The so-called magnetic coagulation and sedimentation technology is to add magnetic powder simultaneously to the ordinary coagulation and sedimentation process to integrate it with the flocculation of pollutants to enhance the effect of coagulation and flocculation, making the generated flocs denser and stronger, thereby achieving the purpose of high-speed sedimentation. Magnetic powder can be recycled through magnetic drum recycling.
Mechanism of magnetic coagulation
According to the coagulation mechanism, adding coagulant mainly changes the surface properties of colloids or suspended particles so that the attraction energy of colloids or flocs is greater than the repulsive energy and promotes coagulation. The main function of adding flocculants is to increase particle aggregation through bridging.
The formation process of magnetic flocs is the same as that of non-magnetic flocs, and is completed under the action of coagulant. The test results of the ζ potential of magnetic powder show that the surface of the magnetic powder is electronegative (ζ=-10.5 mV). It can be inferred that the formation experience of magnetic flocs is as follows: first, the positive ions generated by the hydrolysis of the coagulant gather around the negatively charged colloidal particles and magnetic powder particles due to adsorption and electroneutralization; then, due to the disappearance of the electrostatic repulsion, the colloid particles and the magnetic powder particles and between themselves grow up through van der Waals attraction; finally, through the bridging effect of the flocculant, the aggregates are further flocculated into large flocs and precipitated. It can be seen that there is no essential difference between the magnetic flocculation reaction with the participation of magnetic powder and the flocculation reaction without the participation of magnetic powder. Magnetic powder is the same as other fine suspended particles, and the mechanism of coagulant also works on it. The existing coagulation theory also has guiding significance for the magnetic flocculation reaction. All enhanced coagulation measures will promote the magnetic flocculation reaction.
