Comparison of effects of polyaluminum chloride and aluminum sulphate in the treatment of pulp wastewater Comparison of the effects of polyaluminum chloride and aluminum sulphate in the treatment of pulp waste water Polyaluminum chloride has a significant effect on pulp pH and conductivity when compared to aluminum sulphate small. Because of the small drop of pH value of pulp, the application of polyaluminum chloride in neutral papermaking is created. The amount of aluminum sulfate and polyaluminum chloride increased, the soluble charge of pulp and the positive charge of surface charge increased. When the total aluminum concentration was the same, polyaluminum chloride had stronger ability to increase the electropositivity of pulp suspension. Polyaluminum chloride Is more effective than aluminum sulfate cationic aggregator. The effect of pH value on the surface charge density of aluminum sulfate-added pulp is great. The pH increases and the positive charge of surface charge decreases. The pH value is an important factor that limits the performance of aluminum sulfate. Adding polyaluminum chloride pulp, pH value increases, the pulp electropositive instead increases, the pH value of more than 6, CRT significantly increased. The pH value of rosin sizing effect, aluminum sulfate at pH below 5.5, showing good sizing effect, but the pH value of 5.5, sizing effect is not as good as polyaluminum chloride. Polyaluminum chloride in sour to neutral wide range of sizing, pH greater than 6.5, sizing more reduced. Polyaluminum chloride and aluminum sulfate can improve paper retention and drainage properties, polyaluminium chloride effect is more obvious. With the increase of pH value, the retention effect of polyaluminum chloride and aluminum sulfate decreased, but the retention of aluminum sulfate in neutral range decreased more greatly.