Unveiling the microbial dynamics and hidden potential of slow sand filters

Slow sand filters are one of the oldest and most sustainable methods for producing safe drinking water. They work not only by removing particles but also thanks to the activity of diverse microbial communities that live in the sand. However, how these microbes develop, adapt, and recover after disturbances has not been fully understood. In my PhD research, I studied the microbial life inside full-scale and pilot-scale slow sand filters in Dutch drinking water plants. I investigated how factors such as the quality of incoming water, nutrient availability, and filter maintenance influence microbial communities and their role in water purification. My findings show that these communities are resilient, adapt quickly to changing conditions, and play a key role in ensuring biologically stable, safe drinking water. This work improves our ecological understanding of slow sand filters and supports their optimisation for future water treatment challenges.