Precautions when using flocculants

In today's widely used flocculants, the role played is also crucial, in the process of using flocculants, how to correctly and reasonably use flocculants, so that it can achieve the best treatment effect, is in the process of using flocculants must be noted. There are many factors affecting the effect of flocculant use.

1, water temperature: under normal circumstances, the water temperature is the best at 20-30 ° C, and the hydrolysis rate of the flocculant will be doubled for every 10 ° C increase in temperature. In particular, aluminum salt is more sensitive to temperature changes, when the temperature is lower than 15℃, the hydrolysis rate of aluminum salt decreases, and the flocculation is loose and not easy to settle, which affects the flocculation effect.

2, pH value: When aluminum salt or iron salt is used as a flocculant, the main flocculation is the electrical neutralization and adsorption bridging of polynuclear polyhydroxyl positive ions, followed by the winding and net trapping of hydroxide precipitation. The optimum pH value of the solution is 6.4~7.8. Fe(OH)3 floc can be formed rapidly when the pH value of ferric salt flocculation is in the range of 5~7, and the best pH value is 6.0~6.4. However, some data indicate that the pH value of 9~11 is better.

3, the type and dosage of flocculant: when choosing the right type of flocculant, we want to take into account the source of the agent, price and cost.

In addition, in the process of use, the flocculant should not bring harmful substances. In the choice of dosage, it is necessary to take into account that when colleagues use a variety of flocculants in combination with the use of flocculants, the type and dosage of flocculants will not conflict, and the factors determined by the dosage are the pH value of the water body, the concentration of the colloid, the electrical positive and negative, the number and so on.

4, stirring intensity and time: the flocculation process includes three stages of mixing, reaction and separation. The basic requirement of the mixing stage is to make the agent quickly and evenly spread into the wastewater and form a micro-flocculation, so the mixing intensity is large, but the time is short. In the reaction stage, the water flow is required to have an appropriate velocity gradient, which not only creates a good collision opportunity for the growth of micro-flocculation, but also prevents the formed flocs from being broken, so the stirring intensity is smaller than the mixing stage, but the time is longer.

5, other factors: it is also necessary to take into account the difference in water samples, adding coagulants when necessary.