Abstract There is often a need to improve the taste of mineral water by reducing the sulphate ion content. It was found that for such an effect, nanofiltration (NF) process can be used. In the case, the proposed formula was assumed obtaining a mineral water with reduction of H2S and SO42- content through the following processes: stripping - UF/MF or rapid fi ltration - nanofiltration - mixing with raw water or filtration through calcium bed. The paper shows the results of the tests, with use of mineral waters and nanofiltration. Commercial nanofiltration membranes NF-270 Dow Filmtec and NF-DK GE Infrastructure Water&Process Technologies were applied. NF was carried out for mixed water from both water intakes (1 and 2), recovery of 50%, at transmembrane pressure of 0.8-1.2 MPa in the dead-end fi ltration mode. In addition, the permeate obtained in NF was filtered through a column fi lled with 1.0-3.0 mm limestone rock, in order to improve the composition of mineral water. The tested mineral water is the sulphate-chloride-sodium-calcium-magnesium in nature and contains 991 mg/L of SO42- and 2398 mg/L of TDS, while the permeate after NF showed the chloride - sodium hydrogeochemical type (TDS: 780-1470 mg/L, sulfate 10-202.7 mg/L, calcium 23-39.7 mg/L, magnesium 11-28 mg/L). As a result of water treatment in the NF process, high reduction of SO42- ions was obtained (79-98.7%), while the TDS was reduced in 51-64%. Because the process of NF allows for relatively high reduction of bivalent ions, a significant reduction in calcium ion content (84-88%) and magnesium (84-89%) has been also obtained. Monovalent ions were reduced to a lesser extent, i.e. sodium in 46% and bicarbonates in 39-64.1%. Despite obtaining the positive effect of the sulphate ions content reduction, the NF process significantly changed the mineralogy composition of water. The permeate filtration (DK-NF membrane) on the CaCO3 deposit led to a correction of the hydrogeochemical type of water from chloridesodium to chloride-bicarbonate-sodium. The concentration of calcium ions was increased by 60.5% and was 28.2 mg/L, and bicarbonate ions by 7.78% (increased to 195 mg/L). Based on a morphological assessment of the deposits in the SEM image and their chemical composition, the presence of gypsum crystals was detected on the surface of the NF-270 membrane. The deposits formed on the NF-DK membrane were of a completely different character as aggregations of iron and aluminium oxides/hydroxides were found. Such significant mineralogical differences between the secondary deposits crystallising on the surface of the membranes point to the impact of several factors, including membrane characteristics, concentration polarisation, mass transport mechanisms, etc.

中文翻译：

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矿泉水纳滤改造

摘要 人们常常需要通过降低硫酸根离子含量来改善矿泉水的口感。发现对于这种效果，可以使用纳滤（NF）工艺。在这种情况下，假设建议的配方通过以下过程获得 H2S 和 SO42 含量减少的矿泉水：汽提 - UF/MF 或快速过滤 - 纳滤 - 与原水混合或通过钙床过滤。该论文展示了使用矿泉水和纳滤的测试结果。应用了商用纳滤膜 NF-270 Dow Filmtec 和 NF-DK GE Infrastructure Water&Process Technologies。对来自两个进水口（1 和 2）的混合水进行 NF，回收率为 50%，在死端过滤模式下的跨膜压力为 0.8-1.2 MPa。此外，在 NF 中获得的渗透液通过填充有 1.0-3.0 毫米石灰岩的柱子过滤，以改善矿泉水的成分。被测矿泉水为自然界中硫酸盐-氯化物-钠-钙-镁盐类，SO42-991mg/L，TDS 2398mg/L，NF后渗透水为氯化物-钠水化型（TDS：780 -1470 毫克/升，硫酸盐 10-202.7 毫克/升，钙 23-39.7 毫克/升，镁 11-28 毫克/升）。由于NF过程中的水处理，SO42-离子的减少率很高（79-98.7%），而TDS减少了51-64%。由于 NF 过程允许相对较高的二价离子还原，因此还获得了钙离子含量 (84-88%) 和镁 (84-89%) 的显着降低。一价离子减少到较小程度，即 钠为 46%，碳酸氢盐为 39-64.1%。尽管获得了硫酸根离子含量降低的积极效果，但 NF 工艺显着改变了水的矿物组成。CaCO3 沉积物上的渗透过滤（DK-NF 膜）导致将水的水文地球化学类型从氯化钠修正为氯化物-碳酸氢钠-钠。钙离子浓度增加60.5%为28.2mg/L，碳酸氢根离子浓度增加7.78%（增加至195mg/L）。基于对 SEM 图像中沉积物的形态评估及其化学成分，在 NF-270 膜的表面检测到石膏晶体的存在。在 NF-DK 膜上形成的沉积物具有完全不同的特征，因为发现了铁和铝的氧化物/氢氧化物的聚集体。