Application of modified lignocellulosic materials as green flocculants for brewery wastewater treatment

Abstract

Coagulation–flocculation technique is usually used in wastewater treatment by employing conventional inorganic materials such as alum and ferric chloride. Due to environmental challenges associated with the use of inorganic flocculants, biopolymers are gaining ground as alternative water treatment materials. In the present study, native cellulose and hemicelluloses isolated from sugarcane bagasse were used in the removal of turbidity and biological oxygen demand (BOD) from industrial wastewater. Isolated native cellulose was modified to regenerated cellulose. Also, native cellulose, regenerated cellulose and hemicellulose were carboxymethylated using sodium monochloroacetic acid. Functional groups on the isolated, regenerated, and carboxymethylated biopolymers were examined using Fourier transform infrared spectroscopy (FT-IR) and Carbon (C), Hydrogen (H), Nitrogen (N), Sulfur (S) and Oxygen (O) (CHNS/O) analysis. The degree of substitution for regenerated and carboxymethylated cellulosic materials were measured using recommended standard methods. Carboxymethyl cellulose (CMC) with 1.3 degree of substitution reduced turbidity and BOD by 62.2 and 64%, respectively. Carboxymethyl regenerated-cellulose (CMC-II) at 1.1 degree of substitution reduced turbidity and BOD by 55.6 and 60%, respectively. Carboxymethyl hemicellulose (CMH) with 1.4 degree of substitution was capable of reducing turbidity and BOD by 45.7 and 47%, respectively. Carboxymethylcellulose and hemicellulose have rarely been used in the treatment of brewery wastewater. In the present study, these two novel materials showed a good prospect for application in water and wastewater treatment.