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淡化海水由于氯离子浓度高、碱度低而具有侵蚀性,在进入供水管网前一般需进行矿化来提高硬度和碱度;使用有内衬的管网输送也可以进一步减轻其侵蚀危害。利用水泥砂浆内衬管搭建管段模拟反应器,测试了不同条件下淡化海水在其中长时间输送时的水质变化。结果表明,对于未矿化和矿化后的淡化海水,运行前5 d管段反应器内水的pH值、总碱度、溶解性SiO_2均显著升高,之后下降,后15 d基本平衡。未矿化水在管段反应器停留时,其钙离子浓度(以CaCO_3计)在初期从1 mg/L急剧升高到50 mg/L,矿化水则从50 mg/L降低到10 mg/L左右,后期都达到基本相同的平衡浓度;镁离子浓度基本保持不变,在1~5 mg/L之间。矿化水加氯组和不加氯组的TOC均是初期较高,而后呈下降趋势,加氯组的TOC浓度高于不加氯组。两组均出现铝严重超标现象,铁浓度维持在0.3 mg/L上下,铬仅在初期超标。因此,建议使用水泥砂浆内衬管输送淡化海水之前,需要通水冲洗4~5 d以使水质达到稳定。
Desalinated seawater, which is aggressive due to its high concentration of chloride ions and low alkalinity, generally requires mineralization to increase hardness and alkalinity before it enters the water distribution network; the use of lined pipelines can further mitigate the erosion hazard. The cement mortar liner tube was used to build a tube reactor to test the water quality of desalinated seawater under long-term transport under different conditions. The results showed that for unsalted and mineralized desalinated sea water, the pH value, total alkalinity and dissolved SiO 2 in the reactor before 5 days of operation were significantly increased, then decreased, and basically balanced after 15 days. When the non-mineralized water stayed in the pipe reactor, its calcium concentration (calculated as CaCO 3) rapidly increased from 1 mg / L to 50 mg / L in the initial stage and the mineralized water decreased from 50 mg / L to 10 mg / L, and later reached the same equilibrium concentration; the concentration of magnesium remained unchanged at 1 ~ 5 mg / L. The TOC values of mineralized water chlorination and non-chlorination groups were higher initially and then decreased, and the TOC concentration of chlorination group was higher than that of non-chlorination group. Both of the two groups experienced serious aluminum excesses, the iron concentration was maintained at 0.3 mg / L, and chromium exceeded the initial level only. Therefore, it is recommended to use cement mortar liner to deliver desalinated seawater before flushing for 4-5 d to stabilize the water quality.