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以实际回用水为研究对象,采用4个CDC反应器串联模拟回用水铸铁输水管道,在系统连续运行505 d后,采用SEM、EDS、XRD分析了管道内腐蚀产物的沿程变化特征。此外,在对连续运行期间各反应器中不同形态铁及正磷酸盐磷的浓度进行测定的基础上,研究了腐蚀引起的铁、磷沿程变化。结果表明:模拟回用水铸铁输水管道的腐蚀产物由疏松多孔结构向致密硬壳结构转变;其所含矿物类型主要为γ-Fe2O3、α-Fe OOH和Fe CO3等化合物;腐蚀产物主要含Fe、O、P、Ca、Al等元素,其中Fe、O含量沿程增加,意味着腐蚀产物中铁、氧化物的含量沿程增加。水质测定结果发现,回用水在系统中流经120 min后,水中总铁浓度为进水的23.74倍,其中溶解态铁的贡献不大,增加的主要是铁沉淀物。与此同时,PO3-4-P平均浓度与进水相比降低了18.4%,这与对腐蚀产物的元素分析结果相一致。
Taking the actual reuse water as the research object, four CDC reactors were used to simulate the water cast pipes in series. After the continuous operation of the system for 505 days, the variation characteristics of the corrosion products along the pipeline were analyzed by SEM, EDS and XRD. In addition, on the basis of the determination of the concentration of different forms of iron and orthophosphate in each reactor during continuous operation, the changes of iron and phosphorus due to corrosion were studied. The results show that the corrosion products of the cast-iron water delivery pipelines are changed from loose porous structure to dense hard shell structure. The main mineral types are γ-Fe2O3, α-FeOOH and Fe-CO3. The corrosion products mainly contain Fe , O, P, Ca, Al and other elements, including Fe, O content increases along the way, which means that the corrosion products of iron, oxide content increases along the way. The results of water quality measurement showed that the total iron concentration in water was 23.74 times of the influent after 120 minutes of reusing water flowed through the system, of which the contribution of dissolved iron was small, and the increase was mainly iron precipitate. At the same time, the average concentration of PO3-4-P was reduced by 18.4% compared to the influent water, consistent with the elemental analysis of the corrosion products.