| The decolorization and treatment of industrial dye wastewaters is difficult and costly. Sine white-rot fungi can degrade a series of toxic substances including dyes, the use of them to treat dye wastewater by bioaugmentation has been a focus recently. And the efficient microbial screening is the key in this field. A strain of fungus, Phanerochaete sp. HSD, which has the ability to acclerate aerobic granule formation and to degrade dyes, was screened in our lab in Collage of Life Sciences, Henan Normal University, China. In this thesis, the applications of MnP secreted by strain HSD in dye decolorization and aerobic granulation by bioaugmentation in the process of wastewater treatment were investigated.The influence of carbon and nitrogen sources on the production of MnP was analyzed using the nutrient-limited media. The important factors, Mn2+ and diammonium tartrate, affecting the production of MnP was screened by the initial screening method of fractional factorial design, and the effects of important factors on MnP production were studied by a full factorial central composite experimental design. Diammonium tartrate and Mn2+ concentration were chosen as two independent variables, and MnP produced by P. sp. HSD was the dependent response. Data processing was carried out on Minitab 15 software, and a quadratic polynomial was regressed. Optimum operational parameters can be obtained by solvingthe second order polynomial regression equation. The corresponding maximum MnP activity (2606 U/l) was obtained when the values of diammonium tartrate and Mn2+ were 0.628g/l and 52.2μmol/l, respectively, this yield is 247 % higher than that of before optimization.MnP produced by Phanerochaete sp. HSD showed a significant decolorization to Congo red, methyl orange and Eriochrome black T. For 120 and 350 mg/l of Congo red, 95% decolourization rate was observed at the 5th and 8th hour; for 200, 350 and 600 mg/l methyl orange, 95% decolourization ratewas obtained at the 5th, 6th and 9th hour. Furthermore, the decolourization rates of 150 and 300 mg/l of Eriochrome black T were up to 97.1 % and 91.4 % at the 7th and 13th hour, respectively. Ultraviolet - visible analysis shows that the decolorization of the three dyes is due to the cleavage of their azo bondsA high concentration of manganese ion in the medium has a significant impact on biomass, hyphae and mycelial pellet morphologies of strain HSD. Higher manganese ion concentration can inhibit the growth of hypha, resulting in a decreasing trend in biomass. When manganese ion concentration in medium is 2.00 mmol/L, the diameter of micro-mycelial pellets reaches the minimum value, but the number of them is up to the maximum. At the same time, under the condition of high manganese ion concentration, micro-mycelial pellets are composed of a large number of chlamydospores. Thus, MMPs which include lots of chlamydospore is a kind of new biological agent. The phenomena of the miniaturization of micro-mycelial pellets and overproduction of chlamydospore under the condition of high manganese concentration are interesting and have important value in the application of bioaugmentation technology. Aerobic granular sludge was domesticated using the MMPs in SBR. After 2 -week domestication, aerobic granular sludge (biological bioaugmentation aerobic granule, BAGs) was successfully cultured. The MMPs were tracked by the color of crystal violet, and the results showed that aerobic granule was developed on the bais of a primary core, the MMP. The acclerated sludge granulation by the MMPs can be explained from the two aspects: (a) serving as the cores, MMPs is developed to be the bigger granular sludge directly; (b) MMP is incompact pellet and it consists of quantities of chlamydospores. The detached chlamydospores from pellets can form new pellets in the reactor, and the newly formed pellets also can present the nucleus for granule formation.Thus, MMP is a kind of good carrier and can be used for the accerlation of sludge granulation.The feasibility of treating EBT wastewater by the BAGs was studied in SBR. When the influent EBT concentration is 400 mg/l, decolourization rate was 78.2 % after a 6-h treatment. By the hour 10, the EBT was biodegraded completely. The removal efficiency of BAGs is better than conventional activated sludge and conventional aerobic granule, indicating that it is feasible to treat dye wastewater by the bioaugmentation granular sludge reactor. The treatment of dye wastewater by the BAGs augmented by MMPs is a specific bioaugmentation process, worthy of further study and application in the treatment process of real dye wastewaters. |
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