Study on Treatment of Printing and Dyeing Wastewater by Multi-type Polymer Flocculant

With the further development of modern industry, the quality of discharged industrial wastewater becomes more and more complex. At the same time, with the increasing awareness of environmental protection in the world, there is a concern that the remaining metal ions (Fe3+, Al3H, etc.) after the use of a traditional single flocculant Water quality has an adverse effect. Therefore, a single flocculant is limited to use in low-level wastewater and sewage treatment, and special flocculants are required for high-demand water such as drinking water.

In the 1980s, the research and development of multi-element polymer flocculants began in China. Due to the late start, the research foundation was weak. So far, there have been few reports on the industrial scale production of such flocculants.

Currently used multi-type polymer flocculants can be roughly divided into three categories: inorganic-inorganic polymer complex flocculants; inorganic-organic polymer complex flocculants; organic-organic polymer complex flocculants.

1 Inorganic-inorganic polymer composite flocculants There are many research reports on multi-element inorganic polymer flocculants u, 2], and its production method is in polyaluminum chloride + PAC), polyaluminum sulfate (PAS), polymerization Non-composite inorganic polymer flocculants such as ferric chloride (PFC), polyferric sulfate (PFS), and polysilicic acid are introduced into one or more of Fe3+, AP, Ca2+, Cl-, and S042-plasma during the synthesis process. Composite inorganic polymer flocculant. The reason why such flocculants have good flocculation effect is that it can provide a large number of polyhydroxy complex ions, and can strongly adsorb dirt colloidal particles, thereby promoting colloidal agglomeration through adhesion, bridging, and cross-linking. At the same time, physical and chemical changes have also taken place, neutralizing the charge on the surfaces of colloidal particles and suspended solids, which has decreased! Potential, colloid ions from the original phase repulsion into a suction, promote colloidal particles collide with each other, resulting in flocculent coagulation sedimentation. Therefore, a multi-type inorganic polymer flocculant can remove most of the suspended solids, disperse dyes, oxidized vat dyes, sulfurized dyes, and water-soluble dyes directly in the wastewater. When this flocculant is used to treat drinking water, the residual turbidity of water can be reduced to 2~3 degrees below (turbidity polymerization aluminum-polyacrylamide compound flocculant. This type of multi-element polymer flocculant is mainly based on polyaluminum chloride. Ingredients are prepared by introducing a certain amount of polyacrylamide (cationic, anionic derivatives) into a polyaluminum chloride system under 50-60 heating, atmospheric pressure, and strong stirring. The polymer bridging and synergistic effect principle to treat sewage flocculants compared to inorganic flocculants can reduce the amount of aluminum in water 24, which greatly reduces the toxic side effects of aluminum on human brain nerves. Artificially synthesized polymer compounds, there is no threat to human health due to toxic monomers generated due to incomplete synthetic synthesis.The presence of aluminum salt and iron salt in the flocculant at the same time, it increases the relative density, settlement speed, flocculation effect is remarkable.

Polyaluminum chloride-chitin complex flocculant. The Institute of Ecological Environment of the Chinese Academy of Sciences uses polyaluminum chloride as the main component to introduce a certain amount of chitosan into a polyaluminum chloride system under room temperature (or below 60°C heating), atmospheric pressure, and strong stirring conditions. Compounded into the above multi-flocculant E15]. The raw material chitin chosen by this flocculant is a natural organic macromolecule substance abundant on the earth, so it has great potential application value.

Comparing flocculant E with polyaluminum chloride (PAC) in actual use, its turbidity removal effect is shown in Table 4. Table 4 Comparison of turbidity of flocculant E and polyaluminum chloride Comparison of the concentration of pesticide (A1) / (mg.L(1) raw water turbidity/NTU residual turbidity/NTU flocculant E It is apparent from Table 4 that the turbidity of flocculant E is 48 times greater than that of using polyaluminum chloride alone, and the flocculation effect is good. .

Inorganic salt - cellulose compound flocculant. Liu Xing et al. have reported that a multi-type flocculant is compounded by an appropriate ratio of sulfonate, phosphate salt, lime, sodium silicate, sodium carboxymethyl cellulose, and the like.

Yang Heng et al. used the coagulation properties of polymeric aluminum and polymeric iron, the bridging adhesion of polyvinyl alcohol, and the removal of heavy metals from surfactant-mercaptotriazine (TMT15). , To make it into compound polymer flocculant Tang Hong. Development trend of inorganic polymer composite flocculants. China's water supply and drainage, Yu Gang, Yang Zhihua, Zhu Wanpeng, et al. The Status Quo and Development of Decolorization Technology of Dye Wastewater Zhang Yuejun, Gu Xuefang, Chen Weizhong, et al. Synthesis and Application of Cationic Flocculant PDA Journal of Nanjing University of Science and Technology, 2001, 25(2):205-209 Li Wende, Zhang Litian, Zhang Xinjian, et al. Advances in research of wastewater treatment technology of mercury-containing flocculants using starch starch phosphate as a flocculant Tang Ning, Chai Liyuan, Xiaobo Xiao (College of Metallurgical Science and Engineering, Central South University, Changsha 410083, China; mercury-containing wastewater; biological adsorption; biological enhancement; There are more than 80 industries that use mercury as raw material, and the use of mercury is as many as more than 3,000.(1) With such a wide range of uses, the amount of mercury that is lost to the environment globally is about 1.5xl04~3.0xl04t per year, with "exhaust gas, waste residue, waste water". Three ways to pollute the environment: Mercury and its compounds discharged into water bodies form various forms of mercury through physical, chemical, and biological actions and may even be converted into highly toxic methyl compounds. The disease is caused by the pollution of the waters of methyl chloride mercury emitted from chemical plants.

The hazards of mercury-containing wastewater have long been recognized by people, and a number of physical and chemical treatment methods have been developed. Hunan Province Science and Technology Plan Key Projects, No. -), 2004, graduated from Tianjin University of Technology, School of Material and Chemical Engineering, Master of Engineering. Phone: 022