Preparation and application of coconut shell-based skeleton particles coupled with hydroxypropyltrimethyl ammonium chloride chitosan in sludge dewatering

The sludge dewatering is a significant part of municipal wastewater treatment industry, and efficient disposal techniques for the sludge dewatering is still a challenge among worldwide environmental fields. To achieve sludge reduction, the research and exploitation of environment-friendly natural polymer dehydrating agents have caused broad attention. In this study, a coconut shell-based composite was prepared by grafting hydroxypropyltrimethyl ammonium chloride chitosan (HACC) on the surface of coconut shell skeleton particles as a novel type of dewatering agent. The response surface methodology was used to optimize the preparation process of grafted coco-nut shell-based skeleton particles. The consumption per unit area of HACC could reach 0.1732 g/g under the optimal preparation conditions: reaction temperature at 40°C, material particle size at 120–200 mesh, mass ratio of M1:M2 at 0.75 without dilution, and ultrasonic time for 5 min. Compared to the composites without graft, the dewatering rate of sludge was obviously improved by the grafted coconut shell-based composites under the same treatment procedures. Moreover, the grafted coconut shell-based composite also possessed the potential for effectively adsorbing the total organic matters in sludge dewatering filtrate. This work provides a promising dehydrating agent and disposal method for the practical application of municipal sludge dewatering.