Text Jeroen van Aken
Safe drinking water
through bacteria
Drinking water from groundwater wells in Bangladesh often has a too high concentration of arsenic. According to estimates, in the worst affected areas one out of 10 adults die from the effects of arsenic poisoning. Engineer Roos Goedhart is researching how bacteria can help remove arsenic in drinking water treatment and as such giving millions of people access to safe drinking water.
Arsenic is considered a heavy metal. It is contained naturally in soil and can end up in groundwater. The long-term ingestion of arsenic raises the chance of contracting cancer. The standard of the World Health Organization (WHO) is that the concentration of arsenic in drinking water may not exceed 10 micrograms per litre.
“The concentration of arsenic in groundwater varies strongly across locations,” says Goedhart. “There are a few places in the Netherlands where the concentration in groundwater is slightly elevated. After purification, the international WHO standard is achieved. Bangladesh and other countries such as Vietnam, India and the United States have locations with more than 100 or even more than 1,500 micrograms per litre.”
In terms of the quality of its drinking water, the Netherlands sets very high goals and continuously invests in treatment. “A better way of removing arsenic from groundwater would both further improve the quality of the drinking water here and make the treatment process more sustainable. Even bigger gains could be made in other countries. In Bangladesh for example, there are still life-threatening quantities of arsenic in drinking water. There are treatment plants, but not all of them work that well.”
‘My goal is to find an alternative for the chemicals and find a natural solution instead of a chemical one’
Groundwater treatment
The basic principle of groundwater treatment in the Netherlands and Bangladesh is similar. The first step is to pump up groundwater and then oxidise it to start chemical reactions. The water is then filtered, often through a container of sand. The water is purified by both chemical and biological reactions in the filter layer. “We still do not know exactly what happens with the arsenic during the treatment process. The process partly removes the arsenic, but the extent to which this is done varies enormously across plants. I am trying to find out why. We want to know which reactions are responsible for arsenic removal and how we can optimise these processes.”
researcher profile
© Universiteitsfonds Delft
Name Roos Goedhart
Expertise Water treatment (Civil Engineering and Geosciences)
Working on better understanding how bacteria remove arsenic during groundwater treatment
Potential applications simple way to make safe, arsenic-free drinking water worldwide
Donation spent on extending the fieldwork and deploying more microbiological expertise
Why TU Delft?
“TU Delft is a recognised entity in water treatment internationally. You see this if you visit other places in the world and we can be very proud of that. I learned everything I know about water treatment at TU Delft, and the laboratory is well equipped to carry out my tests. I will build a small version of a drinking water treatment plant right here in our Waterlab. This enables me to closely track and measure the chemical and biological processes. It is a unique set-up in the Netherlands. This research fits the modern TU Delft well. First understand the problem and access the whole picture, and then start working on a technical solution. In my case I am working on improving water treatment using natural processes with as few interventions as possible.”
Roos Goedhart seeks a natural alternative to chemical purification.
© Roos Goedhart
Natural alternative
At present, if the treatment process does not remove enough arsenic from the water, chemicals are added to optimise this process. “Bangladesh often has small-scale treatment systems. These can lack the manpower, infrastructure and sometimes the chemicals to run this extra purification step. My goal is to find an alternative for the chemicals and find a natural solution instead of a chemical one. This could be used in both the Netherlands and in Bangladesh. We want to find out which bacteria live in these filters and which of them contribute to arsenic removal. The samples of the filters we collect need to be analysed with special microbiological techniques. Some of these are not available at our faculty. With extra budget, I can start applying these techniques myself, and bring this knowledge back to our group. Better analysis ensures more knowledge and a better outcome of the research.”
Safe drinking water
“Water scarcity and contaminated drinking water is an ever increasing issue. Groundwater is a wonderful source of water as it is more protected from external impacts such as pharmaceutical residues and PFAS. But groundwater can be contaminated with toxic arsenic, which has to be removed. If we can find a simple solution for this, there will be a lot more safe drinking water available.”
Extend fieldwork
“In Bangladesh we have measured different types of filters in water treatment plants to monitor arsenic removal. Additional budget will help us extend the fieldwork, also to other countries. This will help us gain understanding in the processes in different parts of the world, making our research even more relevant.”