The HIAS Process: Next generation biological nutrient removal: PRESENTATION ONLY

Saltnes, T. and Øfsti, A.T., Hias How20 AS, Norway


The moving bed biofilm reactor (MBBR) was invented in Norway in the late 80’s and is today a widespread mature technology for removal of nitrogen and organic matter (Ødegaard et al, 1994). Phosphorus removal in MBBR reactors is up till now done with use of precipitation chemicals.

The Norwegian utility Hias IKS has developed the Hias Process, which is a continuously operated single MBBR reactor (Saltnes et al, 2017). The Hias Process removes organic matter, phosphorus via EBPR, and both nitrogen and phosphorus via simultaneous nitrification and denitrification P-removal (SND-P). The Hias Process has been operated in demonstration scale (10 000 pe) since 2016 with excellent results for phosphorus removal (PO4-P < 0,20 mg/l) and with steady 50% N-removal. Due to the compactness of MBBR technology, the solution is very volume-to-area efficient compared to current state of the art for BNR. Minimal use of precipitation chemicals and external carbon sources results in favourable OPEX.

The presentation will cover the design and function of the Hias Process, present long-term results in demonstration scale, and present the ongoing retrofit project of a 140 000 PE plant in Norway. A complete process train for full biological removal of phosphorus and nitrogen will be proposed, including phosphorus recovery.



Ødegaard H., Rusten B. and Westrum T. (1994). A new moving bed biofilm reactor – application and results. Water Science and Technology, 29 (10-11), 157-165

Saltnes T., Sørensen G. and Eikås S. (2017). Biological nutrient removal in a continuous biofilm process. Water Practice and Technology, 12 (4), 797-805

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