Modern metallurgical and smelting activities discharge the lead-containing wastewater, causing serious threats to human health. Bacteria and urease applied to microbial-induced carbonate precipitation (MICP) and enzyme-induced carbonate precipitation (EICP) are denatured under high Pb concentration. The nano-hydroxyapatite (nHAP)-assisted biomineralization technology was applied in this study for Pb immobilization. Results showed that the extracellular polymers and cell membranes failed to secure the urease activity when subjected to 60 mM Pb. The immobilization efficiency dropped to below 50% under MICP, whereas it due to a lack of extracellular polymers and cell membranes dropped to below 30% under EICP. nHAP prevented the attachment of Pb either through competing with bacteria and urease or promoting Ca/Pb ion exchange. Furthermore, CO from ureolysis replaced the hydroxyl (-OH) in hydroxylpyromorphite to encourage the formation of carbonate-bearing hydroxylpyromorphite of higher stability (Pb(PO)CO). Moreover, nHAP application overcame an inability to provide nucleation sites by urease. As a result, the immobilization efficiency, when subjected to 60 mM Pb, elevated to above 80% under MICP-nHAP and to some 70% under EICP-nHAP. The findings highlight the potential of applying the nHAP-assisted biomineralization technology to Pb-containing water bodies remediation.

中文翻译：

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Pb污染水溶液修复劣化现象及纳米羟基磷灰石辅助生物矿化强化机制

现代冶金、冶炼活动排放的含铅废水，对人类健康造成严重威胁。应用于微生物诱导碳酸盐沉淀（MICP）和酶诱导碳酸盐沉淀（EICP）的细菌和脲酶在高Pb浓度下会发生变性。本研究应用纳米羟基磷灰石（nHAP）辅助生物矿化技术来固定 Pb。结果表明，在 60 mM Pb 作用下，细胞外聚合物和细胞膜无法确保脲酶活性。 MICP 下固定化效率降至 50% 以下，而 EICP 下由于缺乏细胞外聚合物和细胞膜，固定化效率降至 30% 以下。 nHAP 通过与细菌和脲酶竞争或促进 Ca/Pb 离子交换来阻止 Pb 的附着。此外，尿解产生的 CO 取代了羟基焦氯铅矿中的羟基 (-OH)，从而促进了具有更高稳定性的含碳酸盐羟基焦氯铅矿 (Pb(PO)CO) 的形成。此外，nHAP 应用克服了脲酶无法提供成核位点的问题。结果，当使用 60 mM Pb 时，固定化效率在 MICP-nHAP 下提高到 80% 以上，在 EICP-nHAP 下提高到约 70%。研究结果凸显了将 nHAP 辅助生物矿化技术应用于含铅水体修复的潜力。