A picture is worth 1000 bacteria

  • Paul, Catherine (PI)
  • Gador, Niklas (Forskare)
  • Einarsson, Daniel (Forskare)
  • Mengistu, Dawit (Forskare)
  • Chan, Sandy (Forskare)

Projekt: Forskning



Slow sand filters (SSFs) are a nature-based solution that for hundreds of years have produced safe water for human societies. In Sweden more than 2.5 million people depend on SSFs for drinking water. SSFs use very little energy, no chemicals, generate minimal waste and increase the efficiency of other technologies, so ensuring their optimal function will contribute to achieving multiple UN Sustainability goals.
Microbial biofilm ecosystems living in SFF remove undesirable molecules including organic matter, pathogens and micropollutants. The microbes experience stress due to, for example, flow rate changes, which may increasingly impact SSF in the future. Predicting how SSF will respond to these stresses is difficult, as the genetic and metabolic diversity of the microbes make full scale processes difficult to mimic in the laboratory. In this project, drinking water practitioners, microbiologists, engineers and mathematicians will unite their expertise to explain, and predict, SSF responses at full scale. DNA-based microbial community profiling, water quality data will describe SSFs from across Sweden that experience changes in flow rates, temperatures, weather and source water. These descriptions will be integrated in a mathematical model with which a variety of tests and extrapolations can be made to achieve the following goals: optimize current operation of SSFs; predict changes for the future; and suggest strategies for mitigation and protection of SSF water production.

Populärvetenskaplig beskrivning

Society depends on access to safe drinking water. We consume it every day, as our most important food. We use it when we wash, prepare food, go swimming, fight fires and flush toilets. Hospitals, schools, food processing industries, and farms all depend on access to drinking water for daily operations.
In Sweden, the importance of having safe drinking water as the climate changes has been recognized by many, including the Swedish National Food Agency (press release, February 2, 2018). Severe drought in 2018 triggered media coverage and debates about who has the right to take water, and water restrictions were in place across Sweden. Problems normally associated with far-off places like Cape Town, were suddenly impacting daily life, and this came as a surprise to many, since Sweden is a country that usually has plentiful and easy access to drinking water. This access is due in part to proactive planning. Over 50 years ago, construction began on the 80 km Bolmen tunnel, which continues today to provide source water for expanding agricultural and urban landscapes in Scania. Decisions regarding how to prepare the waterwork processes, however, are also required to meet future challenges including water shortage, fluctuating source water quality, sudden weather events and climate changes. The age of most waterworks in Sweden requires their renewal within the next 10 years and these improvements need to be planned with sustainability and resilience in mind.
More than 2.5 million people in Sweden, from the urban Stockholm to smaller rural communities depend on slow sand filters (SSFs) for their drinking water. SSFs have been used for hundreds of years, and will contribute to sustainable production of drinking water in the future. In SSFs, water passes over the sand using gravity, and bacteria living on the sand remove chemicals, pathogens, toxins, and molecules that make the water smell or taste bad. Removing these molecules also improves the efficiency of other water treatments, such as UV light, and reduces the need for disinfectants such as chlorine. SSFs use very little energy, no chemicals and generate minimal waste and together this means that using SSFs will help Sweden reach its goals to be a bio-based circular economy, reduce greenhouse gases, and create a less toxic environment. With simple construction, SSFs are also used in rural and/or developing communities, and can thus contribute globally to achieving UN Sustainable Development Goal (SDG) 6, dedicated to access to drinking water and sanitation, and other goals linked to access to drinking water, including food security (SDG 2), health and well-being (SDG3), gender equality (SDG5) and sustainable cities (SDG11).
While SSFs are desirable for drinking water production, it is not known how these systems will respond to future challenges. As an ecosystem, microbes in SSF will respond to: changes in, or contamination of, source water; severe weather, temperature rises, and increased demand. We want to understand how the bacteria, and the work they do, will be impacted so we can adapt the SSFs. The waterworks could be modified, or the bacteria could be controlled. The need for understanding is urgent since data must be collected for several years to assess trends, and changes that could protect the SSFs will need time to be tested and adopted by the waterworks.
The good news is that we have many tools to study SSFs. The project team, including drinking water companies and University researchers, has tested new DNA-based methods (flow cytometry and DNA sequencing) and new approaches for handling this data that tell us which bacteria make an SSF work. We see how they change when the environment around them changes. Comparing bacteria in SSFs in Skåne to those in Stockholm can show how temperature effects the ecosystem, while comparing the SSFs in Jönköping to those in Stockholm will show how water demand or different lake source water is important. Using this information, we will build a mathematical model where we can create and test scenarios that are not yet possible to observe. This is essential as microbes do not behave in the same way in real waterworks and in the lab and it is the changes and function of real SSFs that we need to be able to predict. And we need to address these challenges now. The United Nations predicts that the population of Sweden will increase by 2 million people over the next 30 years, with many of them living in the urban centres serviced by the SSFs and their bacteria. We need to know which problems we need to solve while we still have time to solve them.
Gällande start-/slutdatum2019/01/012020/04/30



  • FORMAS, Forskningsrådet för miljö, areella näringar och samhällsbyggande