Discuss the difference between aluminum salt and iron salt can be compared by what? Discuss the difference between aluminum salt and iron salt can be compared by what? In wastewater treatment, iron salts are usually represented by ferrous sulfate or polyferric sulfate. Aluminum salts are often represented by polyaluminum chloride or aluminum sulfate, all of which have the effect of coagulation. So, the difference between aluminum and iron salts and which one is better? In most cases, iron salts and aluminum salts can be used instead of each other, they are good for the treatment of decolorization of water, COD, phosphorus, sulfur, heavy metals and so on. They and calcium salts collectively referred to as the three major salt. The same polymer polymer of aluminum chloride and polyferric sulfate, respectively, on behalf of high polymer aluminum salt and polymer ferric salt coagulation effect salt as an example, the problem is discussed. Polymeric ferric sulfate itself is an acidic agent, the pH value of 2 to 3, while the pH of the polymeric aluminum is 3.5 to 5, we can see that, in addition to polymeric ferric sulfate can be used in weak acid conditions, its own low pH value , Also applies to alkaline conditions, relative to the poly aluminum is more suitable for high pH wastewater. From the decolorization, as the case may be, but in general, the use of iron salts may be excess iron ions, yellow water quality of the phenomenon. Ferrous ions, however, are reducible and can be subjected to reductive decoloration. The formation of iron hydroxide or polynuclear complexes are water color groups have great adsorption decolorization effect, and this kind of flocculation decolorization of aluminum salt, and if excessive aluminum salt, the water will not Color. Therefore, from the decolorization can be based on the actual needs of dyes and other selected products. From the flotation process, aluminum salt is more applicable than iron salts. This is due to its relatively heavy molecular weight, the formation of alum particles are not easily broken. From the settlement of the process, the two flocculation treatment, the formation of aluminum salts floc larger, but its sedimentation than iron salts, therefore, in the settlement process, the use of iron as a flocculant. From the water quality, the iron salt mostly acidic, used in alkaline wastewater more. The aluminum is more used in neutral, weak acid, weak alkaline wastewater treatment.