Surface charge studies - an important approach for investigation of color removal from textile wastewaters by chemical coagulation

Results concerning surface charge characterizations of coagulated dye with an aim to evaluate the predominant destabilization mechanism taking place during colour removal by chemical coagulation are presented. A model wastewater comprising of commercially used dye with a CI “Reactive Red 2” was studied. The effect of the combination coagulant/flocculant on colour removal by filtration and sedimentation was evaluated in terms of progression of sludge surface charge. On that basis, an implications about the predominant colour removal mechanisms have been drawn. On selected sludge samples, floc characterisations in terms of size by laser scattering and shape were performed. The measurement techniques used have encompassed for particle size and Small Angle Light Scattering (SALS) for fractal dimension.