There are many sewage treatment reagents. The common reagent is the flocculant. The flocculant can be divided to the inorganic and organic flocculant.
Based on the molecular weight, the inorganic flocculant can be divided to the inorganic flocculant with low and high molecular weight.
Inorganic Flocculant with Low Molecular Weight
The Fe and Al base metallic salts are widely applied. The main products in the market are cpolyaluminium chLoricle, ferric trichloride, ferrous sulfate and aluminum sulfate. Cpolyaluminium chLoricle is a kind of new-typed mainstream inorganic polymeric flocculant. Because it is more efficient in the water process than the traditional inorganic reagents, it is rapidly developed and widely applied.
Molecular Formula of Ferric Trichloride is FeCl3·6H20
Character: Good sedimentation of alumen ustum, better results in processing the low-temperature water or low-turbidity water than aluminum salt, wide application scope of PH, higher chromaticity of water after treatment than the aluminum base, with corrosivity.
Molecular Formula of ferrous sulfate is FeS04·H20
Character: Fe2+ dissolved can be generated to the simple mononuclear complex, worse coagulation results than ferrous salts.
Molecular Formula of aluminum sulfate is Al2(S04)3
Character: It is the flocculant widely used during the processing of wastewater. Easy use and good coagulation results. When the water temperature is low the water dissolution is difficult. The alum floc generated is much looser. Its effective scope of PH value is narrow. The functional mechanism of (Al2(S04)3·K2S04.24H20 is similar with the aluminum sulfate.
Macromolecule Inorganic Flocculant
With good coagulation results and low price, the inorganic flocculant becomes the mainsteam inorganic flocculation reagent. The inorganic polymer flocculant can be divided into the cation-type and anionic-type. Cation-type: including aluminium polychlorid, polyaluminium sulfate, polyaluminium phosphate, polymerization ferric sulfate, polymerization ferric chloride, polymerization iron phosphate, ferrous polymerization. There is few variety of anionic-type inorganic flocculant. The mainstream anionic-type inorganic flocculant is polymerization silicate acid in 2013.
The organic flocculant includes the ionic type and non-ionic type.
The ionic organic flocculant can not only change the charges of particle surface, but also can act as the bridge chain and generate the coagulation. For example, the polyacrylamide (also called flocculant 3) is used to speed up the rapid sedimentation of concentrate ore in the thickening tank so as to lower the water contents of concentrate ore and decrease the metal loss.
The organic flocculant normally has big molecular weight. They can reach tens of thousands, hundreds of thousands, even millions. So, less addition can play a part of bridge chain.
