Turbidity and Color Reduction of Reused Boron-Based Solution from Wood Preservation Process of Rubber wood Processing Industry by Coagulation and Flocculation

Abstract

The reusability of boron solution in wood preservation process using pressure impregnation process of the rubber wood processing industry causes the color in the solution to change from colorless to dark brown and even black as the increase number of its reused cycles. Applying those solutions to the process affects the natural color of the treated wood. This research was conducted to investigate the efficiency of coagulation and flocculation to reduce the turbidity and color of boron solution that was used as wood preservative. Types of coagulants, coagulant dosage and initial pH of boron solution were studied. Results showed that the maximum reduction of turbidity and color occurred when alum, ferric chloride (FeCl3), and polyaluminium chloride (PAC) at the amount of 4.7, 1.7, and 3.3 g/L, respectively, was added to boron solution with initial pH of 8.0. At the stated conditions, removal efficiency for turbidity were as follows: PAC (95.6%) > FeCl3 (92.1%) > Alum (87.4%). Color removal efficiency were as follows: FeCl3 (97.8%) > PAC (96.7%) > Alum (96.1%). The results of the current study can be used as preliminary information for the selection of coagulants for the removal of turbidity and color of boron solution for recycling purpose in the wood preservation process.