Views:8 Author:Site Editor Publish Time: 2017-04-27 Origin:Site
From the earliest use of natural coagulants to primary synthesis of AlC13, FeS04-7H20 or silicone series coagulants, and then to the use of high polymer coagulants (such as PAC, PFS, PASS, PAM, etc.), as well as the upcoming biological coagulant. The process of using coagulants in humans also undergoes a cycle from natural to synthetic to natural.
The advantages of inorganic coagulants are economical, simple in usage, but large consumption, high cost, strong corrosion and low in flocculation. Inorganic polymer coagulant is a new type of wastewater treatment agent developed in the late 1960s. Compared with the traditional coagulant, it can improve the efficiency, and the price is low, so it has gradually become the mainstream trend.
Compared with inorganic coagulant, organic polymer coagulant has the advantages of less dosage, wide application range, less influence of salt and environmental conditions, less sludge and good treatment effect, has aroused people's wide attention.
Natural polymer coagulant (biological coagulant) is rich in raw materials, low price, high selectivity, small dosage, safe and non-toxic, can be completely biodegradable, no secondary pollution, not affected by the change of pH value. Therefore, it has attracted more and more attention in many coagulants. After decades of development, there have been a large number of different properties and uses of coagulants, such as starch, lignin, chitosan, plant gum, proteins, algae and so on. In the natural polymer coagulant, the starch source is wide and the price is low, and its graft copolymerization is a branched structure, which can disperse the flocculating group, It has a strong ability to capture and accumulate the particles in the suspension system, and its graft copolymerization is especially noticeable.
In the preparation of coagulant, considering the different characteristics of various coagulants, so as to synthesize a variety of composite coagulants, modified to produce amphoteric coagulant, including modified natural polymeric coagulants made from various natural polymeric coagulants, such as amphoteric starch coagulants; and amphoteric polymeric macromolecule coagulants, such as amphoteric polyacrylamide.