Evaluation of a sand filter material for road runoff treatment– Pilot-scale field trial focused on copper and zinc removal

• The negative effects of stormwater discharges on receiving aquatic environments and the need for their purification were highlighted by the EU courts' "Weser-Ruling" in May 2020. The ruling stated the need for removal of dissolved pollutants. The decision justifies field studies for development of far-reaching methods for runoff treatment. In this in situ study, a standard sand was used as medium for road runoff filtration and removal of dissolved and particle-bound (< 0.45 µm) zinc (Zn) and copper (Cu), Data collected included 24 road runoff events, mimicking the flow variations and pollutant emissions over a seven-month period. The findings showed that filter sand can be used to remove Zn and Cu from road runoff in a gravity fed treatment system. The removal of total Zn and Cu was 93% and 67%, respectively. Dissolved Zn was efficiently removed by the sand (87%), however not Cu (19%). The sand efficiently removed total suspended solids (TSS) from maximum occurring 443 mg L-1 to below 5 mg L-1. No head loss due to the TSS loadings was observed. The initial studies show the sand's potential to remove the investigated metals, but in the longer term, effluent concentrations may exceed emission permit values.

Nyckelord

Road runoff

metals

column experiment

sand filter

Land and Water Resources Engineering

Mark- och vattenteknik

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)