交变电磁场在混凝技术中的运用

Application of alternative electromagnetic field in coagulation technology

电磁场变化对聚合硫酸铁(PFS)的混凝性能有明显影响。利用自制的交流变频电磁感应磁化装置对PFS溶液进行磁化处理,以Zeta电位为指标,分析对比了磁化前后PFS的稳定性以及磁化效应的消滞时间;以黄河水为试验水样,以交变电磁场的电压、电流、频率、磁化时间及投药量为影响因素,进行了单因素及优化工艺研究。结果表明,PFS溶液静置0.5 h后进行混凝试验效果较好,磁化后PFS的稳定性提高27%,磁化效应能保持2.5 h。电磁场能明显增强聚合硫酸铁的混凝效果,PFS磁化混凝的最佳反应条件为:2%的PFS溶液投药量4 mL,电压100 V,频率150 Hz,电流0.7 A,磁化时间60 s。与常规处理相比,此条件下进行混凝试验的出水浊度由3.26 NTU降至0.27 NTU,COD由38 mg/L降至21 mg/L,且最佳投药量由7 mL降至4 mL。各因素影响混凝出水效果的主次关系为加药量、频率、电压、电流、磁化时间。

The paper is to present our renovation in the application of alternative electromagnetic field in coagulation technology polymeric ferric sulfate （PFS）. The previous studies on the relation of PFS and the electromagnetic field, so far as we know, reveal that the electromagnetic field tends to have strong effect on the coagulation properties of PFS. Therefore, we have managed to conduct a bench test on the cooperation of PFS and electromagnetic field at room temperature in this paper by magnetizing the PFS solution for experiments with a self-developed electromagnetic device with AC frequency conversion. In our experiments, we have compared the stability gap between the magnetized and non-magnetized PFS, and confirmed the duration of magnetizing effect. While taking our water sample from the Yellow River as the test subject, we have studied the effects of alternating electromagnetic field on PFS via the single factor and orthogonal coagulation experiments. Thus,we have found that the zeta potential was closely related to the coagulation performance. When the PFS solution stood at 0.5 h, the positive coagulation effects of PFS could be observed. And, in this moment, the stability of magnetized PFS can be found improved by 27%, with the magnetizing effect kept in 2.5 h. The highest levels were found as follows： dosage of 2% to the PFS solution 4 mL, voltage 100 V, frequency 150 Hz, current 0.7 A, with the magnetizing time lasting 60 seconds. Comparing our method with the conventional approaches, the advantages of our method lie in that： water turbidity can be reduced from 3.26 NTU to 0.27 NTU, reduction of COD from 38 mg/L to 21 mg/L, the magnetized PFS can be saved to 4 mL under the optimal conditions mentioned above. The effects of the above said factors on the water samples can be found in the following order of dosage〉frequency〉voltage〉current〉magnetization time. All the above mentioned results indicate that the cooperation of PFS and electromagnetic field we have renovated proves to have a great advantage of effluent quality, energy-saving function with no secondary pollutants, thus enhancing the availability of our renovation for practical application and popularization.