Polysaccharide based Graft Copolymers and their Applications as Flocculants for Drilling Fluid Wastes

Abstract

Pure water is essential for the survival of living beings. It is used for human consumption, agricultural and industrial activities. During oil and gas well drillinglarge amount of drilling fluid are used. These drilling fluids are mainly water based bentonite solutions which plays a major role in keeping safe and efficient oil and gas well drilling. After their prolonged use, these drilling fluid wastes needs to be disposed of in an environmentally and economically acceptable manner. The removal of the contaminants from the effluents involves the process of coagulation and flocculation. The above processes help in waste minimization, recycling, solid control and the final disposal of the separated solids and liquids. Inorganic coagulants and organic flocculants are widely used for coagulation and flocculation processes. Addition of salts and variation of the pH of the system can optimize the coagulation and flocculation processes. Polyacrylamide based synthetic polymers as flocculants are found to be shear degradable and polysaccharide based natural polymers are found to be biodegradable. Recently, grafted polysaccharides on rigid polysaccharide backbones are found to be better flocculating agents with both shear degradable and biodegradable resistance. This paper accounts for the present status of the synthesis, characterization, and applications of graft copolymers for flocculation of drilling fluid waste.