| The study characterized the removal of strontium from an aqueous solution via coagulation coprecipitation followed by microfiltration (CPMF) with a lab-scale device. Sodium carbonate was used as the precipitating agent. Ferric chloride was added as flocculant. The concentration of strontium in the raw water used in this study was about 5 mg/L. In two intermittent tests, where dosages of sodium carbonate were 2000 mg/L and 1000 mg/L, respectively. The mean decontamination factors (DFs) were 237 and 158, and the mean concentration factors (CFs) were 302 and 462, respectively. Although the mean DF value was lower when the sodium carbonate dosage was 1000 mg/L instead of 2000 mg/L, the rate at which the specific flux (SF) of the membrane declined decreased as the amount of the effluent treated increased. The problem of strontium release at the beginning of the operation in the intermittent tests was solved by a continuous test in which the dosage of sodium carbonate still was 1000 mg/L and the other parameters were the same as that in the other tests. The results showed that the mean DF and CF were 157 and 480, respectively.Based on the lab-scale tests, the removal of strontium from an aqueous solution via CPMF with a pilot-scale device wes studied. The results showed that the mean DF was 130. The concentration of calcium and magnesium affected the scaling of tube mixer, sludge yield and membrane fouling very much. The concentration process was carried out without pressure. However, it is prospected that the residual sludge could be concentrated within 200 L with pressue in real application.Due to scaling of the pipe mixer on the pilot-scale test and bad effect of settlement in early stage of both the lab-scale and the pilot-scale experiments, Computational fluid dynamics (CFD) was adopted to compare mixing effect of stirrer with pipe mixer. And CPMF process was improved with pelleting method. The results showed that though the mixing efficiency of stirrer was lower than the pipe mixer in a unit time, the relative longer hydraulic retention time and stronger turbulent intensity made the general mixing effect of stirrer better than the pipe mixer. The improved process was primarily validated by pelleting experiments, which conducted by mixing with stirrer, adding crystal core and using sequential operation mode. The effect of sediment can be improved with turbidity reduced effectively. Therefore, the scaling problem of pipe mixer can be resolved by utilizing stirrer as the mixing and reacting device. Based on co-precipitation and membrane fouling mechanisms, the DF and CF of the liquid radioactive waste containing strontium will be improved by the new CPMF process.Due to poor biodegradability, complex components, high amount of total phosphate and ammonia, the scale inhibitor production wastewater is hard to treat. A hybrid microfiltration was used to treat the wastewater. The results of the experiments showed that the COD, TP and NH3-N of the treated wastewater were 174.8 mg/L,0.48 mg/L and 0.48 mg/L, respectively, which can meet the classⅢcriteria in the Integrated Wastewater Discharge Standard (DB 12/356-2008) in Tianjin。Coagulation–precipitation coupled with microfiltration was used to remove fluoride from groundwater. The amount of the water is 150 m3/d. When the dosages of aluminum sulfate were above 160 mg/L, the concentration of fluorine could be reduced to less than 1.0 mg/L from 2.52 mg/L in the raw water, and other main indexes were meet the demands of Standards for Drinking Water Quality (GB 5749-2006). The running cost is about 1.0 RMB per ton water. The simple flow and equipments provide a reference of design and running for modularization of defluoriding process, which is fit for countryside actuality.
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