| In recent years, with the gradually adjustment of the agricultural structure and the agricultural industrialization of livestock and poultry breeding industry, livestock wastewater discharge brought about a large number of environmental problems, becoming an important pollution source,besides the industrial wastewater, domestic sewage Livestock and poultry waste water have the properties of high suspended solids, high organic matter and high ammonia nitrogen and other characteristics, So how to solve the livestock farm wastewater treatment especially for the high ammonia nitrogen removal has become an important topic. Immobilization of activated sludge wastewater treatment can prohibit microbial loss and maintain high efficiency biological concentration that is capable of ensuring the efficient processing, at the same time, low sludge production, can be repeated use of such advantages. Shortcut nitrification denitrification can effectively reduce the external carbon source and aeration rate; meanwhile, it also achieve stable operation, low cost, simple and convenient operation and other advantages in handling high strength ammonia wastewater.This experiments, using immobilized entrapped activated sludge technology mature, combined with the shortcut nitrification denitrification reaction mechanism of theoretical basis, by the national standard method for the determination of the index of water quality, studied in continuous operation mode of each factor to the entrapped particles shortcut nitrification-denitrification process, and explores the achieve high efficiency of single factor condition.The immobilization methods utilize combined, adsorption, embedding method, covalent binding and cross-linking method, which is the most common application of embedding method.Embedding method has the advantages of simple operation, small impact on microbial activity, produced by the immobilized microorganism high strength.Through the experience of the comprehensive comparison, using polyvinyl alcohol (PVA) embedding method for preparation of immobilized activated sludge granules, and adding sodium alginate (SA) as an additive to increase the mechanical strength and to improve the particle mass transfer performance, adding powdered activated carbon as adsorbent, increasing microbial adsorption.The experimental results showed that, the method is easily available raw materials, low cost, simple and easy operationthe preparation of the ball better toughness, the stamping deformation is not easy broken, mass transfer effect is good, is an ideal immobilization method.The factors influencing the embedding conditions of PVA, SA, powdered activated carbon and sludge concentration and embedding agent quality than (referred as the embedding ratio) was determined by the orthogonal test, each factor selected from three levels, use L9(34) orthogonal experiment, the experimental results show that PVA embedding method of optimal conditions for A2B2D1C3, the PAV is8%, SA is0.4%, powdered activated carbon was0.5%, embedding ratio1:2.According to the orthogonal experiment the best embedding ratio,, and through active recovery experiments make the entrapped particles to the reactor interior environment.After a week of activity recovery experiment, immobilized on COD and ammonia nitrogen removal effect tends to become stable, the COD removal rate reached75.57%, the removal rate of NH4+-N was found to be70.33%Choosing livestock wastewater as aobjective, the study controlled the hydraulic retention time HRT, dissolved oxygen (DO), pH value, temperature, carbon-nitrogen ratio C/N and other major single factor, respectively, which influence nitrosation, in order to make immobilized activated sludge particles achieve stable shortcut nitrification-denitrification, under a continuous flow operation mode for wastewater treatment. The results showed that when a single factor HRT is10h, dissolved oxygen is4mg/L, pH value is8.5, temperature is30℃and carbon-nitrogen ratio is10, the TN and COD removal rates were81.98%,93.79%;87.32%,98.35%;83.82%,93.93%;85%,97%;85.37%,97.28%, respectively, which achieved the desired removal efficiency. As long as the external environment is properly controlled, the internal particle of nitrifying bacteria and denitrifying bacteria in natural competition can also maintain advantage and a large number of breeding for high efficiency flora.Therefore the common activated sludge immobilization for the treatment of livestock wastewater, can quickly adapt to the environment and achieve quick start, is an economical, practical, and feasible way. |
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