Use of Upflow Fluidized Bed Reactor (FBR) for Recovery Phosphorus from Waste-Water Through Struvite Precipitation

The effect of temperature on struvite formation (magnesium, ammonium, phosphate, MAP) was studied in a laboratory scale continuous FBR. MAP precipitation was carried out using magnesium, ammonium and phosphorous source in the synthetic wastewater which was prepared using MgCl2 H3PO4 and NH4OH, while Mg+2, NH4+ and PO4-3 was set-up in a molar ratio of 1:1:1. The supernatant solution was precipitated by adjusting its pH with 1 N KOH. Material characterization of the precipitate was performed using XRPD Rietveld method for mineralogical phase identification and SEM/EDX for morphology and elemental analysis. It was shown that the rate of reaction is very fast completed almost in minutes. This simplifies the process design yielding in a smaller reaction vessel. The results showed that mass of crystals at rate of 27.51 mg/h was recovered during this experiment. The XRD Rietveld method confirmed that the pure struvite crystals were found in the precipitate. An irregular platy shape morphology was observed under SEM imaging. The elemental analysis of the sample was composed of Mg, P, N and O belonging to struvite. The crystallite size of struvite appears to decrease with increasing temperature. Obviously the reactor can produce struvite at a high rate.