis and was awarded a doctoral degree on 21 December 2023. His promotor was Professor Damir Brdjanovic and his co-promotor Dr. Hector Garcia Hernandez. Dr. Barreto Carvajal shares a few insights as he embarks on a new chapter of his life.
My thesis in a nutshell
My research, financed by the Bill and Melinda Gates Foundation, is about wastewater treatment (sanitation) - how you treat the water before you discharge it into the environment, so that it does not pollute or cause a public health risk. My research focuses on a wastewater treatment method using membrane bioreactors (MBRs). In wastewater treatment MBR treatment is the smallest option: the space required is smaller than that required by other systems. Still, the smaller the better, particularly for use in refugee camps, where you need compact and portable solutions.
My research aimed to minimize the footprint and volume of an MBR. As a consequence of the reduction in size, the biomass concentration of the wastewater increases, and a series of operational limitations compromise the ability to treat wastewater in an effective and efficient way. I had to tackle these limitations, or technical barriers: the oxygen transfer and the permeate flow reduction through the ultrafiltration membrane. I developed an alternative method for transferring pure oxygen into activated sludge with very high biomass concentrations and an alternative process configuration to reduce membrane fouling.
This method can be used to meet emergency sanitation needs, and it can be used in small towns that need decentralized sanitation.
Memorable moments
At the beginning of my research, I had several occasions when I arrived at the pilot setup at the wastewater treatment plant in the Harnaschpolder and found an empty bioreactor and its entire contents – 1,000 liter of concentrated activated sludge - spilled all over the floor. I had to do a lot of cleaning! I will never forget dealing with full size sludge pumps and frozen pipes in winter, or being inside the bioreactor to fix something.
Challenges during my PhD
I had a lot of fun, but I also faced some periods with low motivation, which was difficult. In my third year, I had a burn-out. Then I did not have the energy and motivation to focus on my research. However, eventually I recovered.
The influence of my PhD research
This method can be used to meet emergency sanitation needs, and it can be used in small towns that need decentralized sanitation. The method prevents environmental pollution of water sources, and it makes it possible to treat a lot more water for less money.
Future plans
I am currently working with the United Nations in Ukraine on water and sanitation projects in the humanitarian sector and I will continue to work on these projects.
An important lesson
I would manage my expectations, seek better financial conditions and prepare myself mentally that a PhD is demanding. I would also have liked to do some of the experimental work in my home country, Colombia.