Performance of Fe-dosing membrane bioreactor and evaluation of phosphorus recovery as vivianite after long-term operation

In this study, the influence of high concentration of iron on the nutrient removal, membrane fouling and microbial diversity of membrane bioreactor for wastewater treatment were systematically investigated. Moreover, the potential of phosphorus recovery in the form of vivianite was assessed after the long-term operation. The results show that TP concentration in effluent was decreased to 1.07 +/- 0.47 mg/L (without Fe addition), 0.41 +/- 0.23 mg/L (Fe/P = 2), 0.20 +/- 0.12 mg/L (Fe/P = 4). Compared with control group, the TN concentration in effluent was higher at the high concentration of iron, which was due to the decreased nitrite-oxidizing bacteria (NOB) by microbial population analysis. Membrane fouling was alleviated by enlarging floc size and reducing supernatant COD via adding iron. Besides, it was detected that the amorphous ferric oxide and Fe(III) bound phosphorus were the main Fe and P speciation and vivanite (ca. 29 %). The anaerobic environment was conducive to the formation of vivianite and the phosphorus recovery as vivanite was recommended based on the results of current study.