A river emits five times more methane with treated wastewater

Nov. 15 () –

A stretch of river into which treated wastewater is discharged emits five times more methane than a stretch of river without that wastewater.

This is confirmed by the research of Ida Peterse and Lisanne Hendriks, from Radboud University, whose findings are published in the journal Science of The Total Environment.

For the study, microbiologist Peterse and ecologist Hendriks measured methane emissions at different points in the Linge and Kromme Rijn rivers, in the Netherlands.

Peterse explains in a statement: “We used a floating camera to capture the gases rising from the river on the water surface and analyze them. We also investigated what nutrients were in the water and soil.”

The researchers carried out this study 500 meters before a water treatment plant, at the discharge point of the treatment plant itself, 500 meters after it and so on up to two kilometers later. “Two kilometers after the discharge point of a treatment plant, we observed a peak of methane emissions, up to five times higher than at the discharge point itself.”

Researchers show that treated water, even if it is clean by Dutch standardshas effects on the river.

Hendriks says: “Treated water also contains nitrogen, phosphate and carbon. All those nutrients in the water cause more algae to grow, for example. They die and sink to the bottom, which in turn is an ideal situation for methane-producing microorganisms.

Because this process takes time, methane emissions are not much higher just after a spill point. However, a little later they are.

Peterse adds: “Although water discharged into rivers meets Dutch standards, it is important to realize that it still contributes to higher methane emissions. Given that water systems such as rivers are responsible for 50% of methane emissions, “This is something we could address.”