Evaluation of the hydration process of an industrial magnesia compound to obtain struvite crystals: a technique for recovering nutrients

• Autor(a) principal: Castro,Samuel Rodrigues
• Data de Publicação: 2015
• Outros Autores: Araújo,Mahira Adna Cota, Lange,Liséte Celina
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: REM. Revista Escola de Minas (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0370-44672015000100077
• topic: Industrial magnesia compound; Hydration process; Magnesia hydration; Nutrient recovery; Struvite crystallization

Struvite crystallization as a technique for recovering nutrients from wastewater streams has proven to be an attractive alternative to conventional treatments. The process becomes economically viable with the cost reductions related to the chemical reagents, especially magnesium ions. Thus, this study assessed the processing of a cheap and high-grade industrial magnesia compound in obtaining magnesium hydroxide slurries through a hydration reaction using different hydrating agents (magnesium acetate and sodium chloride solutions and water). The optimum hydration condition was achieved in acetate solution with a conversion rate to hydroxide about 67%. The efficiency of the obtained slurries as alternative reagents on the struvite crystallization process was evaluated in terms of the nutrient removal, NH4+-N and PO43--P. In experimental conditions of Mg2+:NH4+:PO43-ratio equal to 1.5:1.0:1.25 and pH equal to 8.5, the best results were achieved by using the magnesium hydroxide slurry obtained in acetate solution, which promoted removals of about 62% and 67% of NH4+-N and PO43--P, respectively. Finally, instrumental analysis confirmed the formation of struvite crystals in a purity degree that allows its use as a potential fertilizer.