Recovery of nitrogen and phosphorous as struvite from swine waste biogas digester effluent / 生物医学与环境科学（英文）

ABSTRACT

<p><b>OBJECTIVE</b>To investigate the feasibility of nitrogen and phosphorus recovery from swine waste biogas digester effluent and the effects of pH and NH4+ Mg2+ PO4(3-) molar ratio on its precipitation.</p><p><b>METHODS</b>Precipitation experiments with swine waste biogas digester effluent were conducted at pH 7.5, 8.0, 8.5, and 9.0 together with NH4+ Mg2+ PO4(3-) molar ratios 1 0.2 0.08, 1 1 1, and 1 1.5 1.5. Chemical and X-ray diffraction (XRD) analysis were done to determine the composition of the precipitate.</p><p><b>RESULTS</b>The highest removal and recovery of NH4+ and PO4(3-) were achieved at pH 9.0 in each experiment. The elevation of pH to 9.0 alone could decrease the initial PO4(3-) concentration from 42 mg L(-1) to 4.7 mg L(-1) and 89.2% PO4(3-) recovery was achieved. The pH-molar ratio combination 9.0-1 1.5 1.5 effected 76.5% NH4+ and 68.5% PO4(3-) recovery. The molar ratio of 1 1 1 together with pH elevation to 9.0 was determined to be the optimum combination for both NH4+ and PO4(3-) removal as it recovered over 70% and 97% of the initial NH4+ and PO4(3-), respectively.</p><p><b>CONCLUSIONS</b>Nitrogen and phosphorus can be recovered from biogas digester effluent as struvite.</p>