Four factors are important, first is filtering pressure, second is PH value of water quality, third is the product selection, last is stirring velocity of polyacrylamide.
1, The effect of filter pressure on specific resistance of sludge: generally, with the increase of filtration pressure and filtering speed, the specific resistance of sludge specific resistance is proportional to the filtration pressure by testing and calculation method. With the increase of filtration pressure, sludge specific resistance continues to increase, while filtering speed up, but due to the large pressure, filter medium is easy to be blocking, filtration rate cannot be increased much faster. Therefore, in practice, Works chemical suggests that choose the appropriate filter through the experiment of filter machine according to the different situation.
2, The influence of stirring speed on sludge specific resistance: PAM flocculation is a complicated process of chemical dynamics, stirring rate has a larger effect on flocculation effect. If it hasn't stirred fully, polyacrylamide flocculants and sludge cannot be mixed completely, thus affecting flocculation effect. If stirring is too strong, and breaking has been formed of flocs, also against the flocculation process. Works chemical field experiment 1/20 when mixing rate of 100 s - s - 1 s ~ 200 s - 1/35-1, sludge than resistance is small, while with the increase of stirring speed and a slight increase, but growth is not very obvious. And when the stirring speed, smaller 50 s - s - 1 1/15, is higher than the resistance, sludge dewatering performance degradation, show low stirring speed also against flocculation. Should say so in practice, through the experiment to determine the best mixing condition, and as soon as possible after chemical control of sludge dehydration processing.
3, The influence of pH value on sludge specific resistance: if the change of solution pH will affect the degree of ionization of sludge colloid particles and flocculating agent, thus affecting the molecular chain stretching degree, the solubility and the combination of genes, therefore it has obvious effect on flocculation of the pH value of the system. PH within 6-8, sludge of resistance than the smallest resistance value, dehydration performance is the best. Works chemical in the customer's field experiment measured the pH of concentrated sludge at around 7, so during dehydration, don't need a dosing coagulant aid to adjust pH value, can be directly dehydration processing, after take off the mud, sludge moisture content is low.
4, product selection for the effect of sludge specific resistance: Polyacrylamide anionic, cationic, nonionic, zwitterionic polyacrylamide. The molecular weight of anionic polyacrylamide from 800-20 million, cationic polyacrylamide molecular weight between 800-13 million, ion degrees from 10-80%, nonionic polyacrylamide, zwitterionic polyacrylamide. How to choose from more than 40 varieties suitable polyacrylamide is really a problem. Works chemicals experiment concluded that the use of effect of cationic polyacrylamide is relatively high, high cost performance.