Research On The Treatment Of Wastewater With Supported Metal Strengthening Zero-valent Iron System

With the rapid growth and urbanization of the industry, chemicals are widely used and increase dramatically worldwide, many nonbiodegradable substances discharged into the water would have devastated human and ecosystem. Zero-valent iron(ZVI) technology shows promising prospects in wastewater treatment. This project mainly study strengthening ZVI wastewater treatment Efficiency by preparing a kind of loaded metal. Under the background that complex industrial wastewater treatment with the traditional zero-valent iron technology is not ideal.First, 200mg/L methyl orange simulated wastewater was experimented with zero-valent iron and the loaded metal under different loading conditions together. The results showed that:the best methyl orange simulated wastewater treatment was under the condition that the extruded mesoporous MCM-41 zeolite loaded with 5% cobalt nitrate impregnated at room temperature for 12 h and dried at 120℃ for 6h and then calcinated at 400℃ for 4h. Under this conditions, the decoloration rate and COD removal rate of methyl orange simulated wastewater was up to 83.6% and 76.8%.with the treatment of Co/MCM-41 strengthen ZVI system.Secondly, the optimum reaction conditions of methyl orange simulated wastewater treatment with Co/MCM-41 strengthen ZVI system was studied, It turned out that the decolorization rate and COD removal efficiency reached 93.2% and 88.2% when the dosage Co/MCM-41 was 1g, reaction temperature was 30℃and the influent pH was 3. Co/MCM-41 strengthened the zero-valent iron to have a wide range of application pH and better treatment effeciency for wastewater treatment. The fitting result of the methyl orange decoloration implied that the kinetics of the wastewater degradation with Co/MCM-41 strengthening zero-valent iron was nearly second order. Co/MCM-41 could decrease the apparent activation energy of the reaction for 19% and improve the treatment effeciency of the wastewater. It wasfound that the zeolite treated with extrusion and loading metal could keep the long-range ordered structure of MCM-41 and the cobalt oxide had monolayer dispersion on MCM-41 zeolite proved by X-Ray Diffraction(XRD) and Nitrogen Adsorption method. Cobalt had been supported on the MCM-41 zeolite, and formed Co3O4. In addition, methyl orange simulated wastewater treatment with Co/MCM-41 strengthening ZVI system was completed probably by adsorption, the treatment of hydroxyl radicals, Co/MCM-41 catalytic reaction of oxygen and cobalt metal catalyzing hydrogen peroxide together.Finally, the reverse osmosis concentrated wastewater treatment with Co/MCM-41 strengthen ZVI system was studied. The orthogonal experiment designed basing on single factor testresulted that the removal rate of COD was up to 54% when the reaction time was0.5h, initial water pH was 5, the reaction temperature was 20℃, the amount of iron was 5g and Co/MCM-41 dosage was 3g and the reaction time was the most important factor affecting COD removal. Besides, removal rate of UV254 was up to 50.7% on the condition that the reaction time was 1.5h, initial water pH was 3, the reaction temperature was 20 ℃, the amount of iron was 5g and Co/MCM-41 dosage was 4g and the initial pH was the most important factor affecting UV254 removal. Compared with the wastewater treated by iron scraps separatedly, the presence of Co/MCM-41 played an important role in strengthening zero-valent iron/oxygen system and improving the biodegradability of the wastewate.