Gnistängstunneln, tunnel wash water

Treatment feasibility study of tunnel wash water and design of a treatment system capable of treating all tunnel wash water in Gothenburg.

Treatment of tunnel wash water

Utilizing Swedish Hydro Solutions chitosan and BioMedia treatment, suspended sediment was reduced from 13 000 mg/l to <1 mg/l after treatment. The removal efficiency for heavy metals was 96-99 % and for organic contaminants 93-99,9 %

Treatment results

Suspended material, mg/l

  • Guideline value, City of Gothenburg (25 mg/l)
  • Untreated water (13 000 mg/l)
  • After chitosan treatment (24 mg/l)
  • After chitosan + BioMedia ( <1 mg/l )


  • Guideline value, City of Gothenburg (0.05 µg/l)
  • Mercury in untreated water(0,11 µg/l)
  • After chitosan treatment (0,0041 µg/l)
  • After chitosan + BioMedia (<0,002 µg/l)


  • Guideline value, City of Gothenburg (0,05 µg/l)
  • Untreated water (2,2 µg/l)
  • After chitosan treatment (< 0,01 µg/l)
  • After chitosan + BioMedia (<0,01 µg/l)

Need more information?

Carl-William Kalholm - sales coordinator

+46 723 05 80 85

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