Abstract：
Biomineralization has garnered significant attention in the field of wastewater treatment due to its notable cost reduction compared to conventional methods. The reinjection water from oilfields containing an exceedingly high concentration of calcium and ferric ions will pose a major hazard in production. However, the utilization of biomineralization for precipitating these ions has been scarcely investigated due to limited tolerance among halophiles towards such extreme conditions. In this study, free and immobilized halophiles Virgibacillus dokdonensis were used to precipitate these ions and the effects were compared, at the same time, biomineralization mechanisms and mineral characteristics were further explored. The results show that bacterial concentration and carbonic anhydrase activity were higher when additionally adding ferric ion based on calcium ion; the content of protein, polysaccharides, deoxyribonucleic acid and humic substances in the extracellular polymers also increased compared to control. Calcium ions were biomineralized into calcite and vaterite with multiple morphology. Due to iron doping, the crystallinity and thermal stability of calcium carbonate decreased, the content of OC = O, NC = O and CO-PO3 increased, the stable carbon isotope values became much more negative, and β-sheet in minerals disappeared. Higher calcium concentrations facilitated ferric ion precipitation, while ferric ions hindered calcium precipitation. The immobilized bacteria performed better in ferric ion removal, with a precipitation ratio exceeding 90%. Free bacteria performed better in calcium removal, and the precipitation ratio reached a maximum of 56%. This research maybe provides some reference for the co-removal of calcium and ferric ions from the oilfield wastewater.
摘要：
与常规方法相比，生物矿化在废水处理领域引起了极大的关注，因为它显着降低了成本。来自油田的含高浓度钙和铁离子的回注水将对生产构成重大危害。然而,由于嗜盐菌对这种极端条件的耐受性有限，因此几乎没有研究利用生物矿化来沉淀这些离子。在这项研究中,使用游离和固定化的嗜盐菌来沉淀这些离子，并比较了效果，同时,进一步探讨了生物矿化机制和矿物特征。结果表明，以钙离子为基础，额外添加三价铁离子时，细菌浓度和碳酸酐酶活性较高；蛋白质含量，多糖，与对照相比，胞外聚合物中的脱氧核糖核酸和腐殖质也增加。钙离子被生物矿化为具有多种形态的方解石和球闪石。由于铁的掺杂，碳酸钙的结晶度和热稳定性下降，OC=O的含量，NC=O和CO-PO3增加，稳定的碳同位素值变得更加消极，矿物质中的β-折叠消失了。较高的钙浓度促进三价铁离子沉淀，而三价铁离子阻碍钙沉淀。固定化菌对三价铁离子的去除效果较好,沉淀率超过90%。游离细菌在钙去除方面表现更好，沉淀率达到最大值56%。该研究可为油田废水中钙离子和铁离子的协同去除提供参考。
