ABSTRACT

Phosphogypsum (CaSO₄) is produced as a waste by-product during phosphoric acid production in the fertilizer industry. Only 15% of worldwide phosphogypsum production is recycled, while 85% is stored in the vicinity of factories as huge piles resulting in environmental and health hazards. An extensively studied biotransformation of phosphogypsum to calcium carbonate or calcite (CaCO₃) using sulfate reducing bacteria (SRBs) is a prolonged process and results in the formation of extremely hazardous H₂S gas. Here we report for the first time a novel approach for biotransformation of phosphogypsum to CaCO₃ using urease producing Lysinibacillus sphaericus strain GUMP2. The strain could effectively transform phosphogypsum to crystalline, bead-shaped CaCO₃ precipitates. In a batch reactor with the PG loading rate of 60 g/L, 100% biotransformation was observed within seven days. After calcite recovery, the ammonium sulfate formed in the supernatant was recovered by precipitation. Urease-producing L. sphaericus strain GUMP2 could be used to remove the hazardous phosphogypsum from the environment by converting it to the industrially useful CaCO₃ and ammonium sulfate, a valuable agricultural fertilizer. This novel and sustainable approach could be a promising solution for the hazardous phosphogypsum in the phosphoric acid industries.

摘要

磷石膏 (CaSO ₄ ) 是化肥工业中磷酸生产过程中产生的废副产品。全球只有 15% 的磷石膏产量被回收利用，而 85% 的磷石膏作为大堆堆放在工厂附近，对环境和健康造成危害。广泛研究的使用硫酸盐还原菌 (SRB) 将磷石膏生物转化为碳酸钙或方解石 (CaCO ₃ ) 是一个漫长的过程，会导致形成极其危险的 H ₂ S 气体。在这里，我们首次报道了一种使用产脲酶球形赖氨酸杆菌将磷石膏生物转化为 CaCO _{3的新方法}菌株 GUMP2。该菌株可以有效地将磷石膏转化为结晶的珠状CaCO ₃沉淀物。在 PG 负载率为 60 g/L 的间歇式反应器中，7 天内观察到 100% 的生物转化。回收方解石后，通过沉淀回收上清液中形成的硫酸铵。产脲酶球形乳杆菌菌株 GUMP2 可用于通过将磷石膏转化为工业上有用的 CaCO ₃和硫酸铵（一种有价值的农业肥料）来从环境中去除有害磷石膏。这种新颖且可持续的方法可能是磷酸工业中有害磷石膏的有前途的解决方案。