Research On The Use Of Modified Starch In Water Treatment

In order to wipe off the suspended pollutants and heavy metal ions in wastewater, a great number of organic and inorganic flocculants have been synthesized. However most of them are expensive, micro-toxic and the residual sludge is hard to dispose, which is an important source of second pollution. Thus it is urgent to develop such a kind of water treatment agent as the polymer flocculation that is non-toxic, clean and will not lead to second pollution. Natural polymer is a non-toxic one with lower price and can be easily biodegraded. Meanwhile, the polymer flocculation is suited to not only dispose the wasterwater of complicated quality but also be used alone or with other methods so as to decrease the environmental pollution caused by wasterwater. Consequently it is widely used in the wasterwater treatment and many scholars have paid attention to it in recent years.Among most of the natural modification polymer flocculations, the research and development of starch-modified flocculation is more noticeable. In addition to have the merits mentioned above, the modified starch owns a great number of excellent applied features. Its application to the water treatment will effectively keep off the second pollution. The starch molecular has many hydroxyls, through whose esterification, etherification oxidization and cross link the properties of starch can be changed. It is in the industry that those chemical reactions apply to produce modified starch. Starch can also have grafting copolymerization with some synthetic polymer such as acrylnitrile, acryloid and acrylamide. There are synthetic polymers on its molecular, thus the polymer have the properties of natural and synthetic ones. All these result in the rapid development of research on starch-modified flocculation.Cationic natural polymer modified flocculation Hyamine organic cation polymeric flocculation is synthesized by putting cationic additives into the parent fraction-starch-acrylamide graft polymer. Grafting copolymerization of maize starch-aorylamide have not only molecular effect and reaction of polysaccharide compound but also biotic stability and linear stretch. In contrast with homopolymer, Hyamine organic cation polymeric flocculation has the properties of strong flocculating effect and molecular stability as well as can be widely applied with easily chemical reaction.The properties of Hyamine organic cation polymeric flocculation are studies in kaolinite containing suspension. The experimental results show that it has ideal turbidity removal efficiency and its performance is superior to that of hompolyacrylamide. The remaining turbidity in the treated water decreased to 3.2NTU after adding 4 mg/L Hyamine organic cation polymeric flocculation. The flocculation experiment with municipal wastewater and catering trade wasterwater indicated that both turbidity and color removal ratios are larger than 90% as well as COD removal ratio was above 75%～80% when adding 6～8 mg/L Hyamine organic cation polymeric flocculation.