Preparing method of poly aluminum chloride inorganic coagulant with low basicity for waste water treatment and purification method of waste water using the inorganic coagulant prepared by the same

摘要

More particularly, the present invention relates to a process for stably producing a low-salt polychlorinated aluminum-based coagulant, and more particularly to a process for producing an aluminum chloride of extremely low salt concentration (0 to 3%) obtained by reaction of aluminum hydroxide with an acid, (5 to 25%) of a polychlorinated aluminum-based coagulant by reacting the mixture with magnesium hydroxide and a mixture of calcium hydroxide as a synergist to produce a low-salt polychlorinated aluminum-based coagulant. The low-salt, polychlorinated aluminum-based inorganic coagulant obtained by the production process according to the present invention can be produced by preparing a PAC-based compound having a primary ultra low salt level (basicity of 0 to 3%) in the production of the required low- And a basicity increasing agent (a mixture of magnesium hydroxide and calcium hydroxide) which is not a conventional basic reducing agent as the basicity adjusting agent is added thereto, it is possible to increase the basicity even in a small amount, so that the process can be easily controlled, and the obtained low- The residual divalent metal ion (free ion) increases the binding force between phosphorus and fluorine anions, thereby assisting the coagulation efficiency of the low-salt-PAC type inorganic coagulant, so that the coagulation efficiency can be further increased.