Multi-dimensional evaluation of the dry dosing method in Cd and Pb removal by biomineralization: Life cycle...

Biomineralization is a green and efficient method for removing heavy metals from wastewater. However, scant exploration of implementation details hinders its practical applications. In this study, the productivity of phosphate mineralizing bacterial agents prepared via cyclic fermentation reached 2.658 g/L. Compared to the wet dosing method, bacterial agents showed a slight decrease in Cd and Pb removal efficiency, which remained at 80.61 % and 55.64 %, respectively. However, its total environmental impact significantly decreased by 42.34 % for Cd and 65.12 % for Pb removal. The resulting mineralization products exhibited high stability. Therefore, the dry dosing method was considered the preferred choice for practical applications. Drawing on mass transfer laws and reaction features, a mechanistic model was proposed to describe and explain dry dosing kinetics. The dry dosing method displayed stable performance against organic shock loads but struggled with toxic challenges. Besides, the bacterial agents demonstrated robust cyclic performance, particularly for Cd removal. Hydroxylation of mineralized products progressed over time, leading to enhanced stability. Humification and aromatization of components in the loosely bound extracellular polymeric substances (LB-EPS) provided the oxidation driving force for mineral conversion. This research enriched the theoretical system of biomineralization to guide its practical applications.