| The study was to investigate the factors that influenced the treatment effect of textilewastewater by UASB reactor. In the start-up period of UASB reactor, it took81days forsludge acclimation and66days for optimizing the factors that influenced the effect. Duringthe start-up stage, the pH, COD and color concentration of influent were set at the range of7.0-7.8,2000-3500mg/L and50-200mg/L respectively. The reactor was successfully activatedafter sludge acclimation, loading rate improving stage and high-loading-steady-running stage.In the third stage, the COD and color removal efficiency raised to82.7%and97.4%,respectively, the pH of the effluent kept stable at about7.6. From the data analysis, the highestremoval efficiency of COD and color was achieved when the pH, organic loading rate and dyeloading rate of the influent were8.0,5.25kg/m3d and0.3kg/m3d with a reflux ratio of3.0,which came to over90%and95%respectively. Meanwhile, properly low concentrations oftrace elements were essential for the reactor to keep a high and steady treatment effect. In thestudy, the influence of VFA and alkalinity concentration of the wastewater on effluent pH andreactor stability were discussed.The research employed a strategy of a transition from synthetic to real textile wastewaterwith five stages of debugging. At last, the COD and color removal efficiencies of realwastewater reached57.7%and79.3%, respectively. The biodegradability of the effluent wasimproved by the anaerobic process, with BOD5/COD (B/C) increased from0.251to0.382.Based on the data, periodic fluctuation of the concentration of total aromatic amine in effluentwas spotted during the real textile wastewater treatment stage, which might be a metabolite ofazo-dyes added in the process of textile. Besides, the cycle period of total aromatic amineremoval became longer than usual at strong basicity condition.By the determination of SVI, VSS, TSS, the particle diameter proportion of sludge andgranule settling velocity of five specific wastewater treatment stages, close relation was foundout between the settling property of sludge and the treatment effect. Cleas as we can find inthe data, when the removal efficiencies reached the hightest level, the SVI of decreased to thelowest level at11.6mL/g, while the VSS and VSS/TSS got to the top at55192mg/L and0.859,settling velocity achieved close to the highest at79.6m/h. However, SMA of anaerobic activated sludge kept at a hight level throughout the whole experiment, and reached the top at155.7mLCH4/g VSS d at the optimization stage, which reflected that the processing efficiencywas determined by the methanogens at some extent. Additionally, the tendency of Coconcentration variation in the dry sludge which was proved to be a critical factor tomethanogens activity by former researchers was similar to that of COD removal efficiency atdifferent treatment stages.The microbial diversity of anaerobic sludge was quite abundant throughout the study,while analogous and diverse population characteristics appeared in the granules of differentstages. Compared with the samples taken from the reactor start-up period, the communitystructure of the sludge of other operation processes changed in species and quantities but waskept stable as a whole. Besides, part of the sludge microbial community of dominant bacteriawas analyzed by cloning sequencing and phylogenetic analysis. Twelve bacterial16S rDNAsequences were identified, which got homology over90%compared with the bacteria ofClostridium sp., beta proteobacterium sp., Desulfovibrio sp., Lactobacillus sp., Thermus sp.,Selenomonas sp. and Thauera sp.. These dominant microorganisms played critical roles in theremoval of organic pollutants in the UASB reactor. |
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