One-step processing of waste dredged slurry into planting soil by targeted pretreatment and vacuum filtration

Abstract

A novel method, targeted pretreatment and vacuum filtration (TP-VF), is introduced and validated in this study. TP-VF offers a one-step solution for efficiently dewatering dredged slurry (DS) characterized by heavy metal contamination, high salinity, and excessive moisture content. This innovative approach combines targeted pretreatment (TP) and vacuum filtration (VF) to transform DS into the viable planting soil. TP encompasses a dual optimization strategy that enhances both slurry dewatering efficiency and the quality of the resultant planting soil (cake). By employing flocculation pretreatment, TP increases the size of flocs and enlarges cake pores, leading to improvements in dewatering efficiency and infiltration rates. Additionally, targeted pretreatment results in the discharge of approximately 90% of heavy metal ions and most salts with the filtrate. Remarkably, the addition of chelating agents and freshwater as part of the pretreatment process positively impacts soil quality without compromising floc size or dewatering efficiency. Comparatively, TP-VF demonstrates a substantial reduction of 35.81% in operational costs when contrasted with the traditional two-step process, concurrently diminishing the potential for secondary environmental pollution. This study highlights TP-VF as a promising advancement in sustainable slurry management, addressing pressing environmental challenges while optimizing resource utilization.

Keywords: Dredged slurry; Filtration; Planting soil; Targeted pretreatment.