低浊原水导致铝超标的水厂技术控制措施

Technical Control Measures for Aluminum Overproof Caused by Raw Water Low Turbidity in WTP

受地理环境影响,深圳东部地区水库原水呈低浊特征,常规投加聚合氯化铝(PAC)后因缺少聚核,絮凝沉降效果不佳,易导致仅有常规工艺的水厂出水浑浊度及余铝超标,造成供水安全潜在风险。针对上述问题,深圳A水厂采用优化排泥水回收比例、辅助投加石灰、适度提高排泥频次等措施,有效改善了混凝效果,提升了出水水质。长期实践结果表明,在原水平均浑浊度为1.57 NTU,通过回收排泥水将原水浑浊度提高至10 NTU左右,并联合投加5.0~6.0 mg/L PAC和3.0 mg/L石灰时,可使出厂水和管网末梢铝浓度分别降低48.9%和43.1%;浑浊度分别降低10.7%和85.4%,其他各项水质指标均满足《生活饮用水卫生标准》(GB 5749—2006)要求。上述结果表明,A水厂采取的一系列措施切实可行,可有效解决出厂水水质中余铝及浑浊度偏高问题,避免出水水质铝超标风险,可为存在同类问题的水厂提供技术借鉴。

Due to the influence of geographical environment,the raw water of reservoirs in the eastern part of Shenzhen is characterized by low turbidity.Due to the lack of polyaluminum chloride(PAC)after conventional addition,flocculation and sedimentation effect is not good,which can easily lead to excess turbidity and residual aluminum in the effluent of water plants with conventional process only,resulting in potential risk of water supply safety.In view of the above problems,Shenzhen A Water Plant adopted measures such as optimizing the recovery ratio of drainage water,supplementing lime,and moderately increasing drainage frequency,which effectively improved coagulation effect and effluent water quality.Long-term practice results showed that when the average turbidity of raw water was 1.57 NTU,the turbidity of raw water was increased to about 10 NTU by recycling drainage water,and aluminum concentration in factory water and the end of pipe network could be reduced by 48.9%and 43.1%respectively by adding 5.0~6.0 mg/L PAC and 3.0mg/L lime.Turbidity was reduced by 10.7%and 85.4%,respectively.Other water quality indices met the requirements of Standards for Drinking Water Quality(GB 5749—2006).Above results show that a series of measures taken by A Water Plant are practical and feasible,which can effectively solve the problems of residual aluminum and high turbidity in the water quality of the factory and avoid the risk of excessive aluminum in the water quality of effluent.It can provide technical reference for water plants with similar problems.