Removal of metals and hydrocarbons from urban snowmelt by coagulation and flocculation

• The treatment efficiency of a coagulation/flocculation and sedimentation process was investigated in urban snowmelt. Five different coagulants were evaluated for their effectiveness in reduction of particle content, organic carbon, total and dissolved metals, hydrocarbon oil index, PAHs and if any changes occurred in the particle size distribution. The pollutants in the snow melt were mostly in the particulate phase, and for both oil index and PAHs characterized by the larger sized molecules. An iron chloride coagulant was the only coagulant that had an effect on the particle size distribution post-treatment, where the distribution was shifted towards larger particles. In terms of total metal removal, the performance for the coagulants were similar with above 90% removal on average. Dissolved Cu, was one of the metals found in the dissolved phase, and it was reduced by 40% by coagulation treatment. The iron chloride coagulant did increase the dissolved Zn, attributed to a larger drop in pH resulting in a higher ion mobility. Similarly, the reduction in organic content, both TOC/oil/PAH were above 90% for most coagulants.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Samhällsbyggnadsteknik -- Vattenteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Civil Engineering -- Water Engineering (hsv//eng)

Keyword

Stormwater treatment

pollutant removal

treatment efficiency

VA-teknik

Urban Water Engineering

Publication and Content Type

vet (subject category)

ovr (subject category)