Under a modified phosphogypsum (MPG) treatment, the effective removal of bound water and risky heavy metals from sludge has been achieved. In this paper, the effects of the operating parameters on sludge treatment, variations of the active groups in the sludge, and the heavy metals' mobility risk were investigated. The results showed that adding 40–50% DS (mass of dry solid in sludge) of MPG could directly remove approximately 62% of bound water from the sludge. Moreover, about 23.96% of Cd_F1/F2, 39.92% of Cr_F1/F2, 21.21% of Zn_F1/F2, 35.49% of Ni_F1/F2, and 78.61% of As_F1/F2 were removed from the sludge due to a transition of risky heavy metals (metal-F1/F2) to stable heavy metals (metal-F3/F4/F5). Simultaneously, organic chelation was more effective in stabilizing Cd, Cr, Zn, and As. Additionally, the flocs entrainment can significantly improve the stabilization of Ni and Pb. In addition, the risky model of heavy metals showed that a higher oxidization performance of the sludge and less loosely bound extracellular polymeric substances (LB-EPS) content was propitious to the immobilization of Cd, Cr, Zn, Ni, and As. Nevertheless, the environmental risk of Cu and Pb varied with the addition of MPG. These results indicate the potential of this method for the synergetic removal of bound water and risky heavy metals from sludge.

中文翻译：

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絮凝剂改性磷石膏对污泥处理的影响：研究污泥中的操作参数，化学基团和重金属的变化

在改良的磷石膏（MPG）处理下，已经实现了从污泥中有效去除结合水和危险重金属的方法。本文研究了操作参数对污泥处理，污泥中活性基团变化以及重金属迁移风险的影响。结果表明，添加MPG 40–50％（污泥中的干固体质量）可以直接从污泥中去除约62％的结合水。此外，Cd _{F1 / F2}为约23.96％，Cr _{F1 / F2}为39.92％，Zn _{F1 / F2}为21.21 ％，Ni _{F1 / F2}为35.49 ％，As _{F1 / F2}为78.61％由于危险的重金属（金属F1 / F2）向稳定的重金属（金属F3 / F4 / F5）过渡而从污泥中去除。同时，有机螯合在稳定Cd，Cr，Zn和As方面更有效。另外，絮凝物夹带可以显着改善Ni和Pb的稳定性。此外，重金属的危险模型表明，污泥的较高氧化性能和较少的松散结合的细胞外聚合物（LB-EPS）含量有利于Cd，Cr，Zn，Ni和As的固定化。然而，铜和铅的环境风险随MPG的添加而变化。这些结果表明该方法可协同去除污泥中的结合水和危险重金属。