Study On Sewage Treatment Using Immobilized Activated Sludge In Magnetic Field

Immobilization of microorganisms and magnetic technology are a hot research area in bioengineering, which have been used in many fields such as chemical industry and drug industry successfully. But there are very few reports concerning application of two technologies in dealing with the wastewater.In the study of this thesis, ultrafine magnetic Fe3O4 particles are prepared by co-precipitation. Activated sludge which adding activated carbon as adsorption and including magnetic Fe3O4 particles immobilized by the entrapment carrier materials of PVA (Polyvinyl Alcohol) and sodium alginate. In the self-designed reactor with the magnetic field which was put outside, the immobilized magnetic activated sludge micro-spheres was used to dealing with sewage .The results compared with the unimmobilized activated sludge indicated the method was effective and feasible.The optimized conditions which activated sludge was immobilized by the mixed carrier process using PVA as major entrapping material were studied. When the mixed carrier materials consisted of 8% PVA, 0.10% sodium alginate, 1:1 as the activated sludge amount; activated sludge : activated carbon= 10:0.25; magnetic Fe3O4 : activated sludge=1:100; the boric acid solution(pH=6.7)as coagulant including 2%CaCl2 and 24h as the optimum coagulant duration, then transferring micro-spheres into the 1 mol/LNaH2PO4 for 2h treatment, the magnetic beads with high magnetism and small diameter can be obtained. The electron microscopic observations also show better mesh structure.In this dissertation, the conditions such as temperature, pH, the different concentration of BOD5, continuous treatment, hydraulic retention time (HRT) et. were investigated by the use of immobilized magnetic activated sludge micro-spheres in wastewater bioreactor. And the satisfactory process parameters were obtained.