| Anthraquinone dying wastewater is one of the most refractory wastewater in dyeing industry. In this paper, the coupled process of Fenton oxidation and MBR was investaged to degrade the simulated Anthraquinone dye of X-BR water. It was found that the biodegradability of X-BR wastewater was improved and the toxicity was weakened. The pretreatment of Fenton oxidation was readily to create conditions for the subsequent bio-treatment. During the process of MBR, it was found that the dosing of ferric ions could ameliorate the sludge characteristics and the activity of microorganism. And also the membrane fouling was retarded due to the dosing of ferric ions.Firstly, when the X-BR concentration was fixed to be 100mg/L, the optimal parameters of Fenton oxidation were found to be H2O2=5.2mmol/L,Fe2+=0.52mmol/L and initial pH value=3. Under these conditions, about 99.9% color removal and 44.23% TOC (after the coagulation of ferric ions) removal ratio could obtain. By monitor the degradation of X-BR by FTIR and UV-vis spectra, it could be found that the chromophore of X-BR (anthraquinone group), was easily to be attacked by the generated hydroxyl radical (·OH) of Fenton oxidation. During the Fenton oxidation, the TOC degradation rate was far away lagging behind the decolor rate. In 40 minutes, the decolorization rate obtained was almost 99.7%It was sure that vast waste solids of Fenton sludge were produced during the application of Fenton reagent. The experiments were designed to recover the Fenton sludge to oxidation process as catalyst by the pretreatment of filtration and dehydration. Based on the recover of Fenton sludge, Fenton-like oxidation system was established. It was proved that the oxidation efficiency of Fenton sludge/H2O2 was slightly lower than that of classic Fe2+/H2O2 and Fe3+/H2O2. Compared with Fenton sludge/H2O2 and Fe2+/H2O2 system, TOC removal ratio gap was about 8%.Secondary, the synthetical evaluations of bio-degradability of X-BR solution and the products of Fenton oxidation were carried out by means of water quality of B/C index,aerobic respiration index and Zahn-Wellens-Test(ZWT). It was proved by the B/C index that X-BR solution was in the category of the most recalcitrant wastewater, while the B/C index of Fenton oxidation products was increased to a level of 0.25. According to different X-BR concentration of 50mg/L,100mg/L and 200mg/L, the corresponded aerobic respiration rate was 0.564 mgO2/(L·h),0.462 mgO2/(L·h) and 0.222 mgO2/(L·h), respectively. All the results were lower than that of endogenous respiration rate (0.708 mgO2/(L·h)). On the contrary, the aerobic respiration rate of the products of Fenton oxidation were higher than 0.708 mgO2/(L·h), which were 3.37 mgO2/(L·h),3.58 mgO2/(L·h) and 3.74 mgO2/ (L·h), respectively. It was proved by Zahn-Wellens-Test that the bio-activity of microorganism was severely obstructed even in the X-BR concentration of 50mg/L. And the Fenton oxidation products could achieve a degradation of about 78%. When the X-BR concentration were 25mg/L,50mg/L and 100mg/L, the light loss ratio of Vibrio fischeri were 17%,34% and 41%, respectively. As a contrast to the products of Fenton oxidation of initial X-BR concentration of 100 mg/L and 50mg/L, the light loss ratio were 10% and 6%.After the acclimation stage, the optimal parameters of MBR system obtained were MLSS=6000mg/L, DO=2.5mg/L, HRT=18hr. Based on these data, about 75% TOC removal ration and 27% TN removal ratio could be obtained. As for the three MBR system, different dosage of FeCL3 (MBR1:0%, MBR2:0.5%, MBR3:1%) were added to the aerobic system. The results revealed the followings. (1)There were big influence on the bio-activity of microorganism, and the dehydrogenase concentration of MBR1,MBR2 and MBR3 were 29,31,42μgTF/(mgMLSS·hr),respectively. (2)The dosage of ferric ions could enlarge the particle size and retard the membrane fouling. It was detected that the average particle size of MBR1,MBR2 and MBR3 were 76.2μm,92.3μm and 83.4μm, respectively. Besides, the dTMP/dt of MBR1,MBR2 and MBR3 were 0.592kPa/d,0.51 kPa/dt and 0.487 kPa/d, respectively. (3) Due to the inhibition effect of ferric ions on the secretion ability of microorganism, the EPS concentration was varied at 36.85mg/g(MBR1),31.2mg/g (MBR2) and 28.93(MBR3). It was also revealed that the Carbohydrate was reduced more significantly than protein. The adsorbed EPS concentration in cake layer of membrane was 2 fold of that in mixed liquor. (4) The ferric ions can reduce the sedimentation of organic substance on the membrane surface. The main membrane resistances were gel-polarization (Rp) and inner membrane resistance (Rif), which contributed about 80-90% of the total resistance. By the detection of FTIR and EDX methods, it was found that the main fouling substance of membrane was organic pollution. And the alkaline cleaning was the preferred cleaning method.Finally, it were introduced the desalination efficiency of the MBR effluent by reverse osmosis (RO) and a technology innovation for the dyeing wastewater plant by MBR process.
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