| Due to high COD concentration, heavy color, and low degradability, dyeing wastewater is one of the refactory wastewaters, the process that is more advanced, lower cost and better treatment effect is needed. A novel ACF-MBR was used for high concentration dyeing wastewater in this research, which is a perfect combination of the membrane filtration and the activated sludge process. Itcan also reduce energy consumption. This study aims at providing a theoretical suport for that the new ACF-MBR process being better to beused in engineering application, reduce membrane fouling, and choose the appropriate membrane module according to different process conditions. During the experiment, it changes the reflux ratio, MLSS.aeration intensity, and add hydrolysis acidification tank in the range of the operation time123days. Water quality, membrane flux, sludge characteristics, membrane resistance, and other parameters under different conditions were meausured to research the influence of the operating conditions and the sludge features on the treatment efficiency of MBR and the membrane fouling of hollow fiber membrane and flat membrane. The concentration of proteins and polysaccharides in mixed solution were measured, and the correlation between the composition of EPS and membrane resistance was discussed with EPS abstracted by disodium EDTA method. Thezeta particle,VSS and SS were also measured, and the correlation between the zeta particle of EPS.cake layer and MLSS ingredients and membrane resistance was discussed.Main conclusions were made as follows:(1) During the experiment, the CODCr-removing effect of hollow fiber membrane is better than that of flat membrane, the water out of the two membranes has no gap on color. Two kinds of micro-filtration membrane can play significant retention effect on organic matters.(2) After the addition of hydrolysis acidification tank, CODCr and color removal efficiency are significantly improved. With the increase of reflux ratio, the processing efficiency of CODCr has a rising trend. When using ACF-MBR alone for dyeing wastewater treatment, color removal efficiency reduce with reflux ratio increasing significantly. Discharging sludge make the CODCr of out water decline slightly and have little effect on the chroinaticity. Too high or too low aeration intensity will result in the increase of out water CODCr, color removal efficiency increases with aeration intensity increasing.(3) Analyzing membrane flux attenuation, the greater the initial flux is, the sooner the flux decays. The flat membrane has a higher flux than hollow fiber membrane. Analyzing membrane resistance, the membrane resistance and its increase rate of the hollow fiber membrane is significantly higher than that of flat membrane.Gel cake layer membrane resistance of two membranes accounted for more than98%of the total resistance, and they can restore the whole flux basically through physical cleaning.(4) The higher reflux is, the more slowly the membrane fouling, especially for the flat membrane. It shows a linear relationship between the membrane resistance increase rate and MLSS basically. It presents good negative linear relationship between the membrane resistance increase rates of two membranes and aeration intensity and the linear slope of hollow fiber membrane is greater than that of flat membrane.(5) It shows a significant relationship between sludge viscosity and the membrane fouling, monitoring results demonstrate Pearson coefficients rp between sludge viscosity and the resistance of hollow fiber membrane and flat membrane respectively, is0.974and0.937. Analyzing SEM of membranes comparatively, the mask holes of new flat membrane are more uniform and can form denser cake layer. The inner supporting layers of the hollow fiber membrane have no obvious contaminants after contamination.(6) The values of PR/PO and EPS/VSS in the cake layer of hollow fiber membrane are higher than that of flat membrane and MLSS generally.The PR/PO of EPS is above the SMP largely. It reveals similar strong correlations between the EPS and PR/PO in cake layers and their Rf respectively.It shows a strong negative correlation between zeta particle size of the cake layer EPS and two membrane resistance, especially for hollow fiber membrane.(7) Increasing the reflux ratio, reducing the sludge concentration and increasing aeration intensity all can result in the reduction of PR/PO and EPS/VSS in MLSS and two membrane layers, which corresponds to the relationships between operating conditions and various components and the membrane fouling. |
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