Biofilm in Water Utilities

Biofilms have been used for treating drinking water for more than 200 years, but we still don’t know much about how biofilms work. This project is using DNA sequencing and flow cytometry to increase knowledge and better understand the role of biofilms in effective, safe drinking water production.

Biofilters have been used to treat drinking water for over 200 years. Despite their long history, little is known about these filters. Water is pumped on top of a biofilter and is slowly passing through the media. On the media, e.g. sand, there is a biofilm with a living community of microorganisms capable to remove both chemical contaminants and harmful microbes (bacteria, protozoa and virus).

Infiltration ponds at Vombverket and slow sand filters at Ringsjöverket are examples of biofilters. The purpose of this project is to investigate the biofilm in these two processes. Using massively parallel DNA-sequencing, the effect of different source waters on the biofilm community in an infiltration pond at Vombverket has been investigated. To further gain better understanding about biofilters, the bacterial community in influent and effluent waters from slow sand filters at Ringsjöverket have been studied with DNA-based flow cytometry using cytometric analysis tool.

Traditional methods to analyze bacteria in drinking water involves cultivation which is time-consuming and can only resolve a small part of the total bacteria community. In contrast, flow cytometry is able to count all bacteria in the water and determine if the bacteria are alive or dead. This method together with DNA-sequencing gives us the possibility to follow slow sand filters and investigate the bacterial community within these filters. In the future, with better understanding and analysis techniques, the goal to optimize and control biofilters can be achieved for a better drinking water production.