A new and efficient approach for phosphorus recovery from wastewater in the form of vivianite mediated by iron-reducing bacteria

The phosphorus adsorbing ability of iron minerals is limited. The bio-reduction of Fe(III) provides a prospective process for improving the recovery of phosphorus. With the addition of Shewanella oneidensis MR-1 to an ‘iron mineral–phosphorus’ system, the recovery of phosphorus for ferrihydrite and magnetite systems increased from 90.12% to 99.43% and from 18.18% to 97.96%, respectively. This was mainly due to the biogenic Fe(II) present after the iron reduction process, which combined with phosphorus to form vivianite. After 75 h of iron reduction, phosphorus was added. For the relative low dose of phosphorus (30 mg·L−1), the proportions of phosphorus recovery in the form of vivianite in ferrihydrite and magnetite systems were 18.95% and 14.55%, respectively. When the phosphorus concentration increased to 150 mg·L−1, the proportions of vivianite in ferrihydrite and magnetite systems increased to 53.18% and 35.42%, respectively. For batch-dosing phosphorus system (150 mg·L−1 phosphorus), it could be treated 4 batches in the ferrihydrite system within 572 h and 3 batches within 806 h in the magnetite system. On the premise that 95% phosphorus was recovered, the yield of vivianite also increased. The X-ray diffraction patterns showed that the transformation of iron minerals could be controlled by the concentration of the soluble Fe(II). Therefore, the recovery of phosphorus increased due to the combination of the iron reduction process and changing the phosphorus dosing time, which provided basic data for the recovery of phosphorus in wastewater.