Struvite, (MgNH4PO4�6H2O), a common precipitate formed during sewage treatment, has been widely studied as a phosphorus-bearing fertilizer. Contaminants in sewage water will interact with struvite during mineral formation. This study focuses on the interaction between arsenic (As) and struvite as impacted by pH and As oxidation state. An increase in pH from 8 to 11 resulted in the production of more struvite, but with higher As concentration. Pentavalent arsenic (As(V)) was the preferred oxidation state in struvite rather than trivalent arsenic (As(III)), and As(III) was partially oxidized to As(V) at higher pH. The x-ray diffraction (XRD) spectra indicated reduced struvite crystallinity with increased pH. The results from x-ray absorption fine structure (XAFS) spectroscopy revealed that the removal mechanisms of As(V) and As(III) were coprecipitation and adsorption, respectively. This study can help to recover an eco-friendly struvite-based fertilizer with low contaminant content, with implications for addressing the potential world food crisis.

Impact of pH on the coprecipitation of arsenic with struvite

244th National Meeting (2012)

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