Use of polyacrylamide
1, the properties of polyacrylamide flocculant:
Polyacrylamide flocculant is not easy to dissolve in the water, need help to achieve good dissolving effect, the effect of the external force should include two aspects: one is through the water pressure, this mainly depends on how the effect of the scattered head device, whether can bring the equipment to promote a small amount of powder flocculating agent into the more high pressure water; 2 it is by confecting jar stirring, generally high polymer flocculant is chain structure, when the dissolved water solution, the molecular chain, through the bridge or charge neutralization flocculation effect, the length of the chain determines its use effect, so the way of mixing, stirring intensity and stirring time setting is particularly important.
2, polyacrylamide configuration common problems:
A, the equipment has no heating system, and the flocculant will block the pipeline and the dispersant head after being damp;
B, the effect of dispersing head is not good, and the cleaning cycle is short;
C, the screw pump is not used for transportation, which is easy to break the molecular chain of flocculant;
D. The intensity and time of stirring Settings are inappropriate;
E. The setting mode of stirring slurry blade is not reasonable, and the solution in the tank cannot be fully mixed.
3, polyacrylamide flocculant solution often appear problems:
A, unable to provide a high concentration of solution;
B, solution agglomerate;
C) fisheye phenomenon in solution. These problems often affect the effect of the use of flocculant, naturally also affect the use of flocculant. Polyacrylamide (PAM) and its derivatives with a large number of amide groups or other charged groups on the molecular chain, has good water solubility, strong flocculation and adsorption, in the water treatment industry as a flocculant, coagulant aid has been widely used in the application of water, industrial wastewater treatment and sludge dehydration.
4, polyacrylamide use method:
(Can polyacrylamide flocculant be added directly to the treatment system?)
1, polyacrylamide flocculant can not be directly added to the treatment system. It must be dissolved in water before use, and its aqueous solution is used to treat sewage.
2, dissolved polyacrylamide flocculant polymer water should be clean water (such as tap water), not sewage. Normal temperature water can, generally do not need to add temperature. When the water temperature is lower than 5℃, the dissolution rate is very slow, but when the water temperature increases, the dissolution rate is accelerated, but above 40℃, the polymer will accelerate the degradation, affecting the use effect. Generally tap water is suitable for preparing polymer solutions. Water with strong acid, alkali and high salt content is not suitable for preparation.
3, polyacrylamide flocculant polymer solution concentration selection, the general recommendation is 0.1% to 0.3%, that is, 1 liter of water add 1 to 3 grams of polymer powder. The concentration selection should consider the following factors: small mixing tank and large daily dosage, it is recommended to mix slightly thicker (such as 0.3%); When the polymer molecular weight is very high, it is recommended to mix a little dilute (such as 0.1%); When polymer solution is thrown into sewage, if the dispersion condition is not good due to equipment reasons, it is recommended to be slightly diluted. In short, too large polymer concentration will cause too large load of stirrer motor, and will also cause poor dispersion after entering the processing system, affecting the use effect. A thinner polymer concentration will help improve the use effect.
4, polyacrylamide flocculant prepared solution should not be transferred by centrifugal pump, so as not to cause shear degradation of polymer caused by high-speed rotating blades. The specific method of preparation is as follows: add a certain amount of water into the container (such as the beaker in the laboratory, and the matching tank in the factory), calculate the amount of polymer required by the amount of water and concentration, and weigh the polymer; Turn on the electric stirrer and stir the water out of the whirlpool. The linear speed at the end of the stirrer blade should not exceed 8 m/s to avoid polymer degradation. But not too slowly, lest the polymer particles float to the surface, or sink and clump in the water. Slowly spread the polymer into the whirlpool of water, pay attention to the polymer particles into the water can not adhere to each other, clumping. The polymer particles are then stirred for a further period of time to fully dissolve and become a uniform, transparent and viscous solution with no visible clumps.
The stirring time is determined by the following method:
(1). In summer, when the water temperature is higher, negative and cationic polymer need to stir for about 1 hour, non-ionic polymer need to stir for about 2 hours;
(2). When the water temperature is low in winter, the negative and cationic polymers need to be stirred for about 1.5 hours, and the non-ionic polymers need to be stirred for about 3 hours; Also, the higher the concentration, the faster the polymer dissolves. Uneven or inadequate dissolution will affect the effect of use. How to store: polyacrylamide in a dry, cool place can be stored for more than two years, but with the solution, its storage time is very limited. Generally speaking, when the solution concentration is 0.1%, the non-anionic polymer solution does not exceed one week; Cationic polymer solution does not exceed one day. The stability of a solution depends on the concentration, and the thicker the solution (e.g., 3% to 5%), the longer it will last. However, 3 to 5 percent solution can not be directly treated with sewage, and must be diluted before use. Cationic polyacrylamide solution is stable at pH < 5.5, but rapidly fails due to hydrolysis at pH > 6. It is more sensitive to iron and calcium and magnesium ions than anionic polymers. Iron ion is the catalyst that causes the chemical degradation of all polyacrylamide, therefore, when preparing, transferring and storing polyacrylamide solution, iron ion should be avoided as far as possible. The equipment in contact with the solution is made of stainless steel, plastic, fiberglass or resin coated carbon steel.