Photos: Frozen filtration

Wastewater treatment of the 1920s looks stunning in winter

Constant stream of water in freezing temps created works of art in ice

These images from our archives show trickling filters at their frozen finest. The turn-of-the-century equipment would spray wastewater over large beds of gravel-type media where microbes would remove pollutants. In the winter, these huge beds would freeze the tiny droplets as they sprayed from the nozzles.

This kind of filter is still used today in some cities, including at our Westerly plant in Cleveland, but the process is enclosed from the harsh elements. Its three trickling filters can each handle 35 million gallons of wastewater every day.