The Preparation Of Poly-silicate-sulfate-zn-fe Flocculant And Application In The Algae Water

Algae pollution is more and more serious with the aggravation of the water eutrophication problem. The pollution of algae and its byproducts brings many adverse impact to the traditional water treatment process, increases the difficulty of water treatment, and it makes the safety of water supply can’t be guaranteed. Development a technology which can remove the harmful algae directly in the water source region becomes a hot focus, coagulation is a chemical method to remove algae, this method does not destroy algal cells and do not produce disinfection by-products, therefore it’s a kind of method to remove algae in high security. And composite flocculant is considered to be one of the future development directions of flocculant. This research using a large number of Fe SO4·7H2O which is the by-product of titanium dioxide and Zn SO4 as the raw materials, adopts the copolymerization method to prepare poly-silicate-sulfate-Zn-Fe(PZFSi C) coagulant. The main research contents and conclusions are as follows:1) the preparation of poly-silicate-sulfate-Zn-FeStudy the effect of p H, active temperature, concentration of Si O2 on the gelation time of polysilicic acid; Parameters affecting the coagulant performance such as the preparation time,reaction temperature, n(Fe)/(Si), n(Fe)/n(Zn), n(OH)/n(Fe) in this study, were examined. The results show that the best preparation conditions for polysilicic acid is p H = 5, Si O2 concentratio=2.5%, the active temperature is 25 ℃; Optimum conditions for the preparation of PZFSi C: n(Si)/n = 1/6(Fe), n(Zn)/n(Fe) = 1/9, OH/Fe = 0.3. As the Dose amount is larger, the better the treatment effect, when the dose amount is more than 20 mg/L, the residual turbidity belows 2NTU, the removal of UV254 over 90%, considering the economic factors, choose the best additive quantity of 20 mg/L.2) the characterization and morphology of poly-silicate-sulfate-Zn-FeUsing FT-IR, XRD, SEM and UV /Vis analytical methods for characterizing the structure of the product, timed spectro-photometry of Fe-ferron complexation was used to study morphology of PZFSi C. FT-IR analysis shows that Fe(III) 、Zn(II) and Si connected though the-O- or-OH and formed branched or mesh structure which enhance the flocculating ability; the UV/VIS analysis shows that the higher the Si/Fe ratio, the more species generated which is hard to hydrolyse; the disappeare of the derivative peak of zinc sulfate and ferric sulfate in the XRD pattern, and the appear of the amorphous package when the 2θ= 10~35°, suggests that PZFSi C is a new polycrystal compounds which contains of zinc, iron and other polymer, rather than the mixture of raw materials simply. The SEM analysis shows that the coagulant structure is tightly which is fold and intersect to form a high polymerizate and block structure macromolecular material, its adsorption sweep ability is strong, the formation of flocs is big and close together, the coagulation effect is good. n(Si)/(Fe) has a great influence on the distribution of iron morphology, when the n(Si)/(Fe) =1/6, the content of effective component Feb is highest, so the flocculation effect is best; With the increase of ratio of OH/Fe, the content of Fea is decreasing gradually; Feb content reach the maximum 19.43% when the OH/Fe = 0.3, the content of Fec increased gradually with the increase of the ratio OH/Fe.3) the application of poly-silicate-sulfate-Zn-Femake a comparison of conventional coagulants and PZFSi C coagulant using the simulated water and the actual water, Respectively. Explore the influence of various factors on the coagulation effect of PZFSi C. Using the PZFSi C in the treatment of simulate water, The results shows that when PZFSi C dosing quantity is 30.0 mg/L, the processing effect is best, the best turbidity removal rate can reach 95.8%, UV254 removal rate was 87.5%, the chlorophyll removal rate reached 98.7%; When the p H of water between 6 to 9, the coagulation effect is best, and PZFSi C adapts to a wide range of temperature. With the comparison of PFS, APAM, APAM- PZFSi C, its processing effect is PZFSi C > PFS > APAM- PZFSi C > APAM, PZFSi C coagulation effect is superior to other three kinds of coagulants. For chongqing water which containing algae water, applies PZFSi C natural algae in water, the optimum dosing amount of 30 mg/L, the dose is bigger than treatting simulate water, that’s mainly due to the natural water is more complex than the simulate water, which have more organic matter. compared with PAC, PZFSi C is a slightly superior to PAC in removal of ammonia nitrogen, CODMn, chlorophyll, but PAC dosing amount to less than PZFSi C.