School of Environmental Science and Engineering, Tianjin University, No. 35 Yaguan Road, Jinnan District, Tianjin 300350, China.
MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China.
Water Res. 2021 Feb 1;189:116663. doi: 10.1016/j.watres.2020.116663. Epub 2020 Nov 23.
Biomineralized vivianite induced by dissimilatory iron reduction bacteria (DIRB) has received increasing attention because it alleviates phosphorus crisis and phosphorus pollution simultaneously. However, the relatively small crystal size and low Fe(III) reduction rate restrict the separation and recovery of vivianite. In this study, graphite was selected as additive to enhance vivianite biomineralization with soluble ferric citrate and insoluble hematite as two representative electron acceptors. As soluble ferric citrate provided abundant accessible electron acceptors, relatively inconspicuous increase (lower than 7%) was observed for graphite on vivianite formation while inoculated with raw sewage or DIRB. In contrast, graphite considerably increased vivianite formation efficiency by 23% in insoluble hematite inoculated with raw sewage. The graphite promotion on vivianite formation in hematite batch was magnified to 70% by DIRB. Dosing hematite inhibited the supply of electron acceptors, while conductive graphite promoted the electrical connection between minerals and DIRB, thus improved the Fe(III) reduction rate and efficiency. In addition, secondary minerals in hematite exhibited a larger aspect ratio and tended to aggregate on graphite. Graphite enlarged the vivianite size in hematite from 10 µm to 90 µm due to aggregation. Enhancing dissimilatory iron reduction (DIR) rate of iron oxides and enlarging crystal size provide new insights for vivianite formation and separation during wastewater treatment.
异化铁还原菌（DIRB）诱导的生物矿化磷铁矿受到越来越多的关注，因为它可以同时缓解磷危机和磷污染。然而，相对较小的晶体尺寸和较低的 Fe(III)还原率限制了磷铁矿的分离和回收。在这项研究中，选择石墨作为添加剂，以增强生物矿化磷铁矿，以可溶性柠檬酸铁和不溶性赤铁矿作为两种代表性的电子受体。由于可溶性柠檬酸铁提供了丰富的可及电子受体，因此在接种原污水或 DIRB 时，石墨对磷铁矿形成的影响相对较小（低于 7%）。相比之下，在接种原污水的不溶性赤铁矿中，石墨使磷铁矿的形成效率提高了 23%。在 DIRB 接种的赤铁矿批处理中，石墨对磷铁矿形成的促进作用放大到 70%。赤铁矿的添加抑制了电子受体的供应，而导电石墨促进了矿物与 DIRB 之间的电连接，从而提高了 Fe(III)还原率和效率。此外，赤铁矿中的次生矿物表现出更大的纵横比，并倾向于在石墨上聚集。由于聚集，石墨使赤铁矿中的磷铁矿尺寸从 10 µm 增大到 90 µm。提高氧化铁的异化铁还原（DIR）速率和增大晶体尺寸为废水处理过程中磷铁矿的形成和分离提供了新的思路。
