预加碱强化混凝应急处理模拟突发性铅污染研究

Pre-alkaline enhanced coagulation treatment of the simulated lead-polluted raw water

采用烧杯混凝试验研究了加碱种类、pH值、混凝剂聚氯化铝(PAC)投加量、助凝剂聚丙烯酰胺(PAM)投加量以及初始铅质量浓度对除铅效果的影响。进行了为期1个月规模为4m3/h的中试,对小试结果进行了验证,考察了优化后的应急处理方法对不同铅质量浓度原水的去除效果。小试结果表明,采用石灰乳调pH值的除铅效率优于氢氧化钠和石灰水,最佳pH值为9～10。强化混凝能提高铅的去除效率,PAC最佳投加量为20mg/L,PAM的最佳投加量为0.4mg/L,铅初始质量浓度在2mg/L以下时铅去除率都在97%以上。中试运行结果与小试基本一致。原水铅质量浓度超标168倍以下,采用预加碱强化混凝的应急处理工艺能使滤后水中铅稳定达标,沉淀出水中铅质量浓度低于0.03mg/L。预加碱强化混凝应急技术可行性高,处理费用仅0.02637元/t,为可能突发的水源铅污染事故应急处理提供了技术支持。

The present paper is to introduce our study of the influence of alkali kinds, pH volume, coagulant （PAC） dosage, flocculant （PAM） dosage and the initial lead concentrations on the removing power of lead by pre-alkaline enhanced coagulation treatment. For the above said research purpose, we have conducted the pilot study （4 m^3/h） （which lasted nearly a month）, in hoping to verify the jar results and the removing effect of the various alkali kinds on the sudden lead-polluted water. The jar results show that the removal efficiency of lead-pretreated by lime milk tends to be higher than by sodium hydroxide and limewater. Moreover, the results of our experiments indicate that the removing efficiency of lead is highly influenced by pH value, while the optimum pH value is 9 - 10. Another result is that the removal efficiency can be improved by enhanced coagulation. The optimum dosage of PAC and PAM is 20 mg/L and 0.4 mg/L, respectively. Besides, when the initial concentration is below 2 mg/L, the removal efficiency of lead can be expected to reach 97%. In addition, the pilot testing results prove to be consistent with the jar results. Furthermore, the results also indicate that the emergency treatment helps to lower the lead concentrations in purified water to the standard value steadily when the initial lead concentration is below 168 times of standard value. What is more, the emergency treating technology proves to be of great practicability. The treatment cost is 0.026 37 yuan RMB per ton water. Thus, it can provide a strong technical support for emergency treatment with lead-polluted accident.