Prevention of heavy metal contamination of lead-zinc tailings through soybean urease-based biomineralization

Heavy metal contamination is one of the most prominent environmental issues worldwide, and heavy metal tailings are one of the main sources of such contamination. Biomineralization based on enzyme-induced carbonate precipitation (EICP), as a promising technique for the remediation of heavy metals, has many advantages such as high efficiency, greenness and environmental friendliness. In this study, soybean urease solution self-extracted from soybean powder was used to treat lead-zinc tailings. Heavy metal tolerance test, contaminated solution remediation test and lead-zinc tailings biomineralization test, as well as ICP, XRD and SEM-EDS analyses, were conducted to study the prevention of heavy metal contamination of lead-zinc tailings through soybean urease-based biomineralization. The test results showed that both Pb²⁺ and Zn²⁺ reduced the activity of soybean urease, and the effect of Pb²⁺ on urease activity was time-dependent, whereas the effect of Zn²⁺ was immediate. Soybean urease could effectively remove more than 99% of Pb²⁺ and Zn²⁺ in solution by forming protein complexes and inducing calcium carbonate precipitation. Meanwhile, the calcium carbonate precipitated by the soybean urease could encapsulate the tailings, reducing the amount of heavy metals leached by 70%.