The Experiment Research Of Using Alternating Current Variable Frequency To Reinforce Coagulation Treatment Of Low Temperature Andturbidity Water

The low temperature and turbidity water is always a problem in water treatment. Meanwhile, the magnetic theory attracts more and more attention in water treatment technology, the polymeric ferric sulfate (PFS) which is a ferromagnetic gets a wide range of application in water treatment. Therefore, the experiment research is using self-developed AC variable frequency electromagnetic induction device to magnetize PFS solution, and then to reinforce coagulation treatment of low temperature and turbidity water.Through the analysis of the AC variable frequency electromagnetic field intensity influence factors，subsequently, it infers the formula for magnetic field intensity and builds an AC variable frequency magnetic coagulation unit. Treat the low temperature and turbidity water from somewhere as an example, PFS as a strengthening coagulants. By the principle of single factor orthogonal experiment, analyzing the influence of each magnetizing unit parameters to the turbidity of PFS coagulation magnetization water, CODCr, the rest of iron content, the settleability, moisture content, specific resistance of settling sludge.Compared with normal PFS solution, the magnetized PFS solution has more advantages in dealing with low temperature and turbidity water. The pharmaceutical dosage decreased from100mg/L to60mg/L, the water outlet turbidity reduces77%which is from2.70NTU to0.50NTU, CODCr drops33%which is range from24mg/L to16.2mg/L. The optimum condition for magnetization treatment are that magnetic field intensity is2.652mT (indicators for turbidity) and3.536mT (indicators for CODCr), the frequency of magnetic field is90Hz, magnetizing time is3min, cast dosage is60mg/L. The order of each factors which can influence the turbidity of strengthened PFS coagulation water is that cast dosage> magnetic field strength> magnetic field frequency> magnetizing time. The order of each factors which can influence water CODCr is that cast dosage> magnetic field strength> magnetizing time> magnetic field frequency. The content of the rest iron in outlet water indicates the effective utilization rate of PFS to some extent. As the experiment results, the content of rest iron in PFS coagulation outlet water which has been strengthened by alternating electromagnetic field shrinks from0.22mg/L to0.12mg/L which decreased45%, the dangerous of high iron content is reduced obviously. The optimum magnetizes parameters are that magnetic field power is2.652mT, frequency is90Hz, magnetizing time is3min, cast dosage is60%. The order of these factors is that magnetizing time> magnetic field strength> cast dosage> frequency.The settleability has more advantages when using magnetized PFS solution to coagulate floe, the PFS solution can enter the density changing and compaction district, the moisture content decreased from69.2%to65.9%, the specific resistance of sludge reduced from5.35×108s2/g to4.77×108s2/g which drops11%. By the result of the fractal dimension analysis and scanning electron microscopy (SEM) analysis, it comes out obviously that the magnetization coagulation effect and each floes combination degree are better, the lesser internal space, compact structure, the lower floes combination degree which formed from un-magnetized process, more inter space, the structure is relatively loose, formed a unified conclusion with the above experiment results, it indicates that the experiment results are correct. Based on the single factor orthogonal experiment, it comes out the optimum magnetization parameters which with index of the floe settleability, the magnetic field intensity is3.536mT, the magnetic field frequency is80Hz, the magnetizing time is4min, the cast dosage is60mg/L, additionally, the order of these factors is that magnetic field frequency> magnetic field strength> magnetizing time> cast dosage.