There are many types of sewage treatment agents, with the most commonly used being flocculants, which can be divided into inorganic and organic types.

Inorganic flocculants can be classified into low molecular weight and high molecular weight based on their molecular weight.

1、 Low molecular weight inorganic flocculants

Inorganic flocculants are widely used in iron based and aluminum based metal salts. The mainstream inorganic coagulants in the market include ferric chloride, ferrous sulfate, and aluminum sulfate.

The water molecular formula of ferric chloride is (FeCl3 · 6H2O)

Features: The formed alum flowers have good precipitation properties, and are more effective in treating low-temperature or low turbidity water than aluminum salts. The suitable pH range is wider, but the color of the treated water is higher than that of aluminum series, and it is corrosive.

The molecular formula of ferrous sulfate is (FeS04 · H20)

Characteristic: The dissociated Fe2+can only generate simple mononuclear complexes, and does not have the same good coagulation effect as trivalent iron salts.

The molecular formula of aluminum sulfate is Al2 (S04) 3

Features: Aluminum sulfate is a commonly used flocculant in wastewater treatment, which is convenient to use and has good flocculation effect;

Disadvantages: Hydrolysis is difficult when the water temperature is low, resulting in loose flocs; Its effective pH range is relatively narrow.

Mingji (Al2 (S04) 3 · K2S04.24H20) is similar to aluminum sulfate.

2、 Polymer inorganic flocculant

Inorganic polymer flocculants have high coagulation efficiency and low cost, making them a commonly used flocculant. It can be divided into cationic and anionic types according to different ionic degrees

Cationic type: there are polyaluminum chloride, polyaluminum sulfate, polyaluminum phosphate, polyaluminum sulfate, polyaluminum iron chloride, etc.

There are fewer types of anionic inorganic flocculants, and the more mainstream one is polysilicic acid.