Low Concentration Cesium-containing Wastwater Treament By An Adsorption-microfiltration Combination Process

Good decontamination of cesium can be achieved by the combination of theadsorption and microfiltration used for simulated waste water treatment. The maincontent of this paper was to research on the adsorption-microfiltration combinationprocess for the treatment of low concentration wastewater containing cesium. Copperferrocyanide (CuFC) was used as the adsorbent. The test was divided into two stages.In the first stage, a single-stage adsorption-microfiltration was used for cesiumremoval; in the second stage, a countercurrent two-stage adsorption-microfiltrationwas studied to remove cesium ions from the simulated wastewater, in which the rawwater contacted with the old adsorbent that retained adsorption capability firstly. Thenthe new adsorbent was dosed and the cesium concentration decreased again. Finally,the0.22μm hollow fiber membrane was used to separate the adsorbent from theeffluent.In the first stage, when the dosage of CuFC was40mg/L, the average effluentcesium concentration was0.2296μg/L, the average decontamination factor (DF) was463, and the concentration factor (CF) was1648. When the adsorbent dosage was80mg/L, the average effluent cesium concentration was0.0753μg/L, the average DFwas1374, and the average CF was722. However, when the dosage of CuFC was80mg/L, after the end of the test, the residual sludge volume in the reactor was larger.It could lead to the difficulty for following treatment. Therefore, in the second stage ofthe test, the adsorbent dosage of40mg/L was chosen. The DF and CF of the test couldbe got through choosing the optimum value of process parameters.In the second stage, the concentration of cesium in the raw water was about100μg/L and pH values of the raw water were about7.67, and pH values of theeffluent water were about8.12, the turbidity maintained below0.08NTU. In this paper,the research of different dilution factors (F) for treatment of wastewater containingcesium was carried out. It was found that, when the F was0.7and the dosage ofadsorbent was40mg/L, the mean removal rate of cesium was99.83%, the average DFwas582. The mean removal rate of cesium was99.90%and the average DF was948when F was0.4at the same conditions. The results were better than that obtainedfrom F=0.7. Different F values have little effection on pH and turbidity while effluentcesium concentration was lower when F decreased.