Effect of structural characteristics of process water on paper properties made from recycled fiber

In this study, effect of processed water was investigated on paper properties made from recycled fiber. Recycled pulp was supplied from Afrang Noor recycled paper factory and it was prepared from edge-cutted sheets of paper machine. Water also collected as two type of fresh water from plant tap water with conductivity of 213.4 µS/cm and process water from under the wire pit with conductivity of 4524 µS/cm. Pulp after disintegrating by laboratory Valley beater drained on screen with 400 mesh and then used for making standard handsheet with 130±5 g/m2 by two type of fresh water and process water. Water characterized with tests of Turbidity, TSS, MLVSS, TDS, Color and COD and the physical, mechanical and optical properties of papers were also carried out according to TAPPI standard. Results showed that by sedimentation for 24 h, significant changes was led in process water properties in which in sediment water TSS 80%, TDS 15%, Turbidity 53%, Color 8% and COD 15% decreased in comparison to initial sample. Also, using of process water for papermaking was led to loss of burst 30%, tensile 50%, tear 13% and bending stiffness 12% as well as loss in brightness to 17%. Hence, treatment of process water before papermaking is suggested as an essential step.