| In recent years, traces of antibiotics have been found in waters, including surface water and groundwater, which posed a threat to human health. Constructed wetland as a new technology is widely used for sewage treatment, and much attention has been paid to the study of artificial wetland substrate material too. Considering the photochemical stability, non-toxic, photocatalytic excellent performance features of Ti-bearing blast furnace slag, use Ti-bearing blast furnace slag as substrate of constructed wetland to deal with wastewater containing antibiotics, and study characteristics of Ti-bearing blast furnace slag in purification of antibiotic wastewater through the experiments. Its research is expected to not only have positive effect on the study of constructed wetland purification in wastewater containing antibiotics, but also is expected to achieve high value-added resource comprehensive utilization of Ti-bearing blast furnace slag, which has important environmental, economic and social benefits. The main research content in this paper is as follows:(1) By studying the influence law of different pH and time on leaching elements of Ti-bearing blast furnace slag, sentenced the influence of leaching conditions on leaching element content. Synthesized the optimum leaching conditions of various elements, and achieved the leaching conditions suitable for plant growth. Conclusion is as follows:Within normal water pH range and artificial wetland hydraulic retention time range, no harmful heavy metal elements leaching, the elements leaching:Ca、 M、Si and S have a good effect on plant growth; Synthesized pH’s influence on the leaching of various elements, weak alkali conditions are conducive to some beneficial elements’ leaching; The leaching amount of most element which are beneficial to plant grows as time increases, while content of aluminum which is harmful to plant reduced as time increases, therefore, under certain conditions, for Ti-bearing blast furnace slag which applied to the constructed wetland as matrix, increasing time of leaching benefits the growth of plant.(2) Using Ti-bearing blast furnace slag as photocatalytic materials, investigated photocatalytic degradation effect of Ti-bearing blast furnace slag on different antibiotics, and found good antibiotics as target degradation content. Studied the adsorption and photocatalytic degradation properties of Ti-bearing blast furnace slag on the target degradation content, explored the best reaction condition parameters, and explored the degradation pathways of the target degradation content. The conclusion is as follows:The photocatalytic effect of Ti-bearing blast furnace slag on ciprofloxacin is better than that on norfloxacin and ofloxacin. Langmuir equation expressed can be used to express the optimal isotherm models of ciprofloxacin adsorption for Ti-bearing blast furnace slag. The first order kinetics equation can be used to express the dynamic model, suggesting that the adsorption process is mainly controlled by physical adsorption. The optimal reaction condition parameters:when slag dosing quantity 60mg/ml, light intensity 2.25mW/cm2, illumination time 3h, the volume 50ml, the ciprofloxacin concentrations 10 mg/L, the total removal rate of ciprofloxacin solution was 82.22%, the photocatalytic degradation rate was 7.96%, accounting for 9.68% of the total removal rate, and adsorption is dominant. Photocatalytic degradation of Ti-bearing blast furnace slag ciprofloxacin path is divided into the following two kinds:path one is a N-alkylation process, after two step hydrolysis, oxidation product M-2 generated to part of alkylation products M-26, the oxidation products M-26 continue to be oxidized, forming a completely out of alkylation products M-69. Path two is an oxidation process of cyclopropyl, hydroxylation and alkylation reaction was taken in the first place in piperazine ring of enamine, and then cyclopropyl was oxidized to allyl or acetyl two oxidation products (i.e., M+2).(3) Explored the effect of the influencing factors on wastewater purifying and purifying of sewage containing antibiotic with Ti-bearing blast furnace slag treatment, and found the best sewage purification process parameters. The results showed that in Ti-bearing blast furnace slag treatment of sewage, the removal rate of COD ranges of 16.21% to 54.29%, the removal rate of TN ranges from 8.36% to 40.46%, the removal rate of TP ranges from 84.92% to 94.97%, and the light had no obvious effect on sewage purification. In Ti-bearing blast furnace slag treatment of sewage containing antibiotics, because of the competitive adsorption between ciprofloxacin and the nitrogen and phosphorus inorganic salt and other organic matter in sewage, the CIP adsorption ability of Ti-bearing blast furnace slag reduced. Small molecule of ammonia nitrogen taken off into the water in the process of alkylation of Ciprofloxacin increased the nitrogen content in the water, leading to the reduction of the removal rate of TN. When slag dosing quantity 60mg/ml, illumination time 4h, the light intensity 2.25mW/cm2, pH 7, the volume 50ml, the antibiotic concentrations of which is 10 mg/L, the removal rate of COD, TN, TP, CIP were 55.98%,41.66%, 96.97% and 41.66% respectively. |
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