The Use of Ca- and Mg-Rich Fly Ash as a Chemical Precipitant in the Simultaneous Removal of Nitrogen and Phosphorus—Recycling and Reuse

Recycling

卷:4

Henrik Romar¹  Pekka Myllymäki¹  Tao Hu¹  Pekka Tynjälä¹  Ulla Lassi¹  Janne Pesonen¹ 

[1] Research Unit of Sustainable Chemistry, University of Oulu, P.O. Box 8000, FI-90014 Oulu, Finland;

关键词: ammonium;    fly ash;    phosphate;    precipitation;    recycling fertilizer;    struvite;   

DOI  :  10.3390/recycling4020014

来源: DOAJ

【 摘 要 】

The European Union’s circular economy strategy aims to increase the recycling and re-use of products and waste materials. According to the strategy, the use of industry waste material should be more effective. A chemical precipitation method to simultaneously remove phosphorus and nitrogen from synthetic (NH₄)₂HPO₄ solution and the liquid phase of anaerobic digestate using fly ash as a precipitant was tested. Fly ash is a waste material formed in the power plant process. It mainly contains calcium oxide (CaO) and magnesium oxide (MgO). Saturated precipitant solution was prepared from fly ash, which was added in small proportions to (NH₄)₂HPO₄ solution during the experiment. Fly ash’s effectiveness as a precipitant was compared with that of commercial CaO and MgO salts, and it can be observed that fly ash removed as much ammonium and phosphate as commercial salts. Fly ash sufficiently removed ammonium nitrogen and phosphate from the liquid phase of anaerobic digestate, which led to the formation of ammonium magnesium hydrogen phosphate hydrate, struvite (NH₄MgPO₄·6H₂O), and calcium hydroxide phosphate, monetite, CaPO₃(OH). In this study, we have shown for the first time that fly ash can be used to manufacture recycled, slow-release fertilizers from anaerobic digestate.

【 授权许可】

Unknown