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Updated: Aug 16, 2025

Electrochemically and Bioelectrochemically Induced Ammonium Recovery
Published on: January 22, 2015
Scalant Removal at Acidic pH for Maximum Ammonium Recovery
Hanna Kyllönen1, Juha Heikkinen1, Eliisa Järvelä1
1VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044 VTT Espoo, Finland.
Concentrating ammonium nitrogen (NH4-N) from industrial wastewater requires scalant removal. Acidic precipitation followed by NF90 membrane filtration effectively concentrated NH4-N from 0.17 g/L to 3 g/L.
Area of Science:
- Environmental Engineering
- Water Treatment Technologies
- Resource Recovery
Background:
- Industrial side streams contain valuable ammonium nitrogen (NH4-N) but at low concentrations.
- High concentrations of ammonium nitrogen (NH4-N) are needed for effective recovery.
- Scalant removal is a critical step for concentrating ammonium nitrogen (NH4-N).
Purpose of the Study:
- To investigate scalant removal methods for concentrating ammonium nitrogen (NH4-N).
- To evaluate the effectiveness of different pH precipitation methods and membrane filtration for NH4-N recovery.
- To assess the performance of nanofiltration (NF) membranes for concentrating NH4-N.
Main Methods:
- Precipitation of scalants using sodium carbonate (Na2CO3) at alkaline pH.
- Precipitation of scalants using oxalic acid (C2H2O4) at acidic pH.
- Concentration of ammonium nitrogen (NH4-N) using nanofiltration (NF) membranes (NF90 and NF270) and reverse osmosis (RO).
Main Results:
- Alkaline precipitation required high Na2CO3 doses to remove calcium and sulfate scalants.
- Ammonium nitrogen (NH4-N) remained in solution during alkaline pre-treatment but was poorly rejected by RO.
- Acidic pre-treatment with oxalic acid followed by NF90 achieved NH4-N concentration from 0.17 g/L to 3 g/L.
- NF90 demonstrated successful large-scale application for NH4-N concentration.
Conclusions:
- Acidic pH pre-treatment with oxalic acid is effective for scalant removal and subsequent ammonium nitrogen (NH4-N) concentration.
- The NF90 membrane is suitable for concentrating ammonium nitrogen (NH4-N) from pre-treated industrial wastewater.
- This study demonstrates a viable method for recovering ammonium nitrogen (NH4-N) from industrial effluents.
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