Photosynthetic Bacteria And Fe(Ⅱ) EDTA/H₂O₂ Electro-catalytic Degradation Of Dye Wastewater

With rapid development of dyestuff industry, the variety and quantity of dyes are continuously increasing, which leads to increasingly severity on the pollution problem of aquatic environment. It becomes a worldwide difficulty and hotspot to research the decoloration and degradation of dye wastewater, which is also an important subject in environment protection research.The dye wastewater, which featuring complicated organic matters, high concentration, high chroma, vast quantity, heavy toxicity and large disposal hardness, is difficult to be degraded by aerobe and may be deoxidized into carcinogenic aromatic hydrocarbon amines at anaerobic conditions. Conventional methods, such as adsorption, flocculation and biological oxidation technology, generally can not achieve the goal of purification.In this research, the method of purple non-sulfur photosynthetic bacteria and that of Fe(II) EDTA/H₂O₂ electro-catalysis are taken respectively to investigate the degradation characteristic of methyl orange which is taken as the research object. The main investigation content is as follows:(1) Take active sludge from some sewage treatment plant as the material, screen out the photosynthetic bacteria and get the pure culture by purification, then take which as the foundation for expanded cultivation. With domestication cultivation, factors that affect growth and propagation of the photosynthetic bacteria such as temperature, dissolved oxygen, photo illumination, pH and different carbon sources were studied, and a sort of associate strain that has specifically degradation effect on dye wastewater has been brought up. The study indicates that the stationary growth stage of purple non-sulfur photosynthetic bacteria is on the next and third day. Furthermore, these bacteria can live in the pH range of 6 to 9, and 6.8 the best. They can utilize various kinds of carbon sources but sodium bicarbonate, while glucose is benefit for their growth.(2) Conventional Fenton Method was improved. The wastewater dealt with the above method of photosynthetic bacteria was disposed by Fenton-like reagent combined with electro-catalysis means, and the COD and chroma of which are wiped off so that the effect on wastewater degradation was advanced. Besides that, the oxidation characteristic of Fe(II) EDTA/H₂O₂ combined with electro-catalysis system for disposing dye wastewater was approached, which established the theoretical basis for researching the effect of Fenton-like reagent on catalyzing and degrading other dye and indicator system in neutral or alkaline conditions. The result indicates that the appropriate pH value for catalyzing and degrading methyl orange simulated wastewater by Fe(II) EDTA/H₂O₂ is 6.5. In the condition with EDTA/Fe²⁺ of 2:1 (molar ratio, with Fe²⁺ of 40.0mmol/L), H₂O₂ of 48.0mmol/L and initial concentration of 260mg/L, after 90 minutes electrolysis for the methyl orange solution, the decoloration rate of methyl orange can reach 78.0% and the CODcr to 80.0mg/L. What's more, the result indicates that the characteristic functional groups in methyl orange's molecular constitution are broken in the process of electro-catalysis and degradation for methyl orange wastewater by Fe(II) EDTA/H₂O₂. EDTA in the experimentation is the catalyzer as well as the reactant, which effectively avoids the possibility of secondary environmental pollution by EDTA and spreads the field of application of Fenton-like reagent. EDTA approaches to comprehensive potential application consequently.