Use of a byproduct of magnesium oxide production to precipitate phosphorus and nitrogen as struvite from wastewater treatment liquors.
This paper describes a series of experiments designed to recover phosphorus and nitrogen from sewage in the form of struvite (MgNH(4)PO(4).6H(2)O), a potential fertilizer. Nitrogen and phosphate were recovered from a filtrate of digested sludge dewatered at the Arroyo del Soto Waste Water Treatment Plant (WWTP) (Madrid, Spain). A byproduct of the Spanish magnesite mining and MgO production industry was used as the magnesium source. The precipitating performance of this byproduct was compared to that of conventional chemical reagents such as pure MgO. The precipitates obtained were subjected to chemical, light microscopy, and X-ray diffraction analysis. The findings indicate the precipitate recovered using this byproduct contains several minerals with a predominance of struvite. Optimal purity ( approximately 80% struvite) was achieved using the sieved <0.04 mm grain size fraction of the byproduct at doses corresponding to a molar Mg:P ratio of 1.6.
Quintana
Miguel
M
Consejo Superior de Investigaciones Científicas, Centro de Ciencias Medioambientales, C/Serrano, 115-duplicado, 28006 Madrid, Spain.
Colmenarejo
Manuel Fco
MF
Barrera
Jesús
J
García
Gema
G
García
Elia
E
Bustos
Angel
A
D011232:Chemical Precipitation; D006863:Hydrogen-Ion Concentration; D017616:Magnesium Compounds / Q000737:chemistry*; D008277:Magnesium Oxide / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry* / Q000302:isolation & purification; D010710:Phosphates / Q000737:chemistry*; D010758:Phosphorus / Q000737:chemistry* / Q000302:isolation & purification; D012722:Sewage / Q000737:chemistry*; D000069877:Struvite
D017616:Magnesium Compounds; D010710:Phosphates; D012722:Sewage; D010758:Phosphorus; D008277:Magnesium Oxide; D000069877:Struvite; D009584:Nitrogen