CO_(2)-石灰联用技术在水厂低硬度原水处理中的应用及成效

Application and Performance of Combined Process of CO_(2)-Lime for Low-Hardness Raw Water Treatment in WTP

受地理位置影响,珠江下游低硬度、低碱度原水对给水厂出水水质及管网稳定带来显著影响,对供水安全带来潜在风险。针对这一问题,深圳某水厂基于低硬度水再矿化理论基础,总结再矿化工程实践经验,建立低硬度水再矿化评价标准,制定CO_(2)-石灰联用技术再矿化工程改造措施,并通过优化再矿化试剂投加量,取得较为显著的效果。该实践成效主要表现为:在原水水质硬度较低、化学稳定性较差条件下(总碱度<18.5 mg/L CaCO_(3),CCPP约为-28.29),CO_(2)-石灰联合投加后,出厂水pH值由原来的7.14提高至7.68,碱度由15 mg/L提高至75 mg/L,钙离子由31 mg/L提高至87 mg/L,管网沿线取样点水质pH值平均提升0.2,总铁含量显著下降,由原来的0.02~0.72 mg/L稳定在0.20 mg/L左右,管网水质明显改善。同时,管网水的化学稳定性显著改善,LSI和CCPP分别提升至0.5~1.0和2~12,由原来的严重腐蚀倾向转化为结垢倾向。

Affecting by geographic position,the low-hardness and low-alkalinity of raw water in the downstream of Pearl River has a significant impact on effluent quality and pipe network stability,and then causing potential risks in water supply safety.For this problem,a water supply plant in Shenzhen basing on the theory of mineralization of low-hardness water,summarized the experience of mineralization engineering,formulated low hardness water mineralization standard and CO_(2)-line combined strategy remineralization project tansformation measures,as well as optimized the dosage of remineralization reagent,achieving a good result of water mineralization.Results show that under the condition of the raw water being low-hardness and low-alkalinity(total alkalinity<18.5 mg/L CaCO_(3),CCPP≈-28.29),effluent quality is obviously improved after dosing the CO_(2) combined lime.Effluent pH value increased from 7.14 to 7.68 and alkalinity increased from 15 mg/L to 75 mg/L,as well as the concentration of Ca^(2+)increased from 31 mg/L to 87 mg/L.Besides,pipe water quality is also improved significantly.Averaged pH value along the pipe increased 0.2,and the concentration of total Fe decreased from 0.02~0.72 mg/L to averaged 0.20 mg/L.Due to improved chemical stability in pipe water,LSI and CCPP are increased to 0.5~1.0 and 2~12,respectively,resulting in the tendency of severe corrosion converting into the scaling.