Huang Haiming, Huang Lingyun, Zhang Qingrui, Jiang Yang, Ding Li
Hebei Key Laboratory of Applied Chemistry, School of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, PR China.
Hebei Key Laboratory of Applied Chemistry, School of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, PR China.
Chemosphere. 2015 Oct;136:289-96. doi: 10.1016/j.chemosphere.2014.10.078. Epub 2014 Nov 20.
Struvite (MgNH4PO4⋅6H2O) precipitation is a promising method for ammonium (NH4(+)) removal from the wastewater. However, the high cost incurred with the use of magnesium and phosphate sources hinders the successful application of this method. This paper presents a novel recycling technology of struvite that is based on the chlorination decomposition of struvite. The study results indicated that struvite can be effectively decomposed by sodium hypochlorite and that the solid/liquid ratio of struvite in solution did not affect the ammonium-nitrogen (NH4-N) decomposition efficiency of struvite. Through the analysis of the reaction process, the mechanism of struvite decomposition was proposed to be simultaneous dissolution and oxidation of struvite, and the main component of the decomposition product generated was determined to be newberyite, dissolved HPO4(2-) and Mg(2+), and magnesium phosphate. When the decomposition product was recycled, its pH had to be adjusted for high NH4-N removal. NH4-N of 92% could be removed from landfill leachate when the decomposition product solution pH before recycling was adjusted to 3 and the precipitation pH was maintained at 9. A five-cycle recycling process showed that recycling of struvite chlorination decomposition product was a highly efficient and sustainable method for the removal of NH4-N. An economic evaluation showed that the use of recycled struvite for the five-process cycles by the proposed process could save the cost of chemicals by approximately 34% as compared to the use of pure chemicals.
鸟粪石（MgNH4PO4⋅6H2O）沉淀是一种从废水中去除铵（NH4(+)）的有前景的方法。然而，使用镁源和磷源所产生的高成本阻碍了该方法的成功应用。本文提出了一种基于鸟粪石氯化分解的新型鸟粪石回收技术。研究结果表明，次氯酸钠可有效分解鸟粪石，且溶液中鸟粪石的固液比对鸟粪石的铵氮（NH4-N）分解效率没有影响。通过对反应过程的分析，提出鸟粪石分解的机理是鸟粪石的同时溶解和氧化，并确定分解产物的主要成分是磷酸新镁石、溶解的HPO4(2-)和Mg(2+)以及磷酸镁。当回收分解产物时，必须对其pH进行调节以实现高NH4-N去除率。当回收前分解产物溶液的pH调节至3且沉淀pH维持在9时，可从垃圾渗滤液中去除92%的NH4-N。一个五循环的回收过程表明，鸟粪石氯化分解产物的回收是一种高效且可持续的去除NH4-N的方法。经济评估表明，与使用纯化学品相比，采用所提出的工艺将回收的鸟粪石用于五个工艺循环可节省约34%的化学品成本。
