| Conventional membrane bioreactor(MBR) systems have increasingly been studied in recent decades. However, their applications have been limited due to their drawbacks such as low flux, membrane fouling, and high operating cost. There are few research on MBR which was applied to real mariculture wastewater currently, and this study attempts to find a new type of composite membrane technology which can slow the membrane fouling effectively as while can obtain better effects of mariculture wastewater treatment.In this study, a new process for combining biological contact oxidation(BCO) with MBR was established. The combined system was compared with the conventional MBR with respect to the performances of mariculture wastewater treatment, the membrane fouling and the characteristics of mixed liquor under different parameters. Fluorescence excitation emission matrix spectroscopy(EEMS) was used to study the impact of biological contact oxidation process on the soluble microbial products characteristics, thus to explore the process of membrane fouling of BCOR-MBR in mariculture wastewater treatment.First, the performances of BCOR-MBR treatment were analysed. Results showed that the average removal rate of TOC, ammonia nitrogen, phosphate by the BCOR-MBR process under different salinity wastewater were 92.69%, 95% and 22.4% respectively, and the treatment effect was better than the control group. The salinity impact can produce great influence on poly-P bacteria. BCOR-MBR with hydraulic retention times(HRT) of 8 hours and solids retention time(SRT) were proven for its best ability to treat mariculture wastewater, when the average removal rate of TOC, ammonia nitrogen, phosphate were 95.49%, 96.09%, 29.16% respectively.Under the condition of constant flux, the TMP of control group rose obviously faster than BCOR-MBR, illustrated that coupling with the BCOR process alleviate the membrane fouling in a certain extent. Based on the sludge characteristics and microbiological metabolic product of these two sets of MBR comparison, discovered lower sludge accumulation and better activated sludge settling performance in the BCOR-MBR. SMP gradually accumulated and the value of p/c in a rising state in BCOR-MBR, due to the role of return sludge from MBR to BCOR, EPS concentration is much lower than the control group and p/c is relatively low, shows that coupling with BCOR can reduce membrane pollution.The analytical of microbial products characteristics results showed that the salinity impact could enhance the microbial resistance, and the macromolecular protein output increased which were needed to participation the permeation in cells. In the combination of membrane technology, suspended particles and macromolecular organic matter will first adsorption on the BCOR packing or broken down into small molecules soluble substances, thus delayed the salinity impact to some extent. Fluorescence spectra of effluent water illustrated that humic-like acid material and soluble microbial products were intercepted by the membrane filtration function, and the interception for humic-like acid is stronger than soluble microbial products.Extrapolating from the correlation analysis, the EPS did not reach enough concentration and viscosity to cause formation of cake layer rapidly, and the SMP with higher protein content accumulated gradually, part of SMP flowed into effluent water through the membrane surface, the rest of SMP adhered on the membrane with the sludge flocs and colloidal substances, membrane pore jams gradually, the structure of filter cake layer is relatively loose because of less EPS adhered on the surface of the membrane, as a result of it can be fell off easily under the action of shear force by aeration.The rapid fouling in BCOR-MBR occurred until the cakelayer porosity reduced and accumulated to a certain thickness. |
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