Classification of flocculants
At present, there are many varieties, from low molecular weight to high molecular weight, from single type to compound type. The general trend is to develop in the direction of cheap, practical, non-toxic and efficient. According to its chemical composition, flocculants can be divided into inorganic flocculants and organic flocculants. Among them, inorganic flocculant includes inorganic coagulant and inorganic polymer flocculant; organic flocculant includes synthetic organic polymer flocculant, natural organic polymer flocculant and microbial flocculant. 1、 Inorganic flocculants are mainly divided into two categories: iron preparation series and aluminum preparation series, of course, including its cluster polymer series. Simple inorganic polymer flocculant, this kind of inorganic polymer flocculant is mainly the polymer of aluminum salt and iron salt. In addition to polyaluminum and Polyferric, there are polyaluminum silicate and its modified products, such as polyaluminum silicate (iron) and polyphosphate aluminum (iron). Polyaluminum ferric chloride sulfate (PAFCS), polyaluminum ferric silicate (PFS) and aluminum iron copolymer composite flocculants are commonly used as modified multi cationic inorganic flocculants. 2、 Organic polymer flocculant organic polymer flocculant is a new type of waste polymer flocculant developed in the late 1960s. Compared with the traditional flocculant, it can double the efficiency, and the price is low, so it has the trend of becoming the mainstream agent. In addition to the stable product quality, the production of organic polymeric flocculants has accounted for 30% – 60% of the total flocculant production. Commonly used, non-ionic organic polymer flocculants, anionic organic polymer flocculants, cationic organic polymer flocculants, cationic derivatives, amphoteric polyacrylamide polymer, acrylamide graft copolymer, etc.
3、 The organic-inorganic composite flocculants are dominated by variety and performance diversification. The most representative research is the synthesis and polymerization of ferric sulfate. 4、 The commercial production of bioflocculant in foreign countries began in the 1990s. Because there is no secondary pollution, it is easy to use and has an attractive application prospect. It is widely used in the treatment of livestock wastewater, Expanded Sludge and colored wastewater. The products of microbial flocculant have not been reported in China.