Large quantities of sludge with a high moisture content are generated by dredging operations, necessitating the implementation of effective techniques for separating the sludge from the water. The objective of dredging is to remove internal pollution
however, it remains uncertain whether natural water bodies are capable of directly receiving the discharge of residual water. Geotextile tube technology has been successfully applied to dredging dewatering. Nevertheless, the technology has not yet been demonstrated to meet the standard for the residual water discharge in the dewatering of polluted sediment. A flocculation conditioning scheme combined with geotextile bag dewatering is proposed in this study as a means of improving the efficiency of mud-water separation and the quality of the residual water after separation. The results indicate that the particle size distribution and moisture content of the original sediment have a significant effect on the sediment-water separation capability of the geotextile tubes. Additionally, the research showed that mixing chitosan and NPAM at a certain ratio can improve the sediment settling performance and the quality of the dewatered the residual water. The leaching tests carried out on the dried sediment treated with coagulant showed that it met the long-term leaching toxicity standards for heavy metals.