Chitosan-Modified Bentonite Clay as Low-Cost Coagulant Aid for Removal of Colloidal Particles from Turbid Water

Abstract

The presence of colloidal particles in turbid water significantly affects water quality and poses challenges for conventional treatment processes due to the stability of suspended contaminants. This study investigates the application of chitosan-modified bentonite clay as a low-cost coagulant aid for the removal of colloidal particles from turbid water under controlled treatment conditions. The research focuses on evaluating coagulation performance, particle destabilization mechanisms, and operational factors influencing turbidity reduction efficiency. Experimental analyses were conducted to examine the effects of pH, coagulant dosage, mixing intensity, settling time, initial turbidity, and chitosan loading on floc formation and particle removal performance. Results demonstrated that chitosan modification significantly enhanced the adsorption and coagulation properties of bentonite clay through improved charge neutralization and polymer bridging mechanisms. The modified material exhibited high turbidity removal efficiency and rapid floc settling characteristics compared with unmodified bentonite and conventional treatment aids. Optimized operating conditions substantially improved colloidal particle aggregation and reduced residual turbidity in treated water. Kinetic and surface interaction analyses revealed that electrostatic attraction and adsorption phenomena strongly influence coagulation efficiency and floc stability. The study further indicated that the use of naturally derived chitosan and clay-based materials offers environmental and economic advantages through reduced chemical consumption and biodegradable treatment components. Comparative evaluation with traditional synthetic coagulant aids confirmed the effectiveness of chitosan-modified bentonite as a sustainable alternative for water clarification applications. The findings highlight the potential of this composite material for low-cost and efficient treatment of turbid water in municipal, rural, and decentralized water purification systems.