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Treatment of membrane pollutants in high salt wastewaterThe new sewage treatment process combining membrane separation and biological reaction has the advantages of small footprint, good effluent quality, and low sludge production. In recent years, it has attracted widespread attention and gradually been applied to the treatment of urban and industrial wastewater [1,2] With the continuous deepening of MBR research and the expansion of its application scope, MBR has begun to be applied to the treatment of high salinity wastewater Sun et al. [3] used MBR to treat high salt wastewater in industrial areas, and found that the volatile solid content (VSS)/solid content (SS) of MBR sludge in long-term operation was about 0.4, the chemical oxygen demand (COD) removal rate was 80%~95%, and the removal rate of ammonia nitrogen (NH+4-N) was 95%; Pendashteh et al. [4] used sequencing batch reactor (MBR) to treat high salt oily wastewater. Multiple organic loads, hydraulic retention time (HRT), and total dissolved solids (TDS) were selected for experiments. When the COD load was 1.1 kg · (m3 · d) -1, HRT was 48 hours, and TDS was 35 g · L-1, the COD removal rate could reach 97.5%; Jang et al. [5] observed that when the salinity of saline wastewater was increased from 5 g · L-1 to 20 g · L-1 using MBR, the removal efficiency of NH+4-N decreased from 87% to 46%, while the removal efficiency of dissolved organic carbon (DOC) was not affected; Artigaa et al. [6] used suspended packing MBR to treat high salt wastewater generated during the production of canned tuna. After 73 days of operation, the activated sludge adapted to a salinity of 84 g · L-1, and the COD removal rate reached 92% Zhang Yushan et al. [7] used MBR technology to treat seawater for toilet flushing. After microbial domestication, when the proportion of seawater in the wastewater did not exceed 48%, the removal rates of COD and NH+4-N reached 86% and 93%, respectively, but the sedimentation performance of the sludge deteriorated Membrane fouling has always been a technical obstacle that restricts the application of MBR technology It is generally believed that soluble microbial products (SMP) and extracellular polymeric substances (EPS) are the main organic components of membrane pollutants, including sugars, proteins, and humic acids At the same time, the inorganic pollution on the membrane surface has also received extensive attention. Wang et al found that the gel layer formed by the deposition of inorganic substances composed of Mg, Al, Fe, Ca, Si and other elements on the membrane surface and the combination of organic substances is an important reason for membrane pollution Meng et al. [11] found that the bridging effect between inorganic compounds and biopolymers can make the membrane fouling layer more compact, thereby exacerbating membrane fouling Huang Xia et al. [12] used field emission scanning electron microscopy to observe the surface of PAC-MBR membrane after pollution, and found many regular and angular square pollutants. They analyzed them and found that they were inorganic scale bodies, mainly composed of CaCO3. Fu Wei et al. [13] found that there were elements such as Na, Mg, Al, Si, Cl, Ca, Fe, Mn on the membrane surface of MBR reactors under long-term operation, and believed that acid cleaning could remove most of the inorganic membrane pollution At present, research on the characteristics of membrane surface pollutants mostly uses domestic sewage or distribution water as MBR influent, which has a high content of organic components and a much lower content of inorganic components than organic components. There is still relatively little research on the characteristics of membrane surface pollutants in MBR treatment of high salt wastewater conditions In this experiment, water distribution (simulated high salt wastewater) was used as MBR influent, and the MBR operated stably for more than 121 days under the condition of low organic load. The removal effect of MBR on influent organics and NH+4-N and the change of sludge properties were concerned. The characteristics of membrane surface pollutants of MBR under the condition of treating high salt wastewater were studied by means of scanning electron microscope X-ray energy spectrometer, gel filtration chromatography, Fourier infrared spectroscopy and three-dimensional fluorescence spectroscopy, so as to provide useful information for further exploring membrane pollution control measures |
