By: European Commission DG Environment

Tall sedge in biofiltration systems removes the majority of dissolved phosphorus from greywater

Excess phosphorus from agricultural, industrial or urban sources is an environmental pollutant, which can cause euthrophication, oxygen depletion and biodiversity loss in waterways. A biofiltration system — a technology that uses sand or planted soil to filter pollutants — is used to remove phosphorus and other nutrients from water before it is released into rivers or other waterways. Originally used to treat stormwater run-off, biofiltration systems are increasingly used to treat polluted water such as greywater (i.e. non-sewage waste water from baths, sinks, washing and other domestic sources) and partially treated waste water from urban areas. However, the fate of dissolved phosphorus within biofilters is not well known. For example, it may be taken up by plants or deposited within the sand; more accurate information may help improve the efficiency of phosphorus removal within biofiltration systems.

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This study examined the separation of dissolved phosphorus within a biofilter using a phosphorus radiotracer to see where dissolved phosphorus was stored. A radiotracer is a chemical compound with the addition of a radioisotope, which can be used to map where a compound travels within a living system.

Source: Fowdar, H.S., Hatt, B.E., Cresswell, T., Harrison, J.J., Cook, P.L.M., Deletic, A. (2017). Phosphorus Fate and Dynamics in Greywater Biofiltration Systems. Environmental Science &
Technology, 51:2280–2287. DOI:10.1021/acs.est.6b04181.